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- From: gfield@zk3.dec.com (Gary Field)
- Newsgroups: comp.periphs.scsi,comp.answers,news.answers
- Subject: comp.periphs.scsi FAQ part 1 of 2
- Followup-To: comp.periphs.scsi
- Organization: Digital Equipment Corp.
- Lines: 4345
- Approved: news-answers-request@MIT.EDU
- Distribution: world
- Expires: 5 May 1998 05:00:03 GMT
- Message-ID: <GFIELD.98Apr1125329@scuzzy.zk3.dec.com>
- Reply-To: gfield@zk3.dec.com (Gary Field)
- Summary: This posting contains a list of Frequently Asked
- Questions (and their answers) about SCSI. It
- should be read by anyone who wishes to post to the
- comp.periphs.scsi newsgroup.
- Date: Tue, 05 May 1998 11:34:11 GMT
- NNTP-Posting-Host: red.gdansk.sprint.pl
- NNTP-Posting-Date: Tue, 05 May 1998 13:34:11 MET DST
- Xref: senator-bedfellow.mit.edu comp.periphs.scsi:112214 comp.answers:31192 news.answers:129372
-
- Archive-name: scsi-faq/part1
- Posting-Frequency: monthly
- Last-modified: 1998/3/31
-
- Note:
- The FAQ has undergone a facelift. The source file is now a Microsoft Word
- for Windows (Office '97) document so that it is be possible to
- generate both a text and an HTML version from the same document.
- I'm not thrilled with the text file that I'm getting out of Microsoft Word,
- but I believe all the information is there.
- The HTML version will make it much easier and faster to look up information
- by providing hyperlinks. The text version will continue to be produced
- until there is no significant interest in it. If you would be unable to
- read an HTML version of the FAQ and want to make sure I continue to
- produce the plain text version, email me at: gfield@zk3.dec.com
- explaining why. So far I have only received one request for the text
- version, so it may not live much longer.
-
- Gary Field
- -----------------------------------------------------------------------
-
-
- SCSI FAQ
- Frequently Asked Questions List for comp.periphs.scsi
- Current Editor: Gary Field (gfield@zk3.dec.com)
- (Where you see reference to [Editor(GF)] that means me.)
- Last updated: March 31, 1998
-
- Skip to Table of Contents
-
- FAQ history: Created by Johnathan Vail (vail@prepress.pps.com) from
- articles submitted to him by comp.periph.scsi readers.
- Maintained by Johnathan Vail until November 1993.
-
- Where to get the latest copy of this FAQ:
- The comp.periphs.scsi FAQ is posted to Usenet during the first week
- of each month. As of February 1998 it is available in both a text
- file version and an HTML version. Some sites may not yet be archiving
- the HTML version.
- A recent version can be obtained via anonymous ftp from:
- ftp.ultranet.com:
- pub/gfield/scsi/scsifaq.txt and scsifaq.html
- Note: the gfield directory will not show up using DIR, but it's
- actually there. Just CD to it.
- OR
- rtfm.mit.edu:
- pub/usenet-by-group/comp.periphs.scsi/comp.periphs.scsi_FAQ_part_*
- via World Wide Web (WWW):
- http://www.cis.ohio-state.edu/hypertext/faq/usenet/scsi-faq/
- OR
- http://www.ultranet.com/~gfield/gary/scsi.html
- OR
- http://fieldnet.ne.mediaone.net/gary/scsi.html
-
-
- Attention SCSI vendors: There are a few articles in this FAQ where vendor
- contact information, and in a few cases, part numbers, are listed.
- This is not an attempt to steer business to any particular vendor but
- only to provide possible sources of certain "hard to find" SCSI
- accessories (particularly special cables, adapters and terminators).
- If you want to be listed in one or more articles please send your
- contact info and which items you can provide to the FAQ editor.
- I will not include pointers for devices like hard disks, tapes,
- CDROMs etc., which I consider readily available.
-
-
- Table of Contents:
- Categories:
- Generic SCSI Questions
- SCSI Documentation and Books
- SCSI Manufacturer Contact Information
- Manufacturer Specific Questions
- Platform Specific Questions
- Device Model Specific Questions
- Host Adapter Model Specific Questions
-
- Generic SCSI Questions:
- What is SCSI?
- What information should I provide when asking a question in the
- comp.periphs.scsi newsgroup?
- What do all these SCSI buzzwords mean?
- What is the history of SCSI (What is SASI)?
- Can I access a SASI drive with a SCSI controller?
- How should I lay out my SCSI bus? What should I avoid?
- Where do I put the terminators?
- What is a SCSI terminator? Why do I need them?
- Where Should I place the SCSI adapter on the SCSI bus?
- Is the spacing of connectors on a SCSI cable important?
- How long can my SCSI bus be?
- What are the pros and cons regarding SCSI vs IDE/ATA ?
- Should I spend the extra money on SCSI or just get IDE?
- Can I have both IDE/ATA drives and SCSI in the same system?
- Is it possible for two computers to access the same SCSI disks?
- Is it possible for two computers to access the same SCSI tape?
- What is FAST SCSI ?
- How can I check a passive SCSI terminator ?
- Can someone explain to me the difference between 'normal' SCSI and
- differential SCSI?
- What are the pinouts for differential SCSI?
- How can I tell if I have a single ended or differential drive ?
- What are the pinouts for SCSI connectors?
- I've got a SCSI disk with an 80 pin connector. Someone called it an
- SCA drive. Can I connect this to my SCSI bus?
- What is the difference between SCSI-1 and SCSI-2?
- What is the difference between SCSI-2 and SCSI-3?
- Are SCSI-3 hard drives and/or controllers available yet?
- After perusing the latest issue of Computer Shopper, I came away with
- the impression that companies are calling F&W SCSI-2 HD's SCSI-3. Is
- this an incorrect assumption, or is F&W SCSI-2 known as SCSI-3?
- Is SYNCHRONOUS faster than ASYNCHRONOUS?
- Is the NCR 53C90 Faster than spec?
- What is ASPI?
- What is CAM?
- What is FPT (Termination)?
- What is Active Termination?
- Why Is Active Termination Better?
- How can I tell whether an unmarked terminator is active or passive?
- Where can I buy terminators ?
- What is Plug and Play SCSI?
- Will attaching a SCSI-1 device to my SCSI-2 bus hurt its performance?
- Can I connect a SCSI-3 disk to my SCSI-1 host adapter?
- Can I connect a SCSI-2 CDROM to a SCSI-3 host adapter?
- Can I connect a Narrow SCSI2 disk to a WIDE SCSI3 host adapter?
- Can I connect a WIDE device to my narrow SCSI host adapter?
- Can I connect a narrow device to my WIDE SCSI host adapter?
- How does device ID numbering work with WIDE vs NARROW devices?
- What is spindle-sync and why would I want it?
- What if I have a SCSI drive larger than a gigabyte (1024MB)?
- My SCSI bus works, but is not reliable. What should I look at?
- Where can I find information about programming using the ASPI
- interface from DOS and Windows?
- What kinds of Optical Drives are available?
- I connected an old narrow device to my WIDE bus with a 68 pin to 50
- pin adapter. Now my TERMPWR seems to be shorted out. What is
- happening?
-
- Table of Contents
- SCSI Documentation and Books:
- Where can I get various SCSI documentation?
- How can I find out about the emerging SCSI standards?
- Where can I get official ANSI SCSI documents?
- What SCSI books and tutorials are available?
- Where can I find SCSI info on the Web?
- Where can I get information on various disk drives and controllers?
-
- Table of Contents
- SCSI Manufacturer Contact Information:
- How can I contact:
- Adaptec
- Archive Corporation (see Seagate)
- BusLogic /Bustek / Mylex
- Corel
- Future Domain
- Fujitsu
- Quantum
- Seagate
- Conner Peripherals
- Maxtor
- NCR
- Philips
- Symbios Logic
- UltraStor
- Tecmar Technologies (formerly Wangtek, WangDAT, Sytron, and Rexon)
- Western Digital
- DPT (Distributed Processing Technology)
- Micropolis
- Legacy Storage System
- Table of Contents
- Manufacturer Specific Questions:
- Where can I get SCSICNTL.EXE and other Adaptec files?
- Where can I get technical information and jumper settings for HP
- drives ?
- Who manufactures SCSI extenders and Single-Ended to Differential
- converters ?
-
- Table of Contents
- Platform Specific Questions:
- What are the general steps I need to do to install a SCSI disk to be
- used with Windows?
- My SCSI CDROM only works when Windows 95 is installed. How can I get
- Windows 95 installed? Is this a catch 22?
- Are there any storage related reasons to upgrade to Windows 95 OSR2?
- Under Windows 95 OSR2 I can only see the first 8 GB of my 9 GB disk.
- WhatÆs going on?
- I'm having problems with my Adaptec 2940xx under Windows 95 but it
- works OK under other O/Ses (like Linux or Windows NT).
-
- Table of Contents
- Device Model Specific Questions:
- What are the jumpers on my Conner drive?
- What are the jumpers for my Wangtek 5150 drive?
- How do I configure my HP DDS DAT tape drive?
-
- Table of Contents
- Host Adapter Model Specific Questions:
- What is the problem with the Adaptec 1542C and external cables?
- What is the difference between the Adaptec 1542A and 1542B?
- What are the differences between the Adaptec 1542B and the 1542C?
- What are the differences between the 1542C and the 1542CF?
- Where can I get drivers (ASPI and other) for the WD7000 FASST2 host
- adapter?
- How to replace Macintosh internal HD and terminate the SCSI chain
- properly?
- I changed the host adapter in my system and now my disk doesnÆt work.
- Why?
-
- Table of Contents
- End
-
-
- Answers to the Questions:
- ====
- QUESTION: What is SCSI?
- ANSWER From: LSD, L.J.Sak@Kub. Edited by Gary
- Field(gfield@zk3.dec.com)
- ====
-
- SCSI stands for Small Computer Systems Interface. It's a standard for
- connecting peripherals to your computer via a standard hardware
- interface, which uses standard SCSI commands. The SCSI standard can
- be divided into SCSI (SCSI1) and SCSI2 (SCSI wide and SCSI wide and
- fast).
- SCSI2 is the most recent version of the SCSI command specification
- and allows for scanners, hard disk drives, CD-ROM players, tapes [and
- many other devices] to connect.
-
-
- Table of Contents
- ====
- Question: What information should I provide when asking a question in
- the comp.periphs.scsi newsgroup?
- Answer From: Gary Field(gfield@zk3.dec.com)
- ====
- In order for most SCSI problems to be resolved, one needs to provide
- at least the following:
- Type of system (PC, SPARC or Alpha Workstation, etc.)
- If PC, what type of motherboard?
- Operating System (DOS, Windows 3.x, Win 95/98, Win NT 4/5, Linux,
- other UNIX)
- Specific SCSI host adapter (Symbios xxxx, Adaptec xxxx, etc)
- List of attached devices (and for disks, whether they're WIDE or
- NARROW)
- Length of SCSI bus
- Where the terminators are located
- Whether the configuration is new, or was working before.
-
- It may seem like a lot of information to provide, but unless you
- have some SCSI experience, you may not realize how many factors can
- affect whether the system works properly or not.
- If you don't know what some of these things mean, read the rest of
- this document until you do. You'll get much more help if you appear
- to have made an effort to find the answer on your own before asking
- for help.
- Asking a question like "My scanner doesn't work, how come?" may not
- even get you a response.
-
- Table of Contents
- ====
- Question: What do all these SCSI buzzwords mean?
- Answer From: hennes@stack.urc.tue.nl (Hennes Passmann)[Editor(GF)]
- ====
-
- -Host adapter:
- The card that connects your computer to the SCSI-bus.
- Usually called SCSI-controller by marketing droids.
-
- -Terminators (passive):
- A group of resistors on the physical ends of a single ended SCSI-bus
- (and only on these ends) that dampens reflected signals from the ends
- of the bus. Each terminated signal is connected by:
- * 220 Ohm to +5 volt (TERMPWR)
- * 330 Ohm to ground.
- The 18 signals that are terminated are:
- I/O, Req, C/D, Sel, Msg, Rst, Ack, Bsy, Atn, DB(p), DB(7) ... DB(0).
-
- -Terminators (active).
- Rather than passive terminators that use TERMPWR which may not be
- exactly +5v, active terminators use a voltage regulator.
-
- -Single ended:
- "Normal" electrical signals. Uses open collector to the SCSI bus,
- [usually] survives wrong cable insertion. DIFFSENSE signal is used to
- detect connection of wrong type devices.
- The max. length for SCSI-1 is a 6 meter cable with stubs of max 10cm
- allowed to connect a device to the main-cable. Most devices are
- single ended.
-
- -Differential:
- Uses two wires to drive one signal.
- Max. cable length of 25 meters.
- Electrically incompatible with single ended devices!
- SCSI-1 and upwards.
-
- -Apple kludge:
- The single ended 50 pins cable has been reduced to 25 pins by tying
- most grounds together. DB25 connector (like a parallel port). Often
- used as the external SCSI connector.
-
- -Asynchronyous SCSI:
- A way of sending data over the SCSI-bus.
- The initiator sends a command or data over the bus and then waits
- until it receives a reply (e.g. an ACKnowledge). All commands are
- send asynchronously over the 8 bit part of the SCSI-bus.
-
- -Synchronous SCSI.
- Rather then waiting for an ACK, devices that both support synchronous
- SCSI can send multiple bytes over the bus in the folowing way:
- send data1 : send data2 : ... : send data3 (max outstanding bytes)
- : wait : wait : response1 : reponse2: ...
- This improves throughput, especially if you use long cables. (The
- time that a signal travels from one end of the cable to the other end
- of the cable IS relevant.)
-
- -Fast SCSI:
- Fast SCSI allows faster timing on the bus. ( 10MHz instead of 5MHz )
- On a 8 bit SCSI-bus this increases the *theoretical* maximum speed
- from 5MB/s to 10MB/s. I know of no single drive that reaches these
- speeds.
-
- - RAID:[Added by Editor(GF) Corrected by Fredrik Bjork
- (ace@varberg.se)]
- A Redundant Array of Independant Disks is a set of drives connected
- to a special dual ported SCSI adapter that allows certain types of
- access optimization. A RAID 0 array stripes the data accross multiple
- drives to decrease data latency. A RAID 1 array mirrors the data on
- multiple drives for increased data integrity. A RAID 5 array uses
- extra drives in a distributed manner to store parity information that
- can be used to apply data correction and recover any data in the
- event of any individual disk failure. This provides high reliability.
-
- -Ultra SCSI:
- Allows up to 20MHz signals on the bus.
-
- -Wide SCSI:
- Uses an extra cable (or 68 pin P cable) to send the data 16 or 32
- bits wide. This allows for double or quadruple speed over the SCSI-
- bus. Note that no *single* drive reaches these speeds, but groups of
- several drives can.
-
- Table of Contents
- ===
- Question: What is the history of SCSI (What is SASI)?
- Answer From: hennes@stack.urc.tue.nl (Hennes Passmann)
- ====
-
- #include <stddisclaimer.h>
-
-
- 1979 The disk drive manufacturer Shugart begin working on a new drive
- interface with logical rather then physical adressing.
- It used 6 byte commands.
-
- Shugart Associates Systems Interface (20 pages long) made public.
-
- A few SASI drives are developed
-
- 1980 Attempt to make SASI an ANSI standard failed.
-
- 1981 Shugart and NCR request an ANSI committee be formed for SASI
-
- 1982 ANSI committee X3T9.2 is formed.
- SCSI adds the ATN signal to the bus and creates the message protocol.
-
- 1983 Development of SCSI drives and ST-506 to SCSI bridges begins.
-
- 1985 CCS (Common Command Set) used in most disk drives.
- Only disk and tape commands were adequately specified.
-
- 1986 Work begins on SCSI-2.
-
- 1986 SCSI-1 becomes official as ANSI X3.131-1986
- (yes, after the work had begun on SCSI-2)
- 6 and 10 byte commands.
- SCSI-2 specifies CDROM commands.
-
- 1988 Production of SCSI-2 devices begins.
-
-
- 1993 Work begins on SCSI-3.
-
- 1994 SCSI-2 becomes official as X3.131-1994.
-
- SCSI-2 is backwards compatible with SCSI-1 and adds the following:
- *Fast SCSI-2. Optional bus speed of 10MHz instead of 5MHz.
- *Wide Optional 16 or 32 bit cable instead of 8 bits.
- *more commands defined, many optional (I'm not going to type the
- entire list here)
- *broader support for non-disk devices (tape.CDROM,Scanners....)
-
- SCSI-2 devices can talk to the host adaptor on their own inititive.
- (e.g. to set in which mode they shoud operate, FAST or not, wide,
- extra wide or normal ...) This can confuse some older SCSI-1 HA.
-
- 1995 Production of drives that have some SCSI-3 enhancements.
-
- Ultra SCSI: Bus speed of 20MHz?
-
- 1996: SCSI-3 proposals include:
- -Support for graphical commands.
- -Fibre channel protocol (fibre channel)
- -Serial packet protocol (IEEE P1394)
- -SCSI-3 general packet protocol (almost all serial interfaces) and of
- course the old SCSI-2 commands and more.
- -Low Voltage Differential Parallel interface
- -CD-R command set and algorithms
-
- Future(after 1996): SCSI-3 becomes official
- SCSI becomes a more network-like environment where devices can be
- physically distributed and shared more easily.
-
- Table of Contents
- ===
- Question: Can I access SASI drive with SCSI controller?
- Answer From: Gary Field(gfield@zk3.dec.com)
- ====
-
- Well, the answer is a definite maybe, but very unlikely. Old low
- performance SCSI adapters and drivers that use only a minimal subset
- of the SCSI commands may work with SASI devices that happen to
- support the INQUIRY command. Newer adapters and drivers expect to be
- able to use messages and will get very upset with a SASI device that
- doesn't understand them.
- In reality, there is no practical reason to do this. Any SASI device
- is so obsolete that is has no real value in a system being used in
- 1990 or later.
-
- Table of Contents
- ====
- Question: How should I lay out my SCSI bus? What should I avoid?
- Question: Where do I put the terminators?
- Question: Where should the adapter card be placed?
- Answers From: Nick Kralevich <nickkral@cory.eecs.berkeley.edu>
- edited by Gary Field (gfield@zk3.dec.com)
- ====
-
- One confusing thing about SCSI is what the SCSI bus is supposed to
- look
- like, and how devices should be placed on the bus.
-
- The SCSI bus MUST run continuously from one device to another, like
- this:
-
- DEVICE A --------- DEVICE B --------- DEVICE C -------- DEVICE D
-
- Where device A, B, C, and D can either be internal or external
- devices.
-
- The devices on the SCSI bus should have at least 4 to 6 inches of
- cable between devices. This is to satisfy the SCSI-2 requirement that
- "stubs" be placed at least .1 meters apart. Some devices that have a
- lot of internal wiring between the connector and the SCSI chip can
- look like a "stub" or bus discontinuity. The reason for all these
- requirements is that a SCSI bus is really 18 "transmission lines" in
- the wave theory sense. A pulse propagating along it will "reflect"
- from any part of the transmission line that is different from the
- rest of it. These relections add and subtract in odd combinations and
- cause the original pulse to be distorted and corrupted. The
- terminators "absorb" the energy from the pulses and prevent
- relections from the ends of the bus. They do this because they
- (hopefully) have the same impedance as the rest of the transmission
- line.
-
- The SCSI bus must not have any "Y" shape cabling. For example,
- setting up a cable that looks like this is NOT allowed:
-
- DEVICE B
- \
- \
- \
- >------------- DEVICE C ----------- DEVICE D
- /
- /
- /
- DEVICE A
-
-
- Where do I put the terminators?
-
- Termination must be present at two and ONLY two positions on the SCSI
- bus, at the beginning of the SCSI bus, and at the end of the SCSI
- bus. There MUST be no more than two, and no less than two,
- terminators on the bus.
- Termination must occur within 4 inches (.1 meter) of the ends of the
- SCSI bus.
-
- The following ARE acceptable:
- +------------+----------+-----------+-----------+---------+
- | | | | | |
- DEVICE A Unconnected Unconnected DEVICE B DEVICE C Adapter
- Terminated Terminated
-
- +------------+----------+-----------+-----------+---------+
- | | | | | |
- DEVICE A Unconnected DEVICE B Unconnected Adapter DEVICE C
- Terminated Terminated
-
-
- +------------+----------+-----------+-----------+---------+
- | | | | | |
- Adapter DEVICE A DEVICE B Unconnected Unconnected DEVICE C
- Terminated Terminated
-
- The following ARE NOT allowed:
-
- +------------+----------+-----------+-------------------+
- | | | | |
- DEVICE A DEVICE B Adapter Unconnected Unconnected
- Terminated Terminated
-
- +------------+----------+-----------+-----------+
- | | | | |
- Termination DEVICE A DEVICE B DEVICE C Adapter
- Terminated
-
-
- Where Should I place the SCSI adapter on the SCSI bus?
-
- The placement of the SCSI adapter card can be on the end, at the
- beginning, or somewhere in the middle of the SCSI bus.
- Quite frankly, placement of the controller card isn't special.
- The adapter card is just another device on the SCSI bus.
- As long as the rules above and in other sections of this FAQ are
- followed, there should be no problem placing the adapter card
- anywhere on the SCSI bus.
-
- However, if you place the adapter card somewhere in the middle of the
- SCSI bus, you must be sure to disable termination on the adapter
- card. As noted previously, a SCSI device is only allowed to have
- terminations if it's at the end of the bus. Only two terminators are
- allowed to terminate the SCSI bus, one at each end.
- One last note: It doesn't make any difference where each SCSI ID is
- placed along the bus. It only matters that no two devices have the
- same ID. Don't forget that the adapter has an ID too. (Usually ID 7).
-
-
- Table of Contents
- ===
- Question: What is a SCSI terminator? Why do I need them?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- A SCSI bus is a transmission line. To prevent reflections from the
- ends of the bus, you need a device which makes the transmission line
- appear to be of infinite length. This is done by attaching resistors
- which have the same resistance as the characteristic impedance of the
- transmission line to the ends of the bus. Also, since SCSI line
- drivers are open-collector (which can only pull a signal low), a
- pull-up resistor is needed to pull the signal high when it's not
- asserted.
- If the ends of the bus are not terminated, the signal pulses will
- reflect off these open ends and travel back along the bus in the
- other direction. The resulting adding and cancelling of signal
- amplitudes distorts and destroys the SCSI signals.
- There are two basic types of terminators, active and passive.
- Table of Contents
- ===
- Question: Is the spacing of connectors on a SCSI cable important?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- The ANSI SCSI spec's say that "stubs" on a SCSI bus must not be any
- more than .1 meters (4 in.) long. In the most recent spec's there are
- also guidelines that say you shouldn't place "stubs" any closer than
- .3 meters (12 in.) apart. Since each device attached acts as a
- "stub", you really shouldn't place connectors any closer than this.
- This gets to be more important as your bus performance goes up. i.e.
- with Fast20 it is very important, but with SCSI-1 it doesn't really
- matter much. Since Fast20 also limits your overall bus length to 1.5
- meters (for single ended) this also means you shouldn't really
- connect more than 5 devices for best reliability.
-
- Table of Contents
- ===
- QUESTION: How long can my SCSI bus be?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
-
- The SCSI length limits are based on the speed of the fastest device
- attached to the bus.
-
- Here's a table which shows the limits:
-
- Speed of FASTEST device Max. single-ended bus length Max. HV
- Diff. bus len.
- 5 MHz (SCSI1 synch.) 6 meters 25
- meters
- 10 MHz (SCSI2 FAST) 3 meters(not rec.) 25 meters
- 20 MHz (Ultra or Fast20) 1.5 meters(not rec.) ?
- 40 MHz (Ultra2 or Fast40) Only differential connections allowed
- These limits assume the use of good quality cable which maintains its
- characteristic impedance between 90 and 130 Ohms and the use of
- active terminators at each end of the bus.
- Notice that I used the term MHz to specify speed since MB/sec.
- changes with the bus width.
-
- When Low Voltage Differential(LVD) devices are available, this will
- allow lengths between the single-ended numbers and the HV Diff.
- numbers.
-
- Note: Bus width doesn't change the maximum allowable length.
- The bus width is independent of bus length or speed.
-
- The above table assumes that you know the max. speed of your devices
- (usually by looking in the manuals). Some software (like Adaptec EZ-
- SCSI) provides a driver status monitor which will tell you what mode
- the devices are actually in. This is important since any synchronous
- speed must be negotiated by either the device or the adapter. The
- speed actually used will be the least common denominator between the
- two.
- For example, if a Fast20 disk is attached to a 'SCSI2" host adapter
- that only goes up to Fast10, the device will only run at 10 MHz.
-
- Table of Contents
- ====
- QUESTION: What are the pros and cons regarding SCSI vs IDE/ATA ?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Pros of IDE/ATA:
- Inexpensive due to high volume of production
- Supported directly by system BIOS in most cases
- Less overhead per command
-
- Cons of IDE/ATA:
- Very limited device attachment (two drives including CDROMs)
- Only supports disk, CDROM (and limited support for tape)
- Single threaded (commands do not overlap even with a second drive)
- CPU is tied up transferring all data
- IDE/ATA and ATAPI evolved as one kludge on top of another
- (so compatibility is not always good)
- Cannot handle scatter/gather operations well
-
- Pros of SCSI:
- Flexible device attachment (up to 7 or 15 devices per SCSI bus)
- Support for almost any peripheral type (disk, tape, CDROM, scanner
- etc)
- All commands can overlap with commands on other devices Usually uses
- DMA to transfer data (which frees CPU for other tasks) Interface and
- protocol is carefully specified by ANSI.
- Largest, highest performance devices are available in SCSI before IDE
- Most adapters can do scatter/gather DMA which is a necessity in
- virtual memory systems (Like Unix, NT) (Win 95 ?)
-
- Cons of SCSI:
- Generally more expensive than IDE/ATA
- Slightly more complicated to install than IDE/ATA
-
- ---------------
-
- Now that I've said that, here's an article to show that there's more
- than one opinion on this subject:
-
- From: Ed Schernau <mithrandir@ids.net>
- Subject: FYI: EIDE and DMA/Scatter-Gather
- The Western Digital Caviar EIDE drive that came in what is now the
- file server in our office came with a Win3.x 32 BDA driver which
- allowed the user to select DMA type (B or F) and to implement
- scatter-gather.
- Also, the Intel Triton chipset implements 2 EIDE controllers, and I
- know that at least the 1 on the PCI bus supports bus-mastering, as
- well as DMA. However, PIO transfers can be faster, the infamous Mode
- 4 can in theory, do 16.6 MB/sec and I've heard of a Mode 5 which can
- do 22 MB/sec. Which [PIO] is only a benefit in single-tasking systems
- like DOS or Win3.x. Sounds like Intel is trying to make EIDE into
- SCSI, eh?
-
- Table of Contents
- ====
- Should I spend the extra money on SCSI or just get IDE?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- For home users this is a difficult question to answer in general.
- It totally depends on how you use your system, what operating system
- is
- installed, and whether you will add more I/O devices in the future.
- For server systems in a corporate environment the only sensible
- answer is to go with SCSI peripherals.
- IDE/EIDE is single threaded by nature. The current command must
- complete before additional commands can start. With most IDE adapters
- the processor must be involved in reading/writing the data from/to
- memory. Another drawback is that only two drives can be attached. In
- a single drive single-tasking system IDE will probably be slightly
- faster and is definitely less expensive.
- When you start talking about multi-tasking operating systems (like
- Win95, WinNT, Unix, OS/2 and Netware) SCSI is now a big advantage. As
- disk drives get bigger, backup devices are becoming even more
- important. In my opinion floppy tapes just aren't satisfactory.
- They're too slow, too unreliable, non-portable(media exchange wise
- not physically), and have low storage capacities. SCSI tape drives
- are more expensive, but have none of these problems. SCSI devices
- share the bus bandwidth efficiently by allowing one device to
- transfer data while another is seeking or rewinding its media. Early
- SCSI implimentations had some compatibility problems but these days
- SCSI is simpler to install than EIDE. Each user needs to make this
- choice individually, but if you don't consider all the issues, you
- can find yourself needing to re-vamp all your I/O to add a device
- later on. Before you decide to go with IDE, ask yourself if you will
- ever want to add a CDROM, CD-R, scanner, or tape drive or need more
- than two hard disk drives.
-
- Here's a discussion that shows some of the advantages of SCSI in more
- detail:
- from: Greg Smith (GREGS@lss-chq.mhs.compuserve.com)
-
- Under DOS (and DOS/win3.1), there is very little useful work the host
- can do while waiting for a disk operation to complete. So handing off
- some work from a 66 MHz 486 to, say, an 8 MHz Z80 (on the controller)
- does result in a performance loss. Under EVERY other OS worth
- discussing (Unix, Netware, NT, OS/2, Win95 etc) the processor can go
- off and do something else while the access is in progress, so the
- work done by the other CPU can result in a performance increase. In
- such systems, due to virtual memory, a 64K byte 'contiguous' read
- requested by a process may be spread to 16 separate physical pages.
- A good SCSI controller, given a single request, can perform this
- 'scatter/gather' operation autonomously. ATA requires significant
- interrupt service overhead from the host to handle this.
-
- Another big issue: ATA does not allow more than one I/O request to be
- outstanding on a single cable, even to different drives. SCSI allows
- multiple I/O requests to be outstanding, and they may be completed
- out of order. For instance, process 'A' needs to read a block.
- The request is sent to the drive, the disk head starts to move, and
- process 'A' blocks waiting for it. Then, process 'B' is allowed to
- run; it aslo reads a block from the disk. Process B's block may be
- sitting in a RAM cache on the SCSI controller, or on the drive
- itself. Or the block may be closer to the head than process A's
- block, or on a different drive on the same cable. SCSI allows process
- B's request
- to be completed ahead of process A's, which means that process B can
- be running sooner, so that the most expensive chip - the system CPU -
- tends to spend less time twiddling its thumbs. Under ATA, the process
- B
- request cannot even be sent to the drive until the process A request
- is complete. These SCSI capabilities are very valuable in a true
- multi-tasking environment, especialy important in a busy file server,
- and useless under DOS, which cannot take advantage of them.
- I tend to hear from people, 'Well, I never use multitasking' because
- they never actively run two programs at once û all but one are 'just
- sitting there'. Consider what happens though, when you minimize a
- window which uncovers parts of four other application windows. Each
- of those applications is sent a message telling it to update part of
- its window; under win95, they will all run concurrently to perform
- the
- update. If they need to access disk (usually because of virtual
- memory) the smoothness of the update can depend a lot on the disk
- system's ability to respond to multiple independent read requests and
- finish them all as quickly as possible; SCSI is better at this.
-
- So, yes, ATA is faster under DOS; but SCSI provides advantages which
- are inaccessible to DOS. They will benefit Win95 however. The cost of
- intelligent, fast SCSI controllers and drives should decrease as
- people
- discover these advantages and start buying them. I should add that
- many of SCSI's advantages are NOT available with some of the simpler
- SCSI controllers which were targeted only to the DOS market or part
- of cheap CDROM add-on kits.
-
- Furthermore, SCSI allows far greater flexibility of interconnect. I
- concede that for the mass market, which likes to buy pre-configured
- machines, this is but a small advantage.
-
- Table of Contents
- ====
- QUESTION: Can I have both IDE/ATA drives and SCSI in the same system?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- The short answer is YES. There are a few issues to consider however.
- The main issue is which device will be used for booting the system.
- Under MSDOS, The system BIOS determined this completely. A couple
- third party BIOSes (like MRBIOS) allowed the user to choose the boot
- source, but most conventional BIOSes just booted from the IDE if it
- was present. If no IDE was present then the standard option card BIOS
- scan would find the SCSI card's BIOS and use it to boot.
- Under Windows 95 and Windows NT, there are more options. Since the
- motherboard BIOS is used to load the boot sector that will still
- happen according to the same rules as under MSDOS described above.
- After the boot sector is loaded, the O/S's device drivers take over
- and those can be unloaded or drive letters re-ordered via the O/S
- configuration tools.
- Table of Contents
- ====
- QUESTION: Is it possible for two computers to access the same SCSI
- disks?
- ANSWER From: burke@seachg.uucp (Michael Burke)
- ====
-
- Yes, two (or more) systems can be on the same SCSI bus as SCSI disk
- and tape drives. As long as the SCSI requirements are met - cable
- lengths, termination and type - the devices can share the SCSI bus.
- [Editor(GF): Each host adapter needs to have a unique ID just as the
- devices do. Some adapters don't let you set this. ]
- The question should be - Are there any O/S' that will allow the
- sharing of file systems? It would not make sense for two hosts to go
- about treating shared disks as if they each owned the device. Data
- would be destroyed pretty quickly.
- [Editor(GF): CDROM drives can be shared pretty easily because they
- are by definition READ-ONLY]
-
- Disks can be best shared by having two (or more) partitions on a
- disk. Each host "owning" its own file system.
- [Editor(GF): You also need to watch out for host adapters that reset
- the bus when booting. Some adapters let you control this. ]
-
- [ Additional editorial comment Editor(GF):
- The above discussion refers primarily to PCs. There are high end
- systems that do allow sharing SCSI devices. Usually, this is to allow
- fault tolerance. Two systems are connected to the same set of SCSI
- storage devices and when one of them fails, the other takes control.
- AIX with HACMP, Digital UNIX, and Digital VMS are examples of systems
- that allow this.
- - Thanks to Cees de Groot for suggesting this addition.]
-
- Table of Contents
- ====
- QUESTION: Is it possible for two computers to access the same SCSI
- tape?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Yes, this is not usually as problematic as sharing disks as long as
- the operator is sensible about what is attempted.
- Some things you need to watch out for:
- Both host's device drivers must use RESERVE/RELEASE commands to lock
- access. This locks the drive for access by only one system, the
- conflicting host gets BUSY status until the currently accessing host
- sends a RELEASE cmd.
- The adapter on both hosts have unique IDs.
- Good and common grounding of both systems and the devices.
- SCSI length limits are not violated.
- Make sure both hosts select the same data transfer mode (synch or
- asynch).
- Both hosts can be told which disks and other devices to access and
- not to attempt to access the ones owned by the other host.
- Neither host adapter resets the SCSI bus.
- Table of Contents
- ====
- QUESTION: What is the problem with the Adaptec 1542C and external
- cables?
- ANSWER From: Scot Stelter, Adaptec (Product Manager for the AHA-1540)
- ====
- Several articles lately have cited the importance of SCSI-2-compliant
- cables when cabling SCSI bus subsystems. Perhaps the most accurate
- and technically detailed one was published in Computer Technology
- Review in March æ93 (Volume XIII, No. 3. PP. 6). In short, it
- explains the double-clocking mechanism that can occur due to cables
- whose impedance falls below the 90-Ohm SCSI-2 spec. Steep edge speeds
- on the REQ and ACK lines of the SCSI bus exacerbate the problem, but
- non-compliant cables are the root cause. Both LAN TIMES in the US
- (5/24/93, page 115) and CT Magazine in Germany (7/93, page 18) cite
- this cable problem.
- In an extensive survey of cables available in the US and Europe, we
- found that more than half of the cables available have single-ended
- impedances in the 65 to 80 Ohm range -- below the 90 to 132 Ohms
- specified in the SCSI-2 spec. It seems that some (not all) cable
- vendors do not understand the specification, describing their cables
- as SCSI-2 compliant when they are not. A common misconception is that
- SCSI-2 means a high-density connector. In fact, there are several
- connector options. I have published a technical bulletin that
- summarizes the critical requirements (TB 001, April 1993). An
- artifact of its faster design left the AHA-1540C with faster edge-
- speeds than its predecessor, the AHA-1540B. As I have said, this can
- exacerbate the effect of bad cables. This explains why some users
- could get their AHA-1540B to work when an early AHA-1540C might not.
- Essentially, the 1540B was more forgiving than the early 1540Cs. Good
- cables fixed the problem, but unfortunately for the user, good cables
- are hard to find.
- After surveying the cable market and many of our customers, we
- decided that bad cables were going to be here for a while, and we had
- to make the 1540C as forgiving as the 1540B was. At the end of April
- '93 we made a change to the AHA-1540C that involved using a passive
- filter to reduce the slew rate of the ACK line, the signal that the
- host adapter drives during normal data transfers. Extensive testing
- with many intentionally illegal configurations confirms that we
- succeeded. Prior
- to release, we tested the AHA-1540C with over 200 peripherals,
- systems and demanding software programs with no failures. Then, a
- second team retested the AHA-1540C across a wild combination of
- temperatures, humidities and other stresses. This testing gives me
- confidence that the AHA-1540 line continues to serve as the gold
- standard for SCSI compatibility.
-
- Table of Contents
- ====
- QUESTION: What is the difference between the Adaptec 1542A and 1542B?
- ANSWER From: fishman@panix.com (Harvey Fishman)
- ====
- The AHA-1542A is obsolete and no longer supported by Adaptec. They
- stopped providing firmware upgrades at some level prior to the
- equivalence to the 3.10 level of the AHA-1542B firmware. I am not
- sure just where though. The present latest AHA-1542B firmware is
- version 3.20, and supports drives up to 8GB under MS-DOS.
-
- Table of Contents
- ====
- QUESTION: What are the differences between the Adaptec 1542B and the
- 1542C?
- ANSWER from: Terry Kennedy (terry@spcvxa.spc.edu)
- ====
-
- The 1542C is an an updated model which replaces the 1542B. The 1542C
- features jumperless setup, having only 8 DIP switches. All other
- configuration options are set using the 1542C's built-in BIOS
- configuration utility. Configurable features not found on the 1542B
- are:
-
- Ability to enable/disable sync negotiation on a per-ID basis (the
- 1542B could only do it for all ID's on the SCSI bus)
- Ability to send "start unit" commands on a per-ID basis
- BIOS works with alternate I/O port settings on the adapter.
- Ability to boot from ID's other than 0
- Software-selectable termination
- Software-selectable geometry translation
- Additional DMA speeds of 3.3 and 10 MB/sec
-
- Additionally, the 1542C uses a Z80 CPU and 8Kb buffer instead of an
- 8085 and 2Kb buffer as on the 1542B.
-
- Table of Contents
- ====
- QUESTION: What are the differences between the 1542C and the 1542CF?
- ANSWER from: Terry Kennedy (terry@spcvxa.spc.edu)
- ====
-
- The 1542CF includes all of the 1542C features, and adds "Fast" SCSI
- operation, providing SCSI data rates of up to 10MB/sec (compared with
- an upper limit of 5MB/sec on the 1542C). This is unrelated to the
- host DMA rate. It also has a software configurable address for the
- floppy controller and a "self-healing" fuse for termination power.
-
- Table of Contents
- ====
- QUESTION: Where can I get SCSICNTL.EXE and other Adaptec files?
- ANSWER From: randy@psg.com (Randy Bush)
- and Timothy Hu timhu@ico.isc.com
- ====
-
- ftp.psg.com:~/pub/adaptec/...
-
- SCSICNTL.EXE.Z
- adse.dd
- adse.dd.readme
- list
- os2drv.zip
- scsi_drv.Z
- scsi_drv.readm
- update.pkg.Z
-
- "list" is a file that describes all the files in this directory.
- You can get the ASPI specs from Adaptec's Bulletin Board (408)945-
- 7727.
-
- [Editor(GF): You can also get ASPI spec's from Adaptec's WWW server.]
-
- Table of Contents
- ====
- QUESTION: What kinds of Optical Drives are available?
- The previousanswer From: joungwoo@mensa.usc.edu (John Kim) has been
- replaced with an updated version.
-
- ANSWER From: Psycho Bob <honge@creighton.edu>[Editor(GF)]
- DATE: Sep 18, 1996
- ====
- As magnetic recording approaches the current engineering limit, more
- and more attention is paid to optical storage solutions. Optical
- storage has good points going for it -- immunity to stray magnetic
- field, potential for higher storage capacity per unit area, and
- relatively low media cost.
-
- Although CD-ROM and CD-R are also optical storage units, they are not
- rewritable -- that puts them out as either secondary storage or
- primary
- backup storage for most of us. There is an upcoming sub-format called
- CD-E ("E" for erasable) that is suppose to become available in late
- 1996, but I haven't seen much news or even definite rumors. With the
- advent of DVD, the CD-E may only be a temporary stepping stone to
- recordable DVDs.
-
- Currently, the most popular magnetic storage format is magneto-
- optical
- (MO) format. It was the only popular rewritable optical storage disc
- technology before Panasonic's phase-change double-function (PD)
- format
- came out in 1995.
-
- Magneto-Optical
- As the name implies, MO uses both magnetic and optical technology to
- store data on the disc. The disc itself is rare earth metal
- substrate. When data is to be written, the particular spot is first
- heated by the laser to the Curie point, and the magnetic field is
- generated while the spot cools. By varying the magnetic field angle,
- the substrate is polarized in certain way that it will reflect the
- laser beam differently depending on the magnetic field angle when the
- particular spot was cooling down.
-
- MO comes in many sizes and capacities. Consumers were first exposed
- to
- MO in Steve Jobs' NeXT computer in the mid-1980s. Although 5.25" had
- a
- slow start due to initial high cost, it has been evolving quite
- nicely.
- The more popular ISO capacities for 5.25" MO are 2.4GB/2.6GB,
- 1.2GB/1.3GB, and the 600MB/650MB. In 3.5" form, MO is available in
- 540MB/640MB, 230MB, and the 128MB. There are also some 12" MO, 14"
- MO, and other odd sizes in odd capacities. But they are limited to
- niche markets.
-
- Sony MiniDisc-Data
- Derived from the Mini-Disc (MD) audio format Sony introduced, MD-Data
- is to MD as CD-ROM is to digital audio compact disc (CD-DA). MD-Data
- (and digital audio MD) is based on the same magneto-optical
- technology, which explains the high-cost of the consumer MD audio
- units.
-
- MD-Data is the smallest of the MO family. With 2.5" form factor, it
- can store 140MB of uncompressed data. Current MD-Data drives are
- rather slow at 150KB/sec sustained transfer rate, but Sharp is hoping
- to change that.
- Sharp will (hopefully) ship a 300KB/sec by the end of 1996, with a
- second generation of MD-Data available by sometime in 1997. The
- current schedule from Sharp indicates the second generation MD-Data
- will be able to store up to 700MB with 600KB/sec transfer rate.
-
- The most important technical advancement MD-Data brought for MO in
- general is the one-pass recording. Prior to 5.25" 2.4GB/2.6GB MO and
- 3.5" 540MB/640MB MO, almost all MO used two passes to write data onto
- the disc
- -- one pass to erase the whole track, and a second pass to write the
- updated data. MD's one pass recording, called light intensity
- modulation, direct over-write (LIM-DOW, ISO 14517) will be in almost
- all the future MO formats until another better technology comes
- along.
-
- Just like CD, MD-Data comes in various flavors -- rewritable, write-
- once, and read-only cartridges. There is also a hybrid disc for MD
- and MD-Data that is part read-only, and part rewritable.
-
- Panasonic phase-change double-function (PD)
-
- In around mid-'95, Panasonic released a proprietary optical storage
- format called phase-change double-function (PD) drive. The PD uses
- substrate that will reflect the light differently when heated to
- different temperatures. Write-once-read-multiple (WORM) drives were
- actually the first phase-change formats, but PD is the first
- *reversible* (that is, re-writable) phase-change format. Current PD
- stores 650MB per PD cartridge.
-
- Currently, PD's only advantage over its MO brethren is the PD drive's
- ability to read regular CD-DA and CD-ROMs. The PD rewritable
- cartridge is not usable in regular CD-ROM drives.
-
- WORM and CD-R
- Both write-once-read-multiple (WORM) and compact disc recordable (CD-
- R)
- are both write-once formats -- once you have written the data to the
- disc, the data cannot be changed. Put another way, the disc media can
- only be used once. For long term archival of data that need not be
- changed, it makes sense -- as CD-R media price is unbeatable [As of
- mid 1996, 650 MB CD-R media sells for $6 to $8 each or about 1 cent
- per MB!] . Current CD-R offers maximum of 650MB per disc.
-
- WORM was the first popular format for optical storage, before being
- eclipsed by MO. WORM is still used by big companies and the
- government for archival purposes since it has the characteristic of
- not being able to be altered wihout damaging the media (good audit
- trail).
- The new WORM formats being introduced are tending to be more
- proprietary. There is rarely any interchangability between different
- vendor's drives and media.
-
- During the WORM to MO transition, a curious format called continuous
- composite write-once (CCW) appeared. CCW cartridges function as WORM
- cartridges, writable using the installed base of WORM drives. But put
- it into MO drive, CCW cartridges becomes rewritable. Simply put, CCW
- is
- MO in WORM's clothing. Many of today's 5.25" MO drives still have the
- capability to read CCW cartridges.
-
- The future
- Almost all the formats mentioned above have future plans -- usually
- an
- "improved version" with faster and more storage capacity. The 5.25"
- MO camp is shooting for the 4.8GB/5.2GB range, with faster sustained
- transfer rate in writing data. 3.5" may double their 650MB soon by
- using both sides of the disc. PD may also double the storage space by
- using both sides of the disc. But currently it's doubtful as DVD has
- pretty much been finalized. It'll be interesting to see how Panasonic
- will interpret the PD in the DVD marketplace (DVD-PD?). DVD-RAM is
- rumored to use phase-change technology.
-
- The same goes for CD-E, the latecomer of the bunch. If the CD-E is
- truly playable in ordinary CD-ROM (and audio CD player), it'll
- probably become the optical storage standard in all but the high-
- capacity, high-end/server market.
-
- Format Phys. Capacity Bytes # of sides Capacity
- Standard
- size per disk per sector per side
-
- MO 1p 2.5" 140MB 2048/2336 single 140MB Sony
- MD-Data
- MO 2p 3.5" 128MB 512 single 128MB ISO/IEC
- 10090, ECMA 154
- MO 2p 3.5" 230MB 512 single 230MB ISO/IEC
- 13963, ECMA 201
- MO 1p 3.5" 540MB 512 single 540MB
- DIS(ISO/IEC) 15041
- 640MB 2048 single 640MB
- MO 2p 5.25" 600MB 512 dual 296MB ISO/IEC
- 10089
- 650MB 1024 dual 322MB ANSI
- X3.2121-1992
- MO 2p 5.25" 1GB 512 dual 463MB ISO
- 13481
- 1GB 1024 dual 510MB
- MO 2p 5.25" 1.2GB 512 dual 595MB ISO/IEC
- 13549
- 1.3GB 1024 dual 650MB ECMA
- 184
- MO 1p 5.25" 2.4GB 512 dual 2.298GB
- DIS(ISO/IEC) 14517
- 2.6GB 1024 dual 1.3GB
- MO 2p 5.25" 1.5GB 4096 dual 750MB
- Panasonic
-
- MO 1p 5.25" 4.6GB 1024 dual 2.3GB
- Pinnacle Micro "Apex"
- MO 12" 8GB Nikon
- MO 12" 3.2GB Sony
- MO 14" 6.8GB 1024 dual 3.4GB Kodak
- System 2000
- 10.2GB 1024 dual 5.1GB
- 14.8GB 1024 dual 7.4GB
- WORM 5.25" 2.6GB
- DIS(ISO/IEC) 15486
-
- WORM 5.25" 650MB single 650MB ISO/IEC
- 9171 Format A
- WORM 5.25" 470MB
- Panasonic
- 940MB
- 1.4GB
- WORM 12" 15GB Sony
- PD 1p 5.25" 650MB 4096 single 650MB
- Panasonic
- CD-R 5.25" 550MB 2048 single 553MB
- 650MB 2048 single 650MB
- CD-E 5.25" 650MB pending...
-
- *technology: 1p -- one-pass write
- 2p -- two-pass write
-
- Standards for storage are set by many organizations. International
- Standards Organization (ISO), European Computer Manufacturers
- Association (ECMA), Deutsche Institut fur Normung (DIN), Japanese
- Industrial Standards Committee (JISC), and American National
- Standards Institute (ANSI) set the main optical disc storage
- standards. The ISO standards take precedence over all other
- standards.
-
- In the above table, the heading defines one standard -- e.g. 5.25" MO
- 1.2GB/1.3GB has both ISO 13549 and ECMA 184 listed for it. IT IS NOT
- THAT 1.2GB FOLLOWS ISO 13549 AND 1.3GB FOLLOWS ECMA 184.
-
- Of CD standards...
- Funny as it seems, CD is actually considered as proprietary a format
- made by Sony and Phillips. The physical format for derivatives like
- CD-ROM and CD-R are "written in mutual agreement" in form of Red
- Book, Yellow Book, Orange Book, etc.
-
- Of bytes/sector and usability...
- As many of you might notice (especially on 5.25" MOs), there are
- different sized sectors. Many O/Ses assume one sector to contain 512
- bytes. If you buy any of the media that use different than 512
- byte/sector, you will need a software driver of some sort to use the
- media.
-
- In optical media, the sectors are "hard sectored" at factory -- in
- other words, you cannot change the number of sectors by reformatting
- (low-level formatting) them. Take the 5.25" 1.2GB/1.3GB MO for
- example again. The 1.3GB media is sectored at 1024 bytes per sector.
- So the 1.3GB media has total of 637,041 sectors (per side) on it. If
- you do not use a software driver and your operating system does not
- properly recognize it, the 1.3GB media will become a 650MB cartridge
- (~325MB per side)!!
- The safest bet is to use the 512 bytes/sector media. That should make
- the drive and media usable on most operating systems.
- Addendum: (11/15/96)
- Sony and Phillips have just announed finalization of compact disc
- re-writable (CD-RW), together with HP, Matsushita, etc. Long story
- short, the CD-RW uses phase-change media -- same as Panasonic
- proprietary PD format. Not only that, it also stores 650MB like PD.
- And also like the PD, the CD-RW media cannot be read in regular CD
- and CD-ROM drives (surprise!)!!
-
- So, the good news is that CD-RW is here. The bad news is that it's as
- proprietary as Panasonic's PD in compatibility with current installed
- base of CD and CD-ROM players.
-
- Table of Contents
- ====
- QUESTION: Where can I get various SCSI documentation?
- ====
- Thanks to John Lohmeyer of Symbios Logic, a number of SCSI related
- files are available for anonymous ftp.
-
- The archive contains a large amount of data relating to SCSI, and
- ESDI as well as SCSI-2, IPI, and Fiber Channel, as well as the last
- revision of the SCSI-1 and SCSI-2 standards before they went into
- publication by ANSI.
- This information server is maintained by Symbios Logic (formerly NCR
- Corp., formerly AT&T Global Information Solutions) in the hope of
- returning some value to the Internet community. It contains
- information about commercial products, and also about computing-
- related topics in which Symbios Logic as a company, or individuals
- therein, have interest and expertise.
- The information is accessible from several sources:
- SCSI BBS: (719) 574-0424
- anonymous ftp to ftp.symbios.com
- WWW: http://www.symbios.com/x3t10
-
- Table of Contents
- ====
- QUESTION: How can I find out about the emerging SCSI standards?
- ANSWER From: Milton Scritsmier (milton@arraytech.com)
- ====
-
- The X3T10 committee has opened up a WWW site. It has an overview of
- SCSI-3, as well as pointers to the WWW sites for the three serial
- interfaces (FC, SSA, and P1394), and a pointer to an online copy of a
- proposed SCSI-2 spec.
- Here is the original announcement:
- Subject: New X3T10 Home Page
- Date: Thu, 31 Aug 95 14:07:00 MDT
-
- With a LOT of help from Carey Harrington (Thank you!), X3T10 now has
- a World Wide Web home page. If you have a web browser, you may want
- to check out:
- http://www.symbios.com/x3t10
-
- John Lohmeyer, Chair X3T10 Technical Committee
-
- ANSWER #2 From: Gary Bartlett (garyb@abekas.com)
- A draft version of the SCSI-2 spec is in HTML form on the WWW at:
- http://abekas.com:8080/SCSI2/
-
- ANSWER #3 From: Gary Watson (trimm@netcom.com)
-
- Small Form Factor (SFF) Committee documents are available by
- FaxAccess at:
- (408) 741-1600 You will be asked to order documents by number.
- For example: to get information on the Single Connector Attach spec.
- The SCA-1 spec. is document #8015
- The SCA-2 spec. is document #8046
- document #8000 is and index to the other documents.
-
- [Editor(GF): you might try: http://playground.sun.com/pub/SCA/SCAR3-
- 2.txt ]
-
- This FaxAccess service is available to all, but please keep in mind
- that unless you have engineering-level understanding of peripheral
- interfaces, you _will_not_ be able to understand any of it and you
- are wasting your own time and the bandwidth of these resources. If
- you are trying to learn more about SCSI, you are better off reading
- the magazine articles and books listed elsewhere in this FAQ.
-
- The SCSI, SFF, SSA, and Fibre Channel reflectors:
- A list of these is available on the Symbios WWW site.
-
- "The SCSI, SFF, SSA, and Fibre Channel reflectors are for review
- and commentary on the respective specifications, not for asking
- questions about the interfaces (unless related to a specific
- ambiguity in a specification) nor for recruiting nor for technical
- support nor any purpose other than what is stated. The reflectors
- _are_ available for public review and commentary as required by
- ANSI and ISO."
-
- Any spec on the reflectors or on the bbs or on the ftp sites are
- **proposed** or **preliminary** and are often subject to major
- substantive changes during the committee process. Actual, released,
- final specs are *only* available from Global Engineering Documents.
-
- ANSWER #4 From: Gary Field(gfield@zk3.dec.com)
-
- For Fibre Channel Association:
- http://www.fibrechannel.com/
-
- Table of Contents
- ====
- QUESTION: Where can I get official ANSI SCSI documents?
- ANSWER #1 From: kev@hpcpbla.bri.hp.com (Kevin Jones)
- and jmatrow@donald.WichitaKS.NCR.COM (John Matrow)
- ====
-
- The SCSI specification: Available from:
-
- ANSI
- 11 West 42nd St. - 13th floor
- New York, NY 10036
- Sales Dept. (212) 642-4900
-
- OR
-
- Global Engineering Documents
- 15 Inverness Way East
- Englewood Co 80112-5704
- (800) 854-7179 or (303) 792-2181
- Int'l Sales Fax: (303) 397-2740
-
- SCSI-1: X3.131-1986
- SCSI-2: X3.131-199x
- SCSI-3 X3T9.2/91-010R4 Working Draft
-
- [Editor(GF):] The official ANSI standards are NOT available free of
- charge from any source. Only draft versions are freely distributable.
-
- Table of Contents
- ====
- QUESTION: What SCSI books and tutorials are available?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
-
- IN-DEPTH EXPLORATION OF SCSI can be obtained from Solution
- Technology, Attn: SCSI Publications, POB 104, Boulder Creek, CA
- 95006, (408)338-4285, FAX (408)338-4374
-
- THE SCSI ENCYLOPEDIA and the SCSI BENCH REFERENCE can be obtained
- from ENDL Publishing, 14426 Black Walnut Ct., Saratoga, CA 95090,
- (408)867-6642, FAX (408)867-2115
-
- SCSI: UNDERSTANDING THE SMALL COMPUTER SYSTEM INTERFACE was published
- by Prentice-Hall, ISBN 0-13-796855-8 (Seems to be out of print)
-
- A neat little book called "Basics of SCSI" second edition, was sent
- to me free of charge by Ancot Corporation, Menlo Park, CA (415) 322-
- 5322. It gives a simplified description of how most aspects of the
- SCSI bus work and includes some discussion of SCSI-2 issues.
-
-
- "The book of SCSI - A guide for Adventurers" by Peter M. Ridge.
- Published by No Starch Press, Daly City, CA,
- ISBN # 1-886411-02-6, List Price $34.95.
- Contains general coverage of most aspects of SCSI.
- http://www.nostarch.com/scsi.htm
-
- "Programmer's Guide to SCSI" with CDROM - by Brian Sawert.
- Published by Addison Wesley, Reading, MA. SRP $39.95
- ISBN # 0-201-18538-5
- Includes a chapter on UNIX SCSI subsystems written by Gary Field.
- http://cseng.awl.com/bookdetail.qry?ISBN=0-201-18538-5&ptype=0
-
-
- Addition by: (kyrrin2@wizards.net)
- 'The SCSI Bus and IDE Interface' 2nd edition by Friedhelm Scmidt,
- Addison-Wesley Publishing, $34.95 (I think). It includes a diskette
- with examples of source code to handle SCSI and IDE devices from a
- low-level programmer's perspective, and it has very detailed
- technical descriptions of both subsystems.
- Not a book for beginners, but I heartily recommend it for anyone
- who's serious about learning the technical ropes.
-
-
- ANSWER #2 From: Runar Jorgensen (runar.jorgensen@fys.uio.no)
-
- There was a two part article in Byte Magazine. The first part was in
- Feb 1990 issue, p. 267-274 and the second was in Mar 1990 issue, p.
- 291-298.
- Another two part article appeared in Byte in May 1986 and June 1986.
-
- Table of Contents
- ====
- QUESTION: Where can I find SCSI info on the Web?
- ANSWER FROM: Gary Field (gfield@zk3.dec.com)
-
- Try some of these:
-
- http://www.delec.com/Tech_Links/SCSIGuide/
-
- http://www.quantum.com/src/
-
- Table of Contents
- ====
- QUESTION: Where can I get information on various disk drives and
- controllers?
- ANSWER: ekrieger@quasar.xs4all.nl (Eric Krieger) (Updated Sep. 30,
- 1994)
- ====
-
- Drive and Controller Guide, Version 4.3
-
- THEREF(tm) is a comprehensive Directory of Hard Drives, Floppy
- Drives,
- Optical Drives, and Drive Controllers & Host Adapters. It is designed
- to help the novice and pro alike with integration problems and system
- setups.
-
- Information is provided in two handy formats; Portrait mode, for
- those
- who prefer a normal book-binding type print format, and(or) do not
- have a printer with Landscape capability. And Landscape mode, for
- those who pre-fer a computer-printout type format.
-
- For printing, a Laserjet is preferred, but not necessary, and setup
- info is provided. For viewing, LIST(tm) by Vernon Buerg, will provide
- an excellent result, and allow text searches for finding specific
- models.
-
- By F. Robert Falbo
-
-
- Due many reports about the unavailablity of this file/archive I made
- sure that the file does exist at the following site:
-
- ftp://ftp.funet.fi
-
-
-
- you should find the archive at:
-
- /pub/doc/hardware/harddisks/theref43.tar.gz
- /pub/doc/hardware/harddisks/theref43.readme
-
- (In that directory-path there is also a sub-directory Seagate, where
- you also can find info/files about Seagate-drives).
-
- Before you actually get this file, be sure to get/read the file
- /README.FILETYPES since it explains the used file-extension and which
- (de-)archiver should be used (and where to find/get them!).
-
- Note: In the archive there are files containing Extended ASCII or
- ANSI characters (mostly used with IBM- and compatible PC's),
- so it may be a bit unreadable when reading it on non-PC
- systems, or without using a proper Characterset/Font!
-
- TheRef is also available via WWW from:
- http://theref.c3d.rl.af.mil
-
- Table of Contents
- ====
- QUESTION: Where can I get technical information and jumper settings
- for HP drives ?
- ANSWER From: Rodney Brown (RBrown@cocam.com.au)
- Update From: Martin C Mueller (mcm@mathematik.uni-kl.de )
- ====
-
- HP SCSI Storage Device Support Pages
- http://www.hp.com/isgsupport/index.html
-
- Table of Contents
- ====
- QUESTION: How can I contact Adaptec?
- Also: Future Domain, Corel CD Creator, Trantor, Incat systems,
- Symbios Logic.
- ANSWER From: jcaples@netcom.com (Jon D Caples)
- ====
-
- 408 945-8600 Main number
- 800 959 7274 tech support
- 800 442 7274 orders, doc, new bios, etc.
- 408 945-7727 BBS
-
- Adaptec's general inquiry number, 800-959-7274, affords access to a
- FAX-based information retrieval system. In order to preserve the
- accuracy of this information, I won't go into details about how to
- use it (since Adaptec may change things without telling me :) ).
-
- For those outside the CAN-US area, or local to Adaptec the
- direct
- FAX info number is (408) 957-7150.
-
- There are three general topics as of this writing:
-
- General Information
- Sales Information
- Technical Information
-
- Give it a call and request the directory! As of this writing
- there are over 130 documents available. You need a touchtone phone
- and the fax number. You'll also be asked for an extension number to
- stamp on the FAX which will be used to identify the recipient.
-
- [Editor(GF): As of July 1993 Adaptec bought Trantor.
- Try (800) 872-6867 (TRA-NTOR)]
- [Editor(GF): As of Feb. 19, 1998, Adaptec bought Symbios Logic]
-
- World Wide Web (WWW) URL:
- http://www.adaptec.com/
-
- [(from: Andrew Lockhart (andrew@interact.manawatu.planet.co.nz) ]
- You can address Adaptec support by email. The address is
- support@adaptec.com. An auto-responder will bounce a message back
- acknowledging receipt of your email. This message will also detail
- other current forms of Adaptec Technical support. They promise a, no
- more than, 5 day turn-around. We have found the response brief, but
- satisfactory to our needs. We should add, we mention we are Dealers
- in our email (which may improve AdaptecÆs response).
-
- Table of Contents
- ====
- QUESTION: How can I contact Archive Corporation?
- ====
-
- [Editor(GF)]
- Archive was bought by Conner Peripherals in 1993
-
- Table of Contents
- ====
- QUESTION: How can I contact BusLogic /Bustek / Mylex ?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Mylex Corp.
- 34551 Ardenwood Blvd.
- Fremont, CA 94555
- (510) 796-6100
-
- Tech. Support:
- Voice: (510) 608-2400
- FAX: (510) 745-7715
- Email: for HBA: techsup@mylex.com
- For RAID: support@mylex.com
-
- WWW: http://www.mylex.com/
-
- Table of Contents
- ====
- QUESTION: How can I contact Corel?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
-
- Main Number: (800) 772-6735
- Tech. Support: (613) 728-1010
-
- ANSWER From: Gerrit Visser (gerrit@isgtec.com)
- ====
- WWW: http://www.corel.ca/
-
- ftp: ftp.corel.ca: /pub SCSI is under Multimedia
-
- For Corel CD Creator Software contact Adaptec
-
- Table of Contents
- ====
- QUESTION: How can I contact Fujitsu?
- ANSWER From: Ken Porter (72420.2436@compuserve.com)
- ====
- Fujitsu FactsLine FAX Back service (408) 428-0456
- A six page catalog of available documents can be ordered.
-
-
- ANSWER From: Mike Henry (anonymous)
-
- A while back, Fujitsu created a product called
- Fujitsu Knowledge System (FKS) (long available on Compuserve
- (GO FUJITSU)). It is a Windows Help File (.HLP) listing
- of many Fujitsu disk, tape, and optical products.
-
- It includes drive switch/jumper settings and meanings
- (lot of posts requesting this info).
-
- It is available via anonymous ftp
- from ftp.intellistor.com
- in the /pub/fks directory
- filename: fks.exe
-
- It is self-extracting and mostly self-documenting.
-
- Table of Contents
- ====
- QUESTION: How can I contact Quantum?
- ANSWER From: kmartine@qntm.com (Kevin Martinez)
- ====
-
- Quantum Corporation
- 500 McCarthy Blvd.
- Milpitas, CA
- 95035
-
- Technical Support Telephone Numbers:
-
- 800 826-8022 Main Technical Support Number
- 408 894-3282 Technical Support Fax
- 408 894-3214 Technical Support BBS V.32 8N1
- 408 434-9262 Technical Support for Plus Development Products
- 408 894-4000 Main Quantum Phone number
-
- 800 4DISKFAX FAX on demand (From Thanh Ma tma@encore.com)
-
- WWW: http://www.quantum.com/
-
- Table of Contents
- ====
- QUESTION: How can I contact Seagate?
- ANSWER From: landis@sugs.tware.com (Hale Landis)
- ====
-
- Here are the numbers for Seagate's Technical Support.
-
- SeaBOARD - Bulletin Board System available 24 hours. Use 8 data
- bits, no parity, 1 stop bit (8-N-1).
-
- USA/Canada 408-438-8771 9600 baud*
- England 44-62-847-8011 9600 baud*
- Germany 49-89-140-9331 2400 baud*
- Singapore 65-292-6973 9600 baud*
- Australia 61-2-756-2359 9600 baud*
-
- * - Maximum baud rate supported.
-
- SeaFAX 408-438-2620
-
- Use a touch-tone phone to have information returned to you via
- FAX. Available 24 hours.
-
- Technical Support Fax 408-438-8137
-
- FAX your questions or comments 24 hours. Responses are sent
- between 8:00AM and 5:00PM PST Monday through Friday.
-
- SeaFONE 408-438-8222
-
- Provides recorded information 24 hours or talk to a technical
- specialist between 8:00AM to 5:00PM PST Monday through Friday.
-
- SeaTDD 408-438-5382
-
- Using a Telecommunications Device for the Deaf, you can send
- questions or comments 24 hours or have a dialog with a
- technical support specialist between 8:00AM and 5:00PM PST
- Monday through Friday.
-
- WWW: http://www.seagate.com/
-
- Table of Contents
- ====
- QUESTION: How can I contact Conner Peripherals?
- ====
-
- Conner Peripherals was bought by Seagate
-
-
- Table of Contents
- ====
- QUESTION: How can I contact Maxtor?
- ANSWER From: David G North (D_North@tditx.com)
- ====
-
- Main Number: (800) 262-9867 (Has FAXback feature for drive info etc)
- ftp site: ftp.maxtor.com (New!)
-
- ANSWER From: Eric Van Buren
- (vanburen%flovax.dnet@rocdec.roc.wayne.edu)
- ====
- WWW: http://www.maxtor.com/
-
-
- Table of Contents
- ====
- QUESTION: How can I contact NCR?
- ====
-
- NCR Microelectronics division was bought by AT&T and then by Symbios
- Logic.
-
- See "How can I contact Symbios Logic"
- As of Feb 19, 1998, Hyundai agreed to sell Symbios to Adaptec.
-
- Table of Contents
- ====
- QUESTION: How can I contact Philips?
- ANSWER From: S. C. Mentzer (smentzer@anes.hmc.psu.edu)
- ====
-
- Philips Consumer Electronics Co.
- One Philips Drive
- Knoxville, TN 37914-1810
- (615) 521-4316
- (615) 521-4891 (FAX)
-
- [Editor(GF)]
- WWW: http://www.philips.com/
-
- Table of Contents
- ====
- QUESTION: How can I contact Symbios Logic?
- Answer From: Symbios Logic
- Update From: Wade Adams (link@vantek.net)
- ====
- Symbios is a wholly owned subsidiary or Hyundai Elecctronics.
- For literature on any Symbios Logic product please contact:
- Phone: (800) 636-8022
- (800) 856-3093
- (719) 536-3300
- Fax: (719) 536-3301
- email: literature@symbios.com
-
- Technical Support:
- Phone: (719) 533-7230
- WWW: http://www.symbios.com/
-
- Table of Contents
- ====
- QUESTION: How can I contact UltraStor? (Out of business)
- Answer From: Ultrastor
- ====
-
- UltraStor Corporation
- 13766 Alton Parkway suite 144
- Irvine, CA 92718
-
- General (714) 581-4100
- Tech. Support (714) 581-4016
- FAX (714) 581-4102
- BBS (714) 581-4125
-
- email: ultrastor@primenet.com
- finger: ustor@primenet.com
- ftp: ftp.primenet.com:users/u/ustor
-
- ====
- Answer From: Ben Mehling (bmehling@uci.edu)
- ====
- I am setting up a "unauthorized" UltraStor site for the orphaned
- customers and
- cards still out there.
-
- I do not think the above numbers are good anymore.
- The 4100 line will get you Power I/O (an unrelated Adaptec holding)
- and the 4016 line may get you a dead-end answering
- service. The company is no longer active (as far as I know). The
- primenet account is alive, but again not active. These links are to
- the "Unauthorized" UltraStor site. This site is in no way affiliated
- with UltraStor or its holding companies. It is a free "mirror" site
- for distribution of drivers and information. (hint: we are trying to
- help out, not provide tech support.)
- Try:
-
- UltraStor@kuci.uci.edu (unauthorized).
- www.UltraStor (unauthorized).
- ftp.UltraStor (unauthorized).
-
- The above three addresses are hypertext linked to these addresses:
-
- The web site address is: www.kuci.uci.edu/~ustor
- The FTP site address is: falco.kuci.uci.edu/users/ustor
- The mail/finger address is ultrastor@kuci.uci.edu /
- ustor@falco.kuci.uci.edu
-
- The current maintainers are:
-
- Ben Mehling (bmehling@uci.edu)
- Phil Colline (pcolline@falco.kuci.uci.edu)
-
-
- Table of Contents
- ====
- QUESTION: How can I contact Tecmar Technologies (formerly Wangtek,
- WangDAT, Sytron, and Rexon)?
- ANSWER FROM: from: Jay Long - (jayl@mfltd.co.uk) and
- Peter Dyballa (pete@riese.thi.informatik.uni-frankfurt.de)
- ====
-
- Tecmar Technologies, Inc.
- 1900 Pike Rd., Bldg. E
- Longmont, CO USA
- phone: (303) 682-3700
- (303) 776-7706
- FAX: (303)776-1085
- faxback: (800) 4BACKUP
-
- WWW: http://www.tecmar.com/
-
- European Office
- Unit 15 Suttons Business Park
- Suttons Park Avenue
- Earley, Reading, UK RG6 1AZ
- (44) 1189-660063
- (44) 1189-660065 FAX
-
- Singapore Office
- Blk. 35 Marsiling Industrial Estate Road 3 #05-01/ 06
- Singapore 739257
- (65) 269-2228
- (65) 360-0888 fax
-
- Table of Contents
- ====
- QUESTION: How can I contact Western Digital?
- ANSWER From: FILIPG@PARANOIA.COM
- ====
- Address:
- Western Digital Corporation
- 8105 Irvine Center Drive
- Irvine, CA USA 92718
-
- Online Services:
- Tech Support BBS 714-753-1234 (up to 28.8 KBS)
- WWW: http://www.wdc.com/
- FTP ftp.wdc.com
- AOL (keyword) WDC or Western Digital
- MSN (go word) WDC
-
- Table of Contents
- ====
- QUESTION: How can I contact DPT (Distributed Processing Technology)?
- ANSWER: From: Gary Field (gfield@zk3.dec.com)
- ====
-
- voice: (407) 830-5522
- FAX: (407) 260-6690
-
- [Editor(GF)]
- WWW: http://www.dpt.com/
-
- Table of Contents
- ====
- QUESTION: How can I contact Micropolis?
- ANSWER: From: Richard Ravich (Richard_Ravich@microp.com)
- ====
-
- Tech Support: (818) 709-3325
- email: Richard_Ravich@microp.com
- WWW: http://www.micropolis.com/
-
- [Editor(GF): I believe that Micropolis is now (late 1997) out of
- business û RIP. You might try http://www.blue-planet.com/tech/ for
- drive info. ]
-
- Table of Contents
- ====
- QUESTION: How can I contact Legacy Storage Systems ?
- ANSWER: From: Gregory Smith (GREGS@lss-chq.mhs.compuserve.com)
- ====
-
- General: (905) 475-1077
- Sales/Tech support/Service: (905) 475-0550
- U.S. Tech Support: (800) 361-5685
- Fax: (905) 475-1088
-
- Mail:
- Legacy Storage Systems
- 43 Riviera Drive
- Markham, ON Canada L3R 5J6
-
- Table of Contents
- ====
- QUESTION: what is FAST SCSI?
- ANSWER From: kev@hpcpbla.bri.hp.com (Kevin Jones)
- ====
-
- There are 2 handshaking modes on the SCSI bus, used for transferring
- data:
- ASYNCHRONOUS and SYNCHRONOUS.
- ASYNCHRONOUS is a classic Req/Ack handshake.
- SYNCHRONOUS is "sort of" Req/Ack, only it allows you to issue
- multiple Req's before receiving Ack's. What this means in practice is
- that SYNCHRONOUS transfers are approx 3 times faster than
- ASYNCHRONOUS.
-
- SCSI1 allowed asynchronous transfers at up to 1.5 Mbytes/Sec and
- synchronous transfers at up to 5.0 Mbytes/Sec.
-
- SCSI2 had some of the timing margins "shaved" in order that faster
- handshaking could occur. The result is that asynchronous transfers
- can run at up to 3.0 Mbytes/Sec and synchronous transfers at up to
- 10.0 Mbytes/Sec.
- The term "FAST" is generally applied to a SCSI device which can do
- syncrhonous transfers at speeds in excess of 5.0 Mbytes/Sec. This
- term can only be applied to SCSI2 devices since SCSI1 didn't have the
- timing margins that allow for FAST transfers.
-
-
- Table of Contents
- ====
- QUESTION: How can I check a passive SCSI terminator?
- ANSWER From: stevel@coos.dartmouth.edu (Steve Ligett)
- ====
- With an Ohmmeter:
- The terminator contains 18 220-ohm resistors from signals to TERMPWR,
- and 18 330-ohm resistors from those signals to GROUND. I've drawn
- that below:
- TERMPWR
- --+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- | | | | | | | | | | | | | | | | | |
- R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1
- | | | | | | | | | | | | | | | | | |
- sig o o o o o o o o o o o o o o o o o o
- | | | | | | | | | | | | | | | | | |
- R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2
- | | | | | | | | | | | | | | | | | |
- --+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- GROUND
-
- R1 = 220 Ohms, R2 = 330 Ohms
-
- When you measure from any one signal to termpower, you aren't
- measuring that resistor in isolation, you are measuring that resistor
- IN PARALLEL with the combination of the corresponding 330 ohm
- resistor plus 17 220+330 ohm resistor pairs in series.
-
-
-
- I've redrawn the schematic to
- make this easier to see:
-
- TERMPWR
- /+---+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- | | | | | | | | | | | | | | | | | |
- | R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1 R1
- | | | | | | | | | | | | | | | | | |
- | o o o o o o o o o o o o o o o o o
- | | | | | | | | | | | | | | | | | |
- | R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2
- | | | | | | | | | | | | | | | | | |
- | --+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- | / GROUND
- R1 |
- | |
- | R2
- | /
- o <--------- 17 other pairs in parallel ---------->
- sig
- We're trying to measure that one resistor from a signal to TERMPWR,
- but there's a ton of other stuff in parallel. The resistance of that
- "stuff" is 330 + 550/17 ohms (the 330 ohm resistor, in series with a
- parallel combination of 17 550 ohm resistors). The general formula
- for the equivalent of two resistances in parallel is r1*r2/(r1+r2).
- Whipping out my trusty spreadsheet, I find that the "stuff" has a
- resistance of about 362 ohms, and that, in parallel with 220 ohms is
- about 137 ohms.
-
- Table of Contents
- ====
- QUESTION: Can someone explain to me the difference between 'normal'
- SCSI and differential SCSI?
- ANSWER From: ralf@wpi.WPI.EDU (Ralph Valentino)
- ====
- "Normal" SCSI is also called "Single-ended" SCSI. For each signal
- that needs to be sent across the bus, there exists a wire to carry
- it. With differential SCSI, for each signal that needs to be sent
- across the bus, there exists a pair of wires to carry it. The first
- in this pair carries the same type of signal the single-ended SCSI
- carries. The second in this pair, however, carries its logical
- inversion. The receiver takes the difference of the pair (thus the
- name differential), which makes it less susceptible to noise and
- allows for greater cable length.
-
-
- Table of Contents
- ====
- QUESTION: What are the pinouts for differential SCSI?
- ANSWER From: ralf@wpi.WPI.EDU (Ralph Valentino)
- ====
- Differential SCSI Connector Pinouts
- ---------------------------------------- ----------------------------
- ------------
- | SCSI | | MINI | | | SCSI | | MINI
- | |
- | SIGNAL | DD-50P | MICRO | DD-50SA | | SIGNAL | DD-50P | MICRO
- | DD-50SA |
- ---------------------------------------- ----------------------------
- ------------
- | -GND | 2 | 26 | 34 | | (open) | 1 | 1
- | 1 |
- | -DB(0) | 4 | 27 | 2 | | +DB(0) | 3 | 2
- | 18 |
- | -DB(1) | 6 | 28 | 19 | | +DB(1) | 5 | 3
- | 35 |
- | -DB(2) | 8 | 29 | 36 | | +DB(2) | 7 | 4
- | 3 |
- | -DB(3) | 10 | 30 | 4 | | +DB(3) | 9 | 5
- | 20 |
- | -DB(4) | 12 | 31 | 21 | | +DB(4) | 11 | 6
- | 37 |
- | -DB(5) | 14 | 32 | 38 | | +DB(5) | 13 | 7
- | 5 |
- | -DB(6) | 16 | 33 | 6 | | +DB(6) | 15 | 8
- | 22 |
- | -DB(7) | 18 | 34 | 23 | | +DB(7) | 17 | 9
- | 39 |
- | -DB(P) | 20 | 35 | 40 | | +DB(P) | 19 | 10
- | 7 |
- | GND | 22 | 36 | 8 | |DIFSENS | 21 | 11
- | 24 |
- | GND | 24 | 37 | 25 | | GND | 23 | 12
- | 41 |
- |TERMPWR | 26 | 38 | 42 | |TERMPWR | 25 | 13
- | 9 |
- | GND | 28 | 39 | 10 | | GND | 27 | 14
- | 26 |
- | -ATN | 30 | 40 | 27 | | +ATN | 29 | 15
- | 43 |
- | GND | 32 | 41 | 44 | | GND | 31 | 16
- | 11 |
- | -BSY | 34 | 42 | 12 | | +BSY | 33 | 17
- | 28 |
- | -ACK | 36 | 43 | 29 | | +ACK | 35 | 18
- | 45 |
- | -RST | 38 | 44 | 46 | | +RST | 37 | 19
- | 13 |
- | -MSG | 40 | 45 | 14 | | +MSG | 39 | 20
- | 30 |
- | -SEL | 42 | 46 | 31 | | +SEL | 41 | 21
- | 47 |
- | -C/D | 44 | 47 | 48 | | +C/D | 43 | 22
- | 15 |
- | -REQ | 46 | 48 | 16 | | +REQ | 45 | 23
- | 32 |
- | -I/O | 48 | 49 | 33 | | +I/O | 47 | 24
- | 49 |
- | GND | 50 | 50 | 50 | | GND | 49 | 25
- | 17 |
- ---------------------------------------- ----------------------------
- ------------
-
- Please note that I can only verify the DD-50P connector. The Mini
- Micro and DD-50SA pinout above is a pin for pin mapping from the SCSI
- pinout in this FAQ.
- ====
- How can I tell if I have a single ended or a differential drive?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Most times the model number of the drive will end with "D".
- Use an ohm meter to check the resistance between pins 21 & 22.
- On a single ended system, they should both be tied together and tied
- to GND.
- On the differential drive, they should be open or have a significant
- resistance between them. Differential drives are less common than
- single-ended ones, because they are mainly used only where longer
- cable runs are necessary, and they are not generally used in PCs, but
- state of the art drives are available with differential interfaces.
- Generally only the higher performance drives have a differential
- option because of the added cost.
-
- Table of Contents
- ====
- QUESTION: Who manufactures SCSI extenders and Single-Ended to
- Differential converters ?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
-
- The following companies manufacture SCSI extenders and converters:
-
- Ancot Corporation
- 115 Constitution Drive
- Menlo Park, CA 94025
- Tel: (415) 322-5322
- Fax: (415) 322-0455
- Email: sales@ancot.com
- URL: http://www.ancot.com/
-
- Apcon Inc.
- 17938 SW Boones Ferry Road
- Portland, OR 97224
- Phone: (503) 639-6700 Fax: (503) 639-6740
- Email: info@apcon.com
- URL: http://www.apcon.com/
-
- Paralan Corporation
- 7875 Convoy Court, San Diego, CA 92111
- Tel. (619) 560-7266 || Fax 619-560-8929
- WWW: http://www.paralan.com/
- email: scsi@paralan.com
-
- Rancho Technology Inc.
- 10783 Bell Court-Rancho
- Cucamonga-CA-91730
- Phone: (909)987-3966; Fax: (909)989-2365;
- E-Mail: scsi@rancho.com; BBS: (909)980-7699
- URL: http://www.rancho.com/
-
-
-
-
- Table of Contents
- ====
- QUESTION: I've got a SCSI disk with an 80 pin connector. Someone
- called it an SCA drive. Can I connect this to my SCSI bus?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- SCA Stands for "Single Connector Attachment". It is a standard being
- worked on by the ANSI Small Form Factor (SFF) committee. It combines
- WIDE SCSI signals, Power connections and ID switch connections onto
- one connector. SCSI vendors sell adapters that bring out the three
- sets of signals to conventional connectors.
- See: http://playground.sun.com/pub/SCA/SCAR3-2.txt for more
- information about SCA.
-
- Table of Contents
- ====
- QUESTION: What are the pinouts for SCSI connectors?
- ANSWER From: snively@scsi.Eng.Sun.COM (Bob Snively)
- [ Edited and expanded by Gary Field (gfield@zk3.dec.com) ]
- ====
-
- Originally dated May 23, 1990
- The connector families described by the drawings have standard pin
- numberings which are described the same way by all vendors that I
- have encountered. The SCSI-2 specification identifies the standard
- numbering, using that convention. It happened to be documented by
- AMP, but all the vendors use the same convention.
-
- The following diagrams have the outline drawings of connector sockets
- at the bottom. This is really for reference only, because the
- connector sockets and plugs are both specified as to their numbering
- and usually are labeled.
-
- There are some minor problems in naming the microconnector conductor
- pairs, which I have corrected in the enclosed diagram. All the
- conductor pairs of the Mini-Micro (High Density) connector are in
- fact passed through on the cables. SCSI-2 defines the RSR (Reserved)
- lines as may be ground or may be open, but they are still passed
- through the cable. Most present standard SCSI devices will ground
- those lines.
-
-
- -------------------- microSCSI to SCSI Diagram ----------------------
- -----
-
-
- SCSI Connector Pinouts (single-ended)
-
- ------------------------------------ --------------------------------
- -----
- | SCSI | | MINI | | | SCSI | | MINI |
- |
- | SIGNAL| DD-50P | MICRO | DD-50SA | | SIGNAL | DD-50P | MICRO | DD-
- 50SA |
- ------------------------------------ --------------------------------
- -----
- | -DB(0)| 2 | 26 | 34 | | GND | 1 | 1 | 1
- |
- | -DB(1)| 4 | 27 | 2 | | GND | 3 | 2 | 18
- |
- | -DB(2)| 6 | 28 | 19 | | GND | 5 | 3 | 35
- |
- | -DB(3)| 8 | 29 | 36 | | GND | 7 | 4 | 3
- |
- | -DB(4)| 10 | 30 | 4 | | GND | 9 | 5 | 20
- |
- | -DB(5)| 12 | 31 | 21 | | GND | 11 | 6 | 37
- |
- | -DB(6)| 14 | 32 | 38 | | GND | 13 | 7 | 5
- |
- | -DB(7)| 16 | 33 | 6 | | GND | 15 | 8 | 22
- |
- | -DB(P)| 18 | 34 | 23 | | GND | 17 | 9 | 39
- |
- | GND | 20 | 35 | 40 | | GND | 19 | 10 | 7
- |
- | GND | 22 | 36 | 8 | | GND | 21 | 11 | 24
- |
- | RSR | 24 | 37 | 25 | | RSR | 23 | 12 | 41
- |
- |TERMPWR| 26 | 38 | 42 | | OPEN | 25 | 13 | 9
- |
- | RSR | 28 | 39 | 10 | | RSR | 27 | 14 | 26
- |
- | GND | 30 | 40 | 27 | | GND | 29 | 15 | 43
- |
- | -ATN | 32 | 41 | 44 | | GND | 31 | 16 | 11
- |
- | GND | 34 | 42 | 12 | | GND | 33 | 17 | 28
- |
- | BSY | 36 | 43 | 29 | | GND | 35 | 18 | 45
- |
- | -ACK | 38 | 44 | 46 | | GND | 37 | 19 | 13
- |
- | -RST | 40 | 45 | 14 | | GND | 39 | 20 | 30
- |
- | -MSG | 42 | 46 | 31 | | GND | 41 | 21 | 47
- |
- | -SEL | 44 | 47 | 48 | | GND | 43 | 22 | 15
- |
- | -C/D | 46 | 48 | 16 | | GND | 45 | 23 | 32
- |
- | -REQ | 48 | 49 | 33 | | GND | 47 | 24 | 49
- |
- | -I/O | 50 | 50 | 50 | | GND | 49 | 25 | 17
- |
- ------------------------------------ --------------------------------
- -----
- * NC = NOT CONNECTED
- CONNECTOR TYPES:
- DD-50SA
- ________________________ MINI-MICRO
- DD-50P | ------------------- |
- ______________________
- ______ ______ |17 \. . . . . . . . . /1 | |
- _________________ |
- 49| . . . . . .| 1 |33 \. . . . . . . . /18 | | 1\ - - - - - -
- - /25 |
- 50| . . . . . .|2 |50 \. . . . . . . / 34 | | 26\- - - - - -
- -/50 |
- ------------- | ------------- | | -----------
- -- |
- ------------------------- ---------------
- -------
- ribbon cable Old style Sun SCSI "SCSI-2"
- male male
-
-
- __________________
- ( 1 25 )
- \ ++++++++++++++ /
- \ 26 50/
- --------------
- "Centronics" 50 male (use pin numbers for MINI-MICRO)
-
- (VIEWED FROM FACE OF CONNECTOR - USE VENDOR NUMBERING SYSTEM AS
- SPECIFIED)
-
-
- 16 bit Wide SCSI-3 "P" (Primary) Connector pinout (single-ended)
- -------------------- --------------------
- | SCSI | HIGH DEN | | SCSI | HIGH DEN |
- | SIGNAL | 68 PIN | | SIGNAL | 68 PIN |
- -------------------- --------------------
- | GND | 1 | | -DB(12)| 35 |
- | GND | 2 | | -DB(13)| 36 |
- | GND | 3 | | -DB(14)| 37 |
- | GND | 4 | | -DB(15)| 38 |
- | GND | 5 | | -DB(P1)| 39 |
- | GND | 6 | | -DB(0) | 40 |
- | GND | 7 | | -DB(1) | 41 |
- | GND | 8 | | -DB(2) | 42 |
- | GND | 9 | | -DB(3) | 43 |
- | GND | 10 | | -DB(4) | 44 |
- | GND | 11 | | -DB(5) | 45 |
- | GND | 12 | | -DB(6) | 46 |
- | GND | 13 | | -DB(7) | 47 |
- | GND | 14 | | -DB(P) | 48 |
- | GND | 15 | | GND | 49 |
- | GND | 16 | | GND | 50 |
- |TERMPWR | 17 | |TERMPWR | 51 |
- |TERMPWR | 18 | |TERMPWR | 52 |
- | RSRVD | 19 | | RSRVD | 53 |
- | GND | 20 | | GND | 54 |
- | GND | 21 | | -ATN | 55 |
- | GND | 22 | | GND | 56 |
- | GND | 23 | | BSY | 57 |
- | GND | 24 | | -ACK | 58 |
- | GND | 25 | | -RST | 59 |
- | GND | 26 | | -MSG | 60 |
- | GND | 27 | | -SEL | 61 |
- | GND | 28 | | -C/D | 62 |
- | GND | 29 | | -REQ | 63 |
- | GND | 30 | | -I/O | 64 |
- | GND | 31 | | -DB(8) | 65 |
- | GND | 32 | | -DB(9) | 66 |
- | GND | 33 | | -DB(10)| 67 |
- | GND | 34 | | -DB(11)| 68 |
- --------------------- ---------------------
- ____________________________
- | _______________________ |
- | 1\ - - - - - - - - - - /34 |
- | 35\- - - - - - - - - -/68 |
- | ------------------- |
- ----------------------------
- "WIDE SCSI-3 P"
- male
-
- ---------------------------------------------------------------------
- ------
-
- IBM's "Not really SCSI" connectors: [Editor(GF)]
-
- Note that this connector is NON-COMPLIANT WITH ANY SCSI STANDARD!
-
- 60 pin Burndy connector as used on IBM RS/6000 systems:
-
- Pin Signal Pin Signal
- --- ------ --- -----
- 1 Gnd 31 Gnd
- 2 -DB(0) 32 -ATN
- 3 Gnd 33 Gnd
- 4 -DB(1) 34 Gnd
- 5 Gnd 35 Gnd
- 6 -DB(2) 36 -BSY
- 7 Gnd 37 Gnd
- 8 -DB(3) 38 -ACK
- 9 Gnd 39 Gnd
- 10 -DB(4) 40 -RST
- 11 Gnd 41 Gnd
- 12 -DB(5) 42 -MSG
- 13 Gnd 43 Gnd
- 14 -DB(6) 44 -SEL
- 15 Gnd 45 Gnd
- 16 -DB(7) 46 -C/D
- 17 Gnd 47 Gnd
- 18 -DB(P) 48 -REQ
- 19 Gnd 49 Gnd
- 20 Gnd 50 -I/O
- 21 Gnd 51 Gnd
- 22 Gnd 52 Reserved
- 23 Gnd 53 Reserved
- 24 Gnd 54 Reserved
- 25 N/C 55 Reserved
- 26 TERMPWR 56 Reserved
- 27 Gnd 57 Reserved
- 28 Gnd 58 Reserved
- 29 Gnd 59 Reserved
- 30 Gnd 60 Reserved
-
- Table of Contents
- ====
- ANSWER From: Gary Field (gfield@zk3.dec.com)
-
- Macintosh Plus SCSI Connector Pinouts
-
- Note that this connector is NON COMPLIANT WITH ANY SCSI STANDARD!
- The grounding is insufficient and does not allow for proper twisted-
- pair
- transmission line implementation. It is recommended that a short
- adapter cable
- be used to convert to the more common Centronics style 50 pin
- connection,
- rather than extend the 25 pin connection any further than necessary.
- The Macintosh Plus used a NCR 5380 SCSI chip controlled by the
- MC68000
- processor.
- ___________________
- | SCSI DB-25S |
- | SIGNAL pin(s) |
- +------------------+ DB-25S (female)
- | -DB(0) | 8 | _____________________________
- | -DB(1) | 21 | 13\ o o o o o o o o o o o o o /1
- | -DB(2) | 22 | 25\ o o o o o o o o o o o o /14
- | -DB(3) | 10 | ------------------------
- | -DB(4) | 23 | View from rear of computer.
- | -DB(5) | 11 |
- | -DB(6) | 12 |
- | -DB(7) | 13 |
- | -DB(P) | 20 |
- | GND | 7,9,14 |
- | GND |16,18,24 |
- | -ATN | 17 |
- | BSY | 6 |
- | -ACK | 5 |
- | -RST | 4 |
- | -MSG | 2 |
- | -SEL | 19 |
- | -C/D | 15 |
- | -REQ | 1 |
- | -I/O | 3 |
- +------------------+
- Pin 25 is NOT CONNECTED in the Mac Plus implementation. Newer Macs
- connect TERMPWR to pin 25, but are otherwise the same.
-
-
-
-
- Future Domain 25 pin connector pinout
- Used on TMC-830/845 and TMC-850/860/885.
- Note:
- Use the Macintosh pinout above for TMC-850M, TMC-1610M, TMC-1650/1670
- or MCS-600
- ___________________
- | SCSI | DB-25S |
- | SIGNAL| pin(s) |
- +-----------------+ DB-25S (female)
- | -DB(0)| 14 | _____________________________
- | -DB(1)| 2 | 13\ o o o o o o o o o o o o o /1
- | -DB(2)| 15 | 25\ o o o o o o o o o o o o /14
- | -DB(3)| 3 | ------------------------
- | -DB(4)| 16 | View from rear of computer.
- | -DB(5)| 4 |
- | -DB(6)| 17 |
- | -DB(7)| 5 |
- | -DB(P)| 18 |
- | GND |1,6,8,13 |
- | GND |13,19,25 |
- | -ATN | 20 |
- | BSY | 23 |
- | -ACK | 22 |
- | -RST | 10 |
- | -MSG | 21 |
- | -SEL | 7 |
- | -C/D | 11 |
- | -REQ | 24 |
- | -I/O | 12 |
- +-----------------+
- Pin 9 is NOT CONNECTED
-
- Table of Contents
- ====
- QUESTION: What is the difference between SCSI-1 and SCSI-2?
- ANSWER From Dal Allen:
- ====
-
- SCSI-1_versus_SCSI-2
-
- In 1985, when the first SCSI standard was being finalized as an
- American National Standard, the X3T9.2 Task Group was approached by a
- group of manufacturers. The group wanted to increase the mandatory
- requirements of SCSI and to define further features for direct-access
- devices. Rather than delay the SCSI standard, X3T9.2 formed an ad hoc
- group to develop a working paper that was eventually called the
- Common Command Set (CCS). Many products were designed to this working
- paper.
-
- In parallel with the development of the CCS working paper, X3T9.2
- sought permission to begin working on an enhanced SCSI standard, to
- be called SCSI-2. SCSI-2 would include the results of the CCS working
- paper, caching commands, performance enhancement features, and
- whatever else X3T9.2 deemed worthwhile.
- While SCSI-2 was to go beyond the original SCSI standard (now
- referred to as SCSI-1), it was to retain a high degree of
- compatibility with SCSI-1 devices.
-
- How is SCSI-2 different from SCSI-1?
-
- 1. Several options were removed from SCSI-1:
-
- a. Single initiator option was removed.
- b. Non-arbitrating Systems option was removed.
- c. Non-extended sense data option was removed.
- d. Reservation queuing option was removed.
- e. The read-only device command set was replaced by the CD-ROM
- command
- set.
- f. The alternative 1 shielded connector was dropped.
-
-
- 2. There are several new low-level requirements in SCSI-2:
-
- a. Parity must be implemented.
- b. Initiators must provide TERMPWR -- Targets may provide TERMPWR.
- c. The arbitration delay was extended to 2.4 us from 2.2 us.
- d. Message support is now required.
-
-
- 3. Many options significantly enhancing SCSI were added:
-
- a. Wide SCSI (up to 32 bits wide using a second cable)
- b. Fast SCSI (synchronous data transfers of up to 10 Mega-transfers
- per second -- up to 40 MegaBytes per second when combined with wide
- SCSI)
- c. Command queuing (up to 256 commands per initiator on each logical
- unit)
- d. High-density connector alternatives were added for both shielded
- and non- shielded connectors.
- e. Improved termination for single-ended buses (Alternative 2)
- f. Asynchronous event notification
- g. Extended contingent allegiance
- h. Terminate I/O Process messaging for time-critical process
- termination.
-
- 4. New command sets were added to SCSI-2 including:
-
- a. CD-ROM (replaces read-only devices)
- b. Scanner devices
- c. Optical memory devices (provides for write-once, read-only, and
- erasable media)
- d. Medium changer devices
- e. Communications devices
-
-
- 5. All command sets were enhanced:
-
- a. Device Models were added
- b. Extended sense was expanded to add:
- + Additional sense codes
- + Additional sense code qualifiers
- + Field replaceable unit code
- + Sense key specific bytes
-
- c. INQUIRY DATA was expanded to add:
- + An implemented options byte
- + Vendor identification field
- + Product identification field
- + Product revision level field
- + Vital product data (more extensive product reporting)
-
- d. The MODE SELECT and MODE SENSE commands were paged for all device
- types
- e. The following commands were added for all device types:
-
- + CHANGE DEFINITION
- + LOG SELECT
- + LOG SENSE
- + READ BUFFER
- + WRITE BUFFER
-
- f. The COPY command definition was expanded to include information on
- how to handle inexact block sizes and to include an image copy
- option.
- g. The direct-access device command set was enhanced as follows:
-
- + The FORMAT UNIT command provides more control over defect
- management
- + Cache management was added:
- - LOCK/UNLOCK CACHE command
- - PREFETCH command
- - SYNCHRONIZE CACHE command
- - Force unit access bit
- - Disable page out bit
-
- + Several new commands were added:
- - READ DEFECT DATA
- - READ LONG
- - WRITE LONG
- - WRITE SAME
-
- + The sequential-access device command set was enhanced as follows:
-
- - Partitioned media concept was added:
- * LOCATE command
- * READ POSITION command
-
- - Several mode pages were added
- - Buffered mode 2 was added
- - An immediate bit was added to the WRITE FILEMARKS command
-
- + The printer device command set was enhanced as follows:
- - Several mode pages defined:
- * Disconnect/reconnect
- * Parallel printer
- * Serial printer
- * Printer options
-
- + The write-once (optical) device command set was enhanced by:
- - Several new commands were added:
- * MEDIUM SCAN
- * READ UPDATED BLOCK
- * UPDATE BLOCK
-
- - Twelve-byte command descriptor blocks were defined for several
- commands to accommodate larger transfer lengths.
-
- =======================================================
-
- The following article was written by Dal Allan of ENDL in April 1990.
- It was published nine months later in the January 1991 issue of
- "Computer Technology Review". While it appeared in the Tape Storage
- Technology Section of CTR, the article is general in nature and tape-
- specific. In spite of the less than timely publication, most of the
- information is still valid.
-
- It is reprinted here with the permission of the author. If you copy
- this article, please include this notice giving "Computer Technology
- Review" credit for first publication.
-
-
-
- What's New in SCSI-2
-
- Scuzzy is the pronunciation and SCSI (Small Computer System
- Interface) is the acronym, for the best known and most widely used
- ANSI (American National Standards Institute) interface.
-
- Despite use of the term "Small" in its name, everyone has to agree
- that
- Scuzzy is large - in use, in market impact, in influence, and
- unfortunately, in documentation. The standards effort that began with
- a 20-page specification in 1980 has grown to a 600 page extravaganza
- of technical information.
-
- Even before ANSI (American National Standards Institute) published
- the first run of SCSI as a standards document in 1986, ASC
- (Accredited Standards Committee) X3T9.2 was hard at work on SCSI-2.
-
- No technical rationale can be offered as to why SCSI-1 ended and
- SCSI-2
- began, or as to why SCSI-2 ended and SCSI-3 began. The justification
- is much more simple - you have to stop sometime and get a standard
- printed. Popular interfaces never stop evolving, adapting, and
- expanding to meet more uses than originally envisaged.
-
- Interfaces even live far beyond their technological lifespan. SMD
- (Storage Module Drive) has been called technically obsolete for 5
- years but every year there are more megabytes shipped on the SMD
- interface than the year before. This will probably continue for
- another year or so before the high point is reached, and it will at
- least a decade before SMD is considered to be insignificant.
-
- If SCSI enhancements are cut off at an arbitrary point, what
- initiates the decision? Impatience is as good an answer as any. The
- committee and the market get sick of promises that the revision
- process will "end soon," and assert pressure to "do it now."
-
- The SCSI-3 effort is actively under way right now, and the workload
- of the committee seems to be no less than it was a year ago. What is
- pleasant, is that the political pressures have eased.
-
- There is a major difference between the standards for SCSI in 1986
- and SCSI-2 in 1990. The stated goal of compatibility between
- manufacturers had not been achieved in SCSI in 1986 due to a
- proliferation of undocumented "features."
-
- Each implementation was different enough that new software drivers
- had to be written for each device. OEMs defined variations in
- hardware that required custom development programs and unique
- microcode. Out of this diversity arose a cry for commonality that
- turned into CCS (Common Command Set), and became so popular that it
- took on an identity of its own.
- CCS defined the data structures of Mode Select and Mode Sense
- commands,
- defect management on the Format command, and error recovery
- procedures. CCS succeeded because the goals were limited, the
- objectives clear and the time was right.
-
- CCS was the beginning of SCSI-2, but it was only for disks. Tape and
- optical disks suffered from diversity, and so it was that the first
- working group efforts on SCSI-2 were focused on tapes and optical
- disks. However, opening up a new standards effort is like lifting the
- lid on Pandora's Box - it's hard to stay focused on a single task.
- SCSI-2 went far beyond extending and consolidating CCS for multiple
- device types.
-
- SCSI-2 represents three years of creative thought by some of the best
- minds in the business. Many of the new features will be useful only
- in advanced systems; a few will find their way into the average
- user's system. Some may never appear in any useful form and will
- atrophy, as did some original SCSI features like Extended Identify.
-
- Before beginning coverage of "what's new in SCSI-2," it might be well
- to list some of the things that aren't new. The silicon chips
- designed for SCSI are still usable. No new features were introduced
- which obsolete chips. The cause of silicon obsolescence has been
- rapid market shifts in integrating functions to provide higher
- performance.
-
- Similarly, initiators which were designed properly, according to SCSI
- in 1986, will successfully support SCSI-2 peripherals. However, it
- should be pointed out that not all the initiators sold over the last
- few years behaved according to the standard, and they can be "blown
- away "by SCSI-2 targets.
-
- The 1986 standard allows either initiators or targets to begin
- negotiation for synchronous transfers, and requires that both
- initiators and targets properly handle the sequence. A surprisingly
- large percentage of SCSI initiators will fail if the target begins
- negotiation. This has not been as much of a problem to date as it
- will become in the future, and you know as well as I do, that these
- non-compliant initiators are going to blame the SCSI-2 targets for
- being "incompatible."
-
- Quirks in the 1986 standard, like 4 bytes being transferred on
- Request
- Sense, even if the requested length was zero have been corrected in
- SCSI-2. Initiators which relied on this quirk instead of requesting 4
- bytes will get into trouble with a SCSI-2 target.
-
- A sincere effort has been made to ensure that a 1986-compliant
- initiator does not fail or have problems with a SCSI-2 target. If
- problems occur, look for a non-compliant initiator before you blame
- the SCSI-2 standard.
-
- After that little lecture, let us turn to the features you will find
- in
- SCSI-2 which include:
-
- o Wide SCSI: SCSI may now transfer data at bus widths of 16 and 32
- bits.
- Commands, status, messages and arbitration are still 8 bits, and the
- B-Cable has 68 pins for data bits. Cabling was a confusing issue in
- the closing days of SCSI-2, because the first project of SCSI-3 was
- the definition of a 16-bit wide P-Cable which supported 16-bit
- arbitration as well as 16-bit data transfers. Although SCSI-2 does
- not contain a definition of the P-Cable, it is quite possible that
- within the year, the P-Cable will be most popular non-SCSI-2 feature
- on SCSI-2 products. The market responds to what it wants, not the
- arbitrary cutoffs of standards committees.
-
- o Fast SCSI: A 10 MHz transfer rate for SCSI came out of a joint
- effort
- with the IPI (Intelligent Peripheral Interface) committee in ASC
- X3T9.3.
- Fast SCSI achieves 10 Megabytes/second on the A-Cable and with wider
- data paths of 16- and 32-bits can rise to 20 Megabytes/second and
- even 40 Megabytes/second. However, by the time the market starts
- demanding 40 Megabytes/second it is likely that the effort to
- serialize the physical interface for SCSI-3 will attract high-
- performance SCSI users to the Fiber Channel.
- A word of caution. At this time the fast parameters cannot be met by
- the Single Ended electrical class, and is only suitable for
- Differential. One of the goals in SCSI-3 is to identify the
- improvements needed to achieve 10 MHz operation with Single Ended
- components.
-
- o Termination: The Single Ended electrical class depends on very
- tight
- termination tolerances, but the passive 132 ohm termination defined
- in 1986 is mismatched with the cable impedance (typically below 100
- ohms). Although not a problem at low speeds when only a few devices
- are connected, reflections can cause errors when transfer rates
- increase and/or more devices are added. In SCSI-2, an active
- terminator has been defined which lowers termination to 110 ohms and
- is a major boost to system integrity.
-
- o Bus Arbitration, Parity and the Identify Message were options of
- SCSI, but are required in SCSI-2. All but the earliest and most
- primitive SCSI implementations had these features anyway, so SCSI-2
- only legitimizes the de facto market choices. The Identify message
- has been enhanced to allow the target to execute processes, so that
- commands can be issued to the target and not just the LUNs.
-
- o Connectors: The tab and receptacle microconnectors chosen for SCSI-
- 2 are available from several sources. A smaller connector was seen as
- essential for the shrinking form factor of disk drives and other
- peripherals. This selection was one of the most argued over and
- contentious decisions made during SCSI-2 development.
-
- o Rotational Position Locking: A rose by any other name, this feature
- defines synchronized spindles, so than an initiator can manage disk
- targets which have their spindles locked in a known relative position
- to each other.
- Synchronized disks do not all have to be at Index, they can be set to
- an offset in time relative to the master drive. By arraying banks of
- synchronized disks, faster transfer rates can be achieved.
-
- o Contingent Allegiance: This existed in SCSI-1, even though it was
- not
- defined, and is required to prevent the corruption of error sense
- data.
- Targets in the Contingent Allegiance state reject all commands from
- other initiators until the error status is cleared by the initiator
- that received the Check Condition when the error occurred.
-
- Deferred errors were a problem in the original SCSI but were not
- described. A deferred error occurs in buffered systems when the
- target advises Good Status when it accepts written data into a
- buffer. Some time later, if anything goes wrong when the buffer
- contents are being written to the media, you have a deferred error.
-
- o Extended Contingent Allegiance (ECA): This extends the utility of
- the
- Contingent Allegiance state for an indefinite period during which the
- initiator that received the error can perform advanced recovery
- algorithms.
-
- o Asynchronous Event Notification (AEN): This function compensates
- for a deficiency in the original SCSI which did not permit a target
- to advise the initiator of asynchronous events such as a cartridge
- being loaded into a tape drive.
-
- o Mandatory Messages: The list of mandated messages has grown:
-
- +----------------------+--------------------------+------------------
- -+
- | Both | Target | Initiator
- |
- +----------------------+--------------------------+------------------
- -|
- | Identify | Abort | Disconnect
- |
- | | |
- |
- | Message Reject | No Operation | Restore Pointer
- |
- | | |
- |
- | Message Parity Error | Bus Device Reset | Save Data Pointer
- |
- | | |
- |
- | | Initiator Detected Error |
- |
- +----------------------+--------------------------+------------------
- -+
-
- o Optional messages have been added to negotiate wide transfers and
- Tags to support command queueing. A last-minute inclusion in SCSI-2
- was the ability to Terminate I/O and receive the residue information
- in Check Condition status (so that only the incomplete part of the
- command need be re-started by the initiator).
-
- o Command Queueing: In SCSI-1, initiators were limited to one command
- per LUN e.g. a disk drive. Now up to 256 commands can be outstanding
- to one LUN.
- The target is allowed to re-sequence the order of command execution
- to optimize seek motions. Queued commands require Tag messages which
- follow the Identify.
- o Disk Cacheing: Two control bits are used in the CDB (Command
- descriptor Block) to control whether the cache is accessed on a Read
- or Write command, and some commands have been added to control pre-
- fetching and locking of data into the cache. Users do not have to
- change their software to take advantage of cacheing, however, as the
- Mode Select/Mode Sense Cache page allows parameters to be set which
- optimize the algorithms used in the target to maximize cache
- performance. Here is another area in which improvements have already
- been proposed in SCSI-3, and will turn up in SCSI-2 products shipping
- later this year.
-
- o Sense Keys and Sense Codes have been formalized and extended. A
- subscript byte to the Sense Code has been added to provide specifics
- on the type of error being reported. Although of little value to
- error recovery, the additional information about error causes is
- useful to the engineer who has to analyze failures in the field, and
- can be used by host systems as input to prognostic analysis to
- anticipate fault conditions.
-
- o Commands: Many old commands have been reworked and several new
- commands have been added.
-
- o Pages: Some method had to be found to pass parameters between host
- and target, and the technique used is known as pages. The concept was
- introduced in CCS and has been expanded mightily in SCSI-2.
-
- A number of new Common Commands have been added, and the opcode space
- for 10-byte CDBs has been doubled.
-
- o Change Definition allows a SCSI-2 initiator to instruct a SCSI-2
- target to stop executing according to the 1986 standard, and provide
- advanced SCSI-2 features. Most SCSI-2 targets will power on and
- operate according to the 1986 standard (so that there is no risk of
- "disturbing" the installed initiators), and will only begin operating
- in SCSI-2 mode, offering access to the advanced SCSI-2 capabilities,
- after being instructed to do so by the initiator using the Change
- Definition command.
-
- o The Mode Select and Mode Sense pages which describe parameters for
- operation have been greatly expanded, from practically nothing in
- 1986 to hundreds of items in SCSI-2. Whenever you hear of something
- being described as powerful and flexible tool, think complicated.
- Integrators are advised to be judicious in their selection of the
- pages they decide to support.
-
- o The Inquiry command now provides all sorts of interesting data
- about the target and its LUNs. Some of this is fixed by the standard,
- but the main benefit may be in the Vendor Unique data segregated into
- the special designation of Vital Product Data, which can be used by
- integrators as a tool to manage the system environment.
-
- o Select Log and Sense Log have been added so that the initiator can
- gather both historical (e.g. all Check Conditions) and statistical
- (e.g. number of soft errors requiring ECC) data from the target.
-
- o Diagnostic capabilities have been extended on the Read/Write Buffer
- and Read/Write Long commands. The ways in which the target can manage
- bad blocks in the user data space have been defined further and
- regulated to reduce inconsistencies in the 1986 standard. A companion
- capability to Read Defect Data permits the initiator to use a
- standard method to be advised of drive defect lists.
-
- o A new group of 12-byte command blocks has been defined for all
- optical devices to support the large volume sizes and potentially
- large transfer lengths. The Erase command has been added for
- rewritable optical disks so that areas on the media can be pre-erased
- for subsequent recording. Write Once disks need Media Scan, so that
- the user can find blank areas on the media.
-
- o New command sets have been added for Scanners, Medium Changers, and
- CDROMs.
-
- All of this technical detail can get boring, so how about some
- "goodies" in SCSI-2 which benefit the common man and help the
- struggling engineer? First, and probably the best feature in SCSI-2
- is that the document has been alphabetized. No longer do you have to
- embark on a hunt for the Read command because you cannot remember the
- opcode.
-
- In the 1986 standard, everything was in numeric sequence, and the
- only
- engineers who could find things easily were the microprogrammers who
- had memorized all the message and opcode tables. Now, ordinary people
- can find the Read command because it is in alphabetic sequence. This
- reorganization may sound like a small matter but it wasn't, it
- required a considerable amount of effort on the part of the SCSI-2
- editors. It was well worth it.
-
- Another boon is the introduction for each device class of models
- which
- describe the device class characteristics. The tape model was the
- most
- needed, because various tape devices use the same acronym but with
- different meanings or different acronyms for the same meaning.
-
- The SCSI-2 tape model defines the terms used by SCSI-2, and how they
- correspond to the acronyms of the different tapes. For example, on a
- 9-track reel, End of Tape is a warning, and there is sufficient media
- beyond the reflective spot to record more data and a trailer. Not so
- on a 1/4" tape cartridge. End of Tape means out of media and no more
- data can be written. This sort of difference in terms causes
- nightmares for standardization efforts.
-
- So there it is; a summary of what is in SCSI-2. It's not scary,
- although it is daunting to imagine plowing through a 600-page
- document. Time for a commercial here. The "SCSI Bench Reference"
- available from ENDL Publications (408-867-6642), is a compaction of
- the standard. It takes the 10% of SCSI-2 which is constantly
- referenced by any implementor, and puts it in an easy-to-use
- reference format in a small handbook. The author is Jeff Stai, one of
- the earliest engineers to become involved with SCSI implementation,
- and a significant contributor to the development of both the 1986
- standard and SCSI-2.
-
- SCSI-2 is not yet published as a standard, but it will be available
- later this year. Until then, the latest revision can be purchased
- from Global Engineering (800-854-7179).
-
- Biography
-
- Consultant and analyst I. Dal Allan is the founder of ENDL and
- publisher of the ENDL Letter and the "SCSI Bench Reference." A
- pioneer and activist in the development and use of standard
- interfaces, he is Vice Chairman of ASC X3T9.2 (SCSI) and Chairman of
- the SCSI-2 Common Access Method Committee.
-
- Table of Contents
- ====
- QUESTION: What is the difference between SCSI-2 and SCSI-3?
- ANSWER From: excerpts of postings by Jeff Stai and others:
- (Mohit K Goyall - goyall@utdallas.edu),
- (Andrew E. Lowman - lowman@arizona.edu)
- ====
-
- Are SCSI-3 hard drives and/or controllers available yet?
-
- Allegedly, Previous postings have said "I heard that SCSI-3 has been
- standardized," but I haven't seen anything firm about it. I've seen
- controllers advertised by JDR Microdevices and some cheap clones; the
- Quantum "Empire" drives are also advertised as SCSI-3 by some mail
- order vendors. Seagate and IBM call their fastest drives (probably
- comparable in speed to the Quantums, if not faster) "Wide SCSI-2."
- That's a misnomer. See below.
-
- What is the difference between SCSI-3 and Fast & Wide SCSI-2?
-
- Wide SCSI-2 required two cables to do 16 bit wide transfers. SCSI-3
- defined a single cable, single REQ/ACK 16 bit, WIDE transfer. The
- reason you are hearing 16-bit single cable being called SCSI-3 is
- that they CAN. The fact that single cable 16-bit has been around for
- a while just shows you how much the standardization process lags
- behind the real world.
-
- SCSI-3 is really a family of standards. SCSI was broken up from a
- single document into different layers and command sets. This was done
- to allow for different physical transport layers (like fibre channel
- and SSA) to be defined, and to allow for smaller "bite-sized"
- projects that maybe get done a little faster ;-)
-
- The family includes the following members with TLAs:
-
- - SCSI-3 Parallel Interface (SPI): Defines the mechanical, timing,
- phases, and electrical parameters of the parallel cable we all know
- and love. Some of the electrical and cable parameters are
- tightened/improved over SCSI-2.
-
- - SCSI-3 Interlock Protocol (SIP): Defines the messages and how the
- phases are invoked. No real change from SCSI-2, except for some new
- messages.
-
- - SCSI-3 Architectural Model (SAM): In a nutshell, defines a common
- set of functions and services and definitions for how a physical
- transport properly gets commands, data, and status exchanged between
- two devices, complete with error handling and queueing.
-
- - SCSI-3 Primary Commands (SPC): All of the commands executed by any
- and all SCSI devices, like REQUEST SENSE and INQUIRY, etc.
-
- - SCSI-3 Block Commands (SBC): Disk commands.
-
- - SCSI-3 Stream Commands (SBC): Tape commands.
-
- - SCSI-3 Controller Commands (SCC): RAID box commands.
-
- - SCSI-3 Multimedia Commands (MMC): For CDROMS etc.
-
- - SCSI-3 Fibre Channel Protocol (FCP): SCSI commands over gigabit
- Fibre Channel.
-
- - SCSI-3 Serial Bus Protocol (SBP): SCSI commands over IEEE 1394 High
- Speed Serial Bus (Apple's "Firewire").
-
- - SCSI-3 Serial Storage Protocol (SSP): SCSI commands over SSA.
-
- whew.
-
-
- Q: After perusing the latest issue of Computer Shopper, I came away
- with the impression that companies are calling F&W SCSI-2 HD's SCSI-
- 3. Is this an incorrect assumption, or is F&W SCSI-2 known as SCSI-3?
- Is this really mostly marketing hype?
-
- Actually, there is something to that. TECHNICALLY, what is out there
- is often a hybrid: SCSI-3 "SPI" silicon with some other hodgepodge of
- SCSI-3 proposals, all mixed in with SCSI-2 stuff.
-
- An earlier posting said that the Quantum Empire ("SCSI-3") drives
- contain some commands from the SCSI-3 command set, and Adaptec
- suggested a specific setting on its 2940W controller to work properly
- with the drive.
-
- I understand there are some drives with proposed SCSI-3 command
- features. These are mostly in the MODE SELECT and in error codes, as
- I recall. Perhaps someone who knows more about this could elaborate?
-
- Note also that the major players (like DC Drives) don't have any
- "SCSI-3" stuff advertised; only JDR and some cheap clones are
- promoting it.
- Besides, Wide SCSI-2 has yet to really catch on (mostly because only
- a few drives are fast enough to take advantage of it).
-
- There is no "wide SCSI-2" because that would mean two cables. Single
- cable wide SCSI has always been SCSI-3, it just took too d*** long to
- get into a standard! :-)
-
- Table of Contents
- ====
- QUESTION: Is SYNCHRONOUS faster than ASYNCHRONOUS?
- ANSWER From: Gary Field (gfield@zk3.dec.com )
- ====
- Yes, the asynchronous transfer option waits for each byte to be
- transferred before it is acknowledged. With synchronous protocol, the
- device sending the data is allowed to get ahead of the device
- receiving the data by a number of bytes (called the offset). The
- offset is negotiated between the initiator and the target some time
- prior to the transfer beginning. The synchronous protocol is
- considerably more efficient and therefore faster than asynchronous.
-
- See also: 1, 2, 3
-
- Table of Contents
- ====
- QUESTION: Is the NCR 53C90 Faster than spec?
- ANSWER From: kstewart@ncr-mpd.FtCollins.NCR.COM (Ken Stewart)
- ====
-
- I've seen a few comments about our 54C90 being faster than spec.
- While I doubt the author was really complaining (I got twice as much
- as I paid for - sure makes me mad ;) I'd like to explain the
- situation. Along the way, I'll also show that asynchronous is faster
- on short cables, while synchronous is faster on long cables. The
- cross-over point occurs somewhere around six feet--assuming that you
- have our 53C90 family devices at both ends of the cable. The reason
- has to do with the propagation delay of the cable; the turn around
- time of the silicon; and the interlocked nature of the asynchronous
- handshake.
-
- 1) We have measured propagation delays from various cables and found
- an average of 1.7 nanoseconds per foot, which is roughly 5.25 ns per
- meter. 2) The turn-around time is the amount of time the SCSI chip
- takes to change an output in response to an input. If REQ is an input
- then ACK is an output. Or if ACK is an input then REQ is an output.
- Typical turn-around time for the 53C90 is 40 nanoseconds.
-
- 3) The asynchronous transfer uses an interlocked handshake where a
- device cannot do the next thing until it receives positive
- acknowledgment that the other device received the last thing.
-
- First REQ goes true /* driven by Target */
- then ACK is permitted to go true /* driven by Initiator */
- then REQ is permitted to go false
- then ACK is permitted to go false
-
- Thus we have four "edges" propagating down the cable plus 4 turn-
- around delays. Asynchronous transfer requires 55 ns setup and no hold
- time (paragraph in 5.1.5.1 in SCSI-1 or SCSI-2) which gives an upper
- speed limit around 18 MB/s. A detailed analysis (assuming 53C90
- family) shows that the setup time subtracts out. This is mostly
- because we are running at one-third the max rate, but also because
- setup for the next byte can begin anytime after ACK is received true
- or REQ is received false, depending on who is receiving. You can
- either take my word for it or draw the waveforms yourself. Thus, the
- asynchronous transfer reduces to:
-
- (4 * 1.7 * 1) + (4 * 40ns) = 167 ns /* 1 foot cable */
- = 6 MB/s
-
- (4 * 5.25 * 6) + (4 * 40ns) = 286 ns /* 6 meter cable */
- = 3.5 MB/s
-
- (4 * 5.25 * 25) + (4 * 40ns) = 685 ns /* 25 meter cable */
- = 1.5 MB/s
-
- note: cables longer than 6 meters require external differential
- transceivers which add delay and degrade the performance even more
- than indicated here.
-
- Our simulations say that under very best conditions (fast silicon,
- low temperature, high voltage, zero length cable) we can expect more
- than 8 MB/s asynchronously. In the lab, I routinely measure 5 MB/s on
- 8 foot cables. So, if you were writing the data manual for this, how
- would YOU spec it?
-
- The framers of the SCSI spec threw in synchronous mode to boost the
- performance on long cables. In synchronous mode, the sending device
- is permitted to send the next byte without receiving acknowledgment
- that the receiver actually received the last byte. Kind of a ship and
- pray method.
- The acknowledgment is required to come back sometime, but we just
- don't have to wait for it (handwave the offset stuff and the ending
- boundary conditions). In this mode any external transceivers add a
- time shift, but not a delay. So if you negotiate for 5 MB/s, you get
- 5MB/s regardless how long the cable is and regardless whether you are
- single-ended or differential. But you can't go faster than 5.5 MB/s,
- except in SCSI-2.
- Synchronous mode does have a hold time (unlike asynch) but again,
- setup and hold times subtract out. In SCSI-1 synchronous mode, the
- speed limit comes from the combined ASSERTION PERIOD + NEGATION
- PERIOD which is 90ns + 90ns = 180ns = 5.5 MB/s. Our 53C90 family
- doesn't quite hit the max, but we do guarentee 5.0 MB/s. In SCSI-2,
- anything above 5.0 MB/s is considered to be FAST. Here the maximum
- transfer rate is explicitly limited to 100 ns or 10MB/s; you don't
- have to read between the lines to deduce it.
-
- Interesting tid-bit: given a SCSI-2 FAST period of 100 ns and a cable
- delay of 131 ns on a 25 meter cable, you can actually stack 1.31
- bytes in the 8-bit cable. In FAST and WIDE SCSI you can stack 5.24
- bytes in this copper FIFO.
- Hummm...
-
-
- Table of Contents
- ====
- QUESTION: What are the jumpers on my Conner drive?
- ANSWER From: ekrieger@quasar.hacktic.nl (Eric Krieger)
- Embellishment from: Henrik Stahl (f92-hst@nada.kth.se)
- ====
- QUICK INSTALLATION GUIDE
-
- SCSI
- Most SCSI host adapters are compatible with Conner drives. Software
- drivers and installation instructions are provided with the host
- adapter.
-
- The drives are shipped with SCSI ID set to 7. To select a different
- ID refer to the following:
-
- Table A Table B
- ID E-1 E-2 E-3 ID E2 E3 E4
- 0 out out out 0 out out out
- 1 in out out 1 in out out
- 2 out in out 2 out in out
- 3 in in out 3 in in out
- 4 out out in 4 out out in
- 5 in out in 5 in out in
- 6 out in in 6 out in in
- 7 in in in 7 in in in
-
- Parity is always ENABLED on the CP3200,CP30060,CP30080,CP30100,
- CP 30200, CP 3500, CP 3360, CP 30540 and CP 31370.
-
- For the CP 340, jumper E-1 to disable parity.
-
- All other models, jumper E-4 to disable parity.
-
- SCSI drive parameters:
-
- Model Hds Cyl Sec Table LED
- CP2020 2 642 32 A n/a
- CP340 4 788 26 B 1
- CP3020 2 622 33 A 1
- CP3040 2 1026 40 A 1
- CP3180 6 832 33 A 1
- CP3100 8 776 33 A 1
- CP30060 2 1524 39 A 2
- CP30080 4 1053 39 A 2
- CP30100 4 1522 39 A 2
- CP30200 4 2119 49 A 2
- CP3200 8 1366 38 A 2
- CP3360 8 1806 49 A 2
- CP3540 12 1806 49 A 2
- CP 30080E 2 1806 46 AA C/E
- CP 30170E 4 1806 46 AA C/E
- CP 30540 6 2249 59-89 AA B
- CP 31370 14 2094 59-95 AA B
-
- LED 1 LED 2
- J-4 Pin 1 = + J-1 Pin 3 = +
- Pin 2 = - Pin 4 = -
-
- On the CP 31370, jumper E5 enables termination. Default is
- termination on. It may be the same jumper for other models.
-
-
-
- Table of Contents
- ====
- QUESTION: What are the jumpers for my Wangtek 5150 drive?
- ANSWER From: Terry Kennedy (terry@spcvxa.spc.edu)
- ====
-
- First, the disclaimer: This is not an official representation of
- Wangtek or of my employer. This is info I've discovered by reading
- publicly available reference material. When changing jumpers, always
- observe proper anti-static precautions and be sure you have the
- current configuration written down so you have a known starting
- point.
-
- Ok. Here's the complete scoop on Wangtek 5150ES drives:
-
- The current part number for a "generic" 5150ES is:
-
- 33685-201 (black faceplate)
- 33685-202 (beige faceplate)
-
- These are referred to as the "ACA version" of the drive.
-
- There are _many_ other part numbers for 5150ES drives. If you have
- one that isn't one of the above, it doesn't mean you have an old or
- an out of rev drive, it just means it's a special version created for
- a distributor or OEM, or with different default jumper settings.
-
- You can order the Wangtek 5150ES OEM Manual from Wangtek. It is part
- number 63045-001 Revision D.
- There are 5 possible logic boards. Here are the jumper options for
- each:
-
- Logic assembly #33678
- ---------------------
-
- (J10)
- 0 - SCSI unit LSB
- 1 - SCSI unit
- 2 - SCSI unit MSB
- K - not documented
-
- J32 - Diagnostic test connector, default is not installed
- E1, F1 - SCSI termination power. E1 in = power from drive and to
- cable,
- E1 out - power from cable. F1 = terminator power fuse, 1.5A
- FB.
- Default is IN.
- E2 - Chassis ground. E2 in jumpers logic to chassis ground. E2 out
- isolates through a .33 uFD capacitor. Default is IN.
- E5 - Master oscillator enable. Test only. Must be IN.
- E20 - Factory test. Must be OUT.
- RP1, RP2, RP3 - SIP terminators. Default is IN, remove for no
- termination.
-
- Logic assembly #30559
- ---------------------
-
- HDR1 - Factory testing. Setting depends on drive. Don't touch.
- HDR2 - Factory testing. Defaults are pins 15-16, 17-18, 19-20. Don't
- touch.
- HDR3 pin 1 - A-B enables buffered mode. B-C disables. Can be
- overridden by SCSI Mode Select.
- HDR3 pin 2, 3 - Default data format. Set to B-C for a 5150ES.
- HDR3 pin 4 - parity enable. A-B enables, B-C disables.
-
- (J10)
- 0 - SCSI unit LSB
- 1 - SCSI unit
- 2 - SCSI unit MSB
- K - not documented
-
- E1 - SCSI termination power. E1 in = power from drive and to cable,
- E1 out - power from cable.
- E2 - Chassis ground. E2 in jumpers logic to chassis ground. E2 out
- isolates through a .33 uFD capacitor. Default is IN.
- E3 - Master oscillator enable. Test only. Must be IN.
- E4 - Write test mode. Test only. Must be OUT.
- E5 - Write oscillator enable. Test only. Must be IN.
- E6 - Disable HDR2. Test only. Must be IN.
- E7 - Microcontroller clock select. In for a 5150ES.
- E8 - Write precomp select. Set on a per-drive basis. Don't touch.
- E9 - RAM size. Don't touch.
- E10 - Erase frequency. Don't touch.
- RP2, RP3 - DIP and SIP terminators. Default is IN, remove for no
- termination.
-
- Logic assembly #30600
- ---------------------
-
- HDR1 - Factory testing. Setting depends on drive. Don't touch.
- HDR2 - Write precomp select. Set on a per-drive basis. Don't touch.
- HDR3 pin 1, 2, 3 - SCSI device address. 1 is LSB, 3 is MSB. A-B=1, B-
- C=0
- HDR3 pin 4 - Parity enable. IA-B is enabled.
- HDR3 pin 5, 6 - Default data format. B-C for a 5150ES.
- HDR3 pin 7 - Buffered mode select. A-B is enabled.
- HDR3 pin 8 - Reserved. Must be OUT.
- HDR4 - Write frequency select. Don't touch.
- E1 - SCSI termination power. E1 in = power from drive and to cable,
- E1 out - power from cable.
- E2 - Chassis ground. E2 in jumpers logic to chassis ground. E2 out
- isolates through a .33 uFD capacitor. Default is IN.
- E3 - Hard/soft reset. IN enables hard reset.
- E4 - Write precomp select. Don't touch.
- E5 - Clock speed. Don't touch.
- E6 - Tape hole test. Don't touch.
-
- Logic assembly #30552
- ---------------------
-
- HDR1 - Factory testing. Setting depends on drive. Don't touch.
- HDR2 - Write precomp select. Set on a per-drive basis. Don't touch.
- HDR3 pin 1, 2, 3 - SCSI device address. 1 is LSB, 3 is MSB. [Note -
- HDR3
- pins 1-3 are duplicated at another location on the
- board]
- HDR3 pin 4 - Parity enable. IN is enabled.
- HDR3 pin 5, 6, 7, 8 - Default data format. 5,5 B-C, 7-8 A-B for a
- 5150ES.
- HDR4 - Write frequency select. Don't touch.
- E1 - SCSI termination power. E1 in = power from drive and to cable,
- E1 out - power from cable.
- E2 - Chassis ground. E2 in jumpers logic to chassis ground. E2 out
- isolates through a .33 uFD capacitor. Default is IN.
- E3 - Hard/soft reset. IN enables hard reset.
- E4 - Write precomp select. Don't touch.
- E5 - Clock speed. Don't touch.
- E6 - Tape hole test. Don't touch.
-
- Logic assembly #30427
- ---------------------
-
- HDR1 - Factory testing. Setting depends on drive. Don't touch.
- HDR2 - Write precomp select. Set on a per-drive basis. Don't touch.
- HDR3 pin 1, 2, 3 - SCSI device address. 1 is LSB, 3 is MSB. A-B=1, B-
- C=0
- HDR3 pin 4 - Parity enable. IA-B is enabled.
- HDR3 pin 5, 6, 7, 8 - Default data format. 5,5 B-C, 7-8 A-B for a
- 5150ES.
- E1, E3 - Factory test. Must be IN.
- E2 - SCSI termination power. E2 in = power from drive and to cable,
- E2 out - power from cable.
- E4 - Chassis ground. E4 in jumpers logic to chassis ground. E4 out
- isolates through a .33 uFD capacitor. Default is IN.
-
- Firmware - There are many flavors of firmware. I have seen the
- following parts:
-
- 24115-xxx
- 24144-xxx
- 21158-xxx
-
- the -xxx suffix changes as the firmware is updated. According to the
- folks I spoke to at Wangtek, the standard firmware is the 21158. The
- latest version as of this writing is 21158-007. All of these will
- work with the Adaptec and GTAK.
-
- The firmware options (as returned by a SCSI Identify) are on the end
- of the product string, which is "WANGTEK 5150ES SCSI ES41C560 AFD QFA
- STD" for the 21158-007 firmware. The 3-letter codes have the
- following meaning:
-
- AFD - Automatic Format Detection - the drive will recognize the
- format (such as QIC-24, QIC-120, or QIC-150) that the tape was
- written in.
-
- QFA - Quick File Access - the ability to rapidly locate a tape block,
- and to implement the "position to block" and "report block" SCSI
- commands. This is compatible with the Tandberg implementation.
-
- STD - Standard feature set.
-
-
- Table of Contents
- ====
- QUESTION: How do I configure my HP DDS DAT tape drive?
- ANSWER From: Alan Strassberg (alan@lmsc.lockheed.com)
- ====
-
- The HP DDS Configuration Guide (postscript) can be found at:
- http://www.impediment.com/hp/hp_2.ps
-
- Table of Contents
- ====
- QUESTION: What is ASPI?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- ASPI stands for Advanced SCSI Programming Interface. It was developed
- by Adaptec. It is a calling convention and set of commands that can
- be used to send SCSI commands via any SCSI host adapter that supports
- it. It is strictly for use with Intel x86 machines running MSDOS,
- Windows( 3.1x, 95 or NT), Netware, or OS/2. There is no UNIX version.
- The error reporting and recovery mechanisms are much more limited
- than in CAM, but ASPI gained much wider acceptance because it was
- available earlier.
-
- Table of Contents
- ====
- QUESTION: What is CAM?
- ANSWER From: ctjones@bnr.ca (Clifton Jones)
- ====
-
- CAM stands for Common Access Method.
- It is an ANSI standard to make it easier to program SCSI applications
- by encapsulating the SCSI functions into a standardized calling
- convention.
- [Editor(GF): It is similar to ASPI but much more elaborate and
- complete].
-
- ANSWER From: landis@sugs.tware.com (Hale Landis)
- ====
- You can get the CAM spec(s) from the SCSI BBS
-
- Table of Contents
- ====
- QUESTION: What is FPT (Termination)?
- ANSWER From: jvincent@bnr.ca (John Vincent)
- ====
- FPT stands for Forced Perfect Termination. FPT is actually really
- simple, I wish I had thought of it. What it does is use diode clamps
- to eliminate over and undershoot. The "trick" is that instead of
- clamping to +5 and GND they clamp to the output of two regulated
- voltages. This allows the clamping diodes to turn on earlier and is
- therefore better at eliminating overshoot and undershoot. The block
- diagram for a FPTed signal is below. The resistor value is probably
- in the 110 Ohm range. The actual output voltages of the regulators
- may not be exaclty as I have shown them but ideally they are matched
- to the diode characteristics so that conduction occurs when the
- signal voltage is greater than 3.0 V or less than 0.2 V.
-
-
- +-----------*--- TERMPWR
- | |
- ____|___ |
- | | |
- | Vreg 1 |---------------------------------* 2.8 V
- |________| | |
- | | |
- ----- | |
- --- | \
- - | / term resistor
- | \ (110 Ohms)
- | /
- ____|___ |
- | | |
- | Vreg 2 |-*--------* 2.4 V |
- |________| | | |
- | --+-- |
- | / \ |
- +------+ /___\ |
- | | |
- | | | terminated
- | *----------*------------- signal
- | |
- | |
- | --+--
- | / \
- | /___\ Both diodes are fast silicon
- | | switching diodes (.6 V drop)
- ___|____ |
- | | |
- | Vreg 3 |----------* 0.8 Volts
- |________|
-
- The diagram shows the circuit for terminating one signal. In a
- complete FPT there would be 36 diodes and 18 110 Ohm resistors plus
- the regulator chips.
- Using the values shown, transients would be clamped at 0.2V and 3.0V.
-
- [Editor(GF)]:
- Some errors in the above diagram were corrected as suggested by
- Wietze van Winden (wietze@ittpub.nl)
-
- Table of Contents
- ====
- QUESTION: What is Active Termination?
- ANSWER From: eric@telebit.com (Eric Smith)
- and brent@auspex.com (Brent R. Largent)
- ====
-
- An active terminator actually has one or more voltage regulators to
- produce the termination voltage, rather than using resistor voltage
- dividers.
-
- This is a passive terminator:
-
-
- TERMPWR ------/\/\/\/------+------/\/\/\/----- GND
- |
- |
- SCSI signal
-
- Notice that the termination voltage varies with the voltage on the
- TERMPWR line. One voltage divider (two resistors) is used for each
- SCSI signal.
-
-
- An active terminator looks more like this (supply filter caps
- omitted):
-
- 2.85 Volt Regulator
- +-----------+ +2.85V 110 Ohms
- TERMPWR -----| in out |------+------/\/\/\/-------SCSI signal
- | gnd | |
- +-----------+ |
- | +------/\/\/\/-------SCSI signal
- | |
- GND ---------------+ |
- +------/\/\/\/-------SCSI signal
- |
- etc.
-
- Assuming that the TERMPWR voltage doesn't drop below the desired
- termination voltage (plus the regulator's minimum drop), the SCSI
- signals will always be terminated to the correct voltage level.
- Several vendors have started making SCSI active terminator chips,
- which contain the regulator and the resistors including Dallas
- Semiconductor, Unitrode Integrated Circuits and Motorola.
- [Editor(GF): Another nice feature of activer termination is that it
- can be disabled by a single jumper instead of needing to unplug
- resistor arrays.]
-
- Table of Contents
- ====
- QUESTION: Why Is Active Termination Better?
- ANSWER brent@auspex.com (Brent R. Largent)
- ====
-
- Typical passive terminators (resistors) allow signals to fluctuate
- directly in relation to the TERM Power Voltage. Usually terminating
- resistors will suffice over short distances, like 2-3 feet, but for
- longer distances active termination is a real advantage.
-
- Active termination provide the following advantages:
- - Helps reduce noise.
- - A logic bit can be used to effectively disconnect the termination.
- - Regulated termination voltage.
- - SCSI-2 spec. recommends active termination on both ends of the scsi
- bus.
- - Improved resistance tolerances (from 1% to about 3%)
-
- [Editor(GF):
- - Reduces current drawn from TERMPWR line.
-
- In FPT form:
- - Provides signal overshoot/undershoot clamping on all signal lines.
- ]
-
-
- Table of Contents
- ====
- QUESTION: How can I tell whether an unmarked terminator is active or
- passive?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- If you have an Ohm-meter of one kind or another, measure the
- resistance from the TERMPWR pin to an adjacent GROUND pin. Reverse
- the probes and take another reading.
-
- If the reading is about 30.5 Ohms, with the probes both ways, you
- have a passive single-ended terminator.
-
- If the reading is about 45 Ohms, with the probes both ways, you have
- a passive differential terminator.
-
- Active terminators should read much higher and give very different
- readings with the probes interchanged.
-
-
- Table of Contents
- ====
- QUESTION: Where can I buy terminators ?
- ANSWER From: Rodney Brown (RBrown@cocam.com.au)
- Info taken from Usenet postings by:
- John Zatler (JPZ@Popmail.mcs.com)
- Steve Schreppler (schrep@oasys.dt.navy.mil)
- Dave Nadler (nadler@ug.eds.com)
- ====
-
- DataMate / Methode
-
- Methode Electronics, Inc.
- dataMate Division
- 7444 West Wilson Avenue
- Chicago, IL 60656
- (708) 867-9600
- (800) 323-6858
- (708) 867-3149 FAX
- WWW: http://www.methode.com/datamate/dmhome.htm
-
- Brief description of terminators available.
-
- Passive, Active, SLICK (Elaboration of FPT)) in:
- Centronics 50 pin (SCSI-1) DM8[05]0-09-[0RS]
- Male 3 row D-Sub (Old Sun) DM950-??-?
- Male 50 position .050" Centres (SCSI-2 HD) DM20[05]0-02-[0RS]
- Male 68 position .050" Centres (SCSI-3 P cable) DM2050-02-68[RS]
- Male & Female for ribbon cables DM1050-02-[0RS] (M),
- DM650-06-[0RS] (F)
- Male/Female for pass through between device and ribbon cable DM550-
- 06-[0RS]
-
-
- Newark Electronics stocks the DataMate product line.
-
- Newark Electronics (International orders)
- 4801 N. Ravenswood Ave. 500 N. Pulaski St.
- Chicago IL 60640-4496 Chicago IL 60624-1019
- (312)-784-5100, (FAX (312)-638-7652, TLX 6718690 NEWARK U).
- WWW: http://www.newark.com/
-
-
- Selectronix Ltd
- Minerva House, Calleva Park,
- Aldermaston, Reading, RG7 8NE, UK
- Tel: +44 (0)118 9817387
- Fax: +44 (0)118 9817608
- WWW: http://www.selectronix.co.uk/
-
- Cables To Go
- http://www.cablestogo.com/
-
-
- Technical Cable Concepts Inc.
- http://www/techcable.com/
-
-
- Table of Contents
- ====
- QUESTION: What is Plug and Play SCSI?
- ANSWER From: leefi@microsoft.com (Lee Fisher) (Updated Dec 7 1993)
- ====
-
- Plug and Play is the name of a technology that lets PC hardware and
- attached devices work together automatically. A user can simply
- attach a new device ("plug it in") and begin working ("begin
- playing"). This should be possible even while the computer is
- running, without restarting it.
- Plug and Play technology is implemented in hardware, in operating
- systems such as Microsoft Windows, and in supporting software such as
- drivers and BIOS.
-
- With Plug and Play technology, users can easily add new capabilities
- to their PCs, such as sound or fax, without having to concern
- themselves with technical details or encountering problems. For users
- of mobile PCs (who are frequently changing their configurations with
- docking stations, intermittent network connections, etc.) Plug and
- Play technology will easily manage their changing hardware
- configuration. For all users, Plug and Play will reduce the time
- wasted on technical problems and increase their productivity and
- satisfaction with PCs.
-
- The Plug and Play technology is defined in a series of specifications
- covering the major component pieces. There are specifications for
- BIOS, ISA cards, PCI, SCSI, IDE CD-ROM, PCMCIA, drivers, and
- Microchannel. In a nutshell, each hardware device must be able to be
- uniquely identified, it must state the services it provides and the
- resources which it requires, it must identify the driver which
- supports it, and finally it must allow software to configure it.
-
- The first Plug and Play compliant products are available now, as are
- development kits for drivers and hardware. Twenty different Plug and
- Play products were shown at Comdex in November 1993.
-
- Specifications:
- The Plug and Play specifications are now available via anonymous ftp
- at ftp.microsoft.com in the \drg\plug-and-play subdirectory. The
- files are compressed in .zip format, and are in Microsoft Word
- format.)
-
- Plug and Play ISA files (.\pnpisa\*)
-
- errata.zip Clarifications and corrections to pnpisa.doc
- isolat.zip MS-DOS testing tool to isloate ISA PnP hardware
- pnpdos.zip Plug and Play device driver interface specification
- pnpisa.zip Hardware spec for PnP ISA enhancement
- vhdlzi.zip Hardware spec for PnP ISA enhancement
-
- Plug and Play SCSI files (.\scsi_ide\*):
-
- pnpscsi.zip Plug and Play SCSI specification proposal
- scam.zip SCAM (SCSI Comnfigured Auto-Magically) specification
-
- Plug and Play BIOS files (.\bios\*):
-
- apmv11.zip Advanced Power management spec v.1
- vios.zip Plug and Play BIOS spec
- escd1.zip Spec for optional method of storing config info for PnP
- BIOS
-
- PlayList@Microsoft.COM alias:
-
- There is an alias, PlayList@Microsoft.COM, which you can email and
- get on a Microsoft mailing list related to Plug and Play, where the
- Hardware Vendor Relations Group (HVRG) will mail out new
- specifications, announcements, information on workshops, Windows
- Hardwware Engineering Conference (WinHEC), etc...
-
- Compuserve PlugPlay forum:
-
- There is a forum on Compuserve, GO PLUGPLAY. This forum is the method
- for support, discussions and dialogs about Plug and Play. In
- addition, the forum's library contains all of the current
- specification.
-
- Intel Plug and Play kits:
-
- If you are interested in Intel's two Plug and Play kits, either "Plug
- and Play Kit for MS-DOS and Windows" or "Plug and Play BIOS
- Enhancements Kit", FAX your name and company information to Intel at
- 1.503.696.1307, and Intel will send you the information.
-
-
- Table of Contents
- ====
- QUESTION: Where can I get drivers (ASPI and other) for the WD7000
- FASST2 host adapter?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
-
- Western Digital stopped producing WD7000 FASST2 cards some
- time in 1990. Future Domain bought the rights to produce them. Future
- Domain was later bought out by Adaptec and the boards are no longer
- produced. Columbia Data Products Inc. of Altamonte Springs, Florida
- still provides driver support for the card. Their SST IV driver
- package provides support for many types of SCSI devices including
- disks, tapes, and CDROM. Also included in this package is an ASPI
- manager driver (equivalent to the Adaptec ASPI4DOS.SYS). I have
- personally tested this ASPI manager and it works with GNU tar w/ASPI
- and the Corel CDROM driver, so most other ASPI stuff should work too.
- Versions of SSTASPI.SYS prior to Oct 1993 do NOT work with the above
- mentioned programs so be sure to check the file date. There are other
- useful programs in the package as well. For instance I find the
- TAPEUTIL program very handy for duplicating tapes. The price of this
- package is $99 or $85 as an upgrade of a previous version.
- A pre-requisite to run this software is that the adapter card must
- have a BIOS ROM version of 3.36 or newer. I don't think cards
- manufactured before 1989 or so are compatible.
-
- Columbia Data Products Inc.
- 1070 B Rainer Dr
- Altamonte Springs, FL 32714 (407) 869-6700 (main number)
- (407) 862-4725 (fax)
- http://www.cdp.com (Columbia home web page)
- cdp@cdp.com (Columbia e-mail)
-
-
- [Update to above information 1/20/97][Editor(GF)]
-
- From: "Alan L. Welsh" <snapback@ix.netcom.com>
- Subject: Western Digital 7000-Fasst SCSI Cards and CDP's SST software
- Alan L. Welsh, President
- Columbia Data Products, Inc.
-
- We don't usually recommend that users purchase the upgrade for the
- 7000 software today. Development has ceased, Windows 95 is not
- supported except in DOS mode, and today I would rather recommend a
- popular currently manufactured Local-bus SCSI board and not an ISA
- 7000 board. However, there are still some companies that we do
- support that have standardized on 7000s and need to keep them in
- service for years to come. So please buy the software, sell the
- board, use it as-is, or buy a new board.
- http://www.cdp.com cdp@cdp.com
-
- ---------------------
-
- HISTORY OF THE WD-7000 SCSI HOST ADAPTER AND COLUMBIA DATA PRODUCTS,
- INC.
-
- Starting in early 1987, Western Digital (WD) manufactured virtually
- all of the 100,000+ 7000 SCSI boards, except for a few hundred that
- were made by Future Domain. The first few thousand, known as 7000-ASC
- boards went out with no software and only a ROMBIOS that was actually
- written by John Sponger of WD. In the summer of 1987, Columbia Data
- Products (CDP) completed and shipped its first ROMBIOS for the card
- that enabled it to boot and operate in DOS. At that same time, CDP
- also completed a DOS ram-resident driver, so that DOS would recognize
- and operate the card without the slowness of the ROMBIOS, a DASD
- driver so that DOS could access additional drive letters, and to
- break the (then) 32 meg barrier, and partitioning software to perform
- the FDISK function for SCSI.
-
- It was CDP's goal at that time to develop and provide SCSI software
- that would enable: any SCSI host adapter, to run any SCSI peripheral,
- on any operating system, in any PC-based bus. Since at that time WD
- had 80% of the hard drive controller market, CDP chose WD as the most
- logical choice to strategically market with, and so CDP supported
- their cards almost exclusively. During that following year, CDP
- continued to develop the software for the 7000 host adapters,
- enabling it to run faster than any other board of its time, including
- Adaptec's new 1540, whose hardware was actually faster.
-
- In the fall of 1988, CDP exclusively licensed its SCSI software
- suite,
- called SST to WD. The WD 7000-asc SCSI host adapter was renamed 7000-
- FASST. WD was the first OEM to ship software with all SCSI boards
- distributed as part of the package. CDP's SST software was well
- received, even though SCSI was still a relatively small market. CDP
- was paid a royalty for each card shipped and CDP provided complete
- software support and limited hardware support throughout the world.
-
- By 1991 CDP had developed support for all SCSI peripherals known, all
- PC operating systems such as Unix, Xenix, Windows, Dos, Netware, and
- even AIX, although never officially released, and a SCSI toolkit
- utility package.
- All of the 7000-FASST's shipped had multiboot capability that allowed
- all of these operating systems to simultaneously coexist on a single
- hard drive so that one OS can be selectively booted each session.
-
- CDP's exclusive was ending with WD, and CDP was porting the software
- to 25 of the most popular SCSI host adapters. Unfortunately, most of
- software had to be re-architected and rewritten to embrace not only
- all the new adapters but also the new SCSI software standards such as
- CAM, LADDR, ASPI, INT-4b, as well as CDP's own standard since 1987,
- SDLP. During the next few years WD was losing a considerable amount
- of money and sold many of their product lines, which included selling
- the SCSI board business to Future Domain. Future Domain did very
- little sales of the 7000 as they had competing product lines and
- didn't understand the value of a bus mastering SCSI board. (Bus
- mastering gives the card the ability to move data to and from the
- card and system memory directly without the CPU's involvement, making
- it as fast as the peripherals driving it, even on an old slow 80286!)
- The bus mastering 1542 product line from Adaptec is still being
- produced today, very popular, and is based on the same basic design
- as the 7000. From a pricing standpoint, the prices for this class of
- product has declined less than 50% in ten years. This is only amazing
- if you compare the price of 1MB of memory at $300 in 1987 to that of
- today.
-
- CDP has continued to develop and support for the 7000-FASST
- continuously, even though the board hasn't been manufactured for
- quite a number of years.
- Our last major revision of our SST-IV software was done in late 1993,
- although there have been some minor revisions since then. To enable
- CDP to continue to develop software and support the board, CDP has
- been selling upgrades to the large installed user base for years.
- Without this revenue, development and support would have ceased long
- ago. There are no plans to continue development at this time, as SCSI
- is moving from the ISA bus to Local Bus. Although Window-95
- development and support was considered, the potential upgrade
- business wouldn't have covered the cost of development.
-
- In 1994 CDP entered the server backup software market, shipping the
- first version of Snapback in March of that year. Many of our
- customers for years had been begging us to write our own backup
- software and were complaining that "restoring" their servers
- sometimes took days with the current backup products. For SCSI
- software development purposes only, CDP had been backing up and
- restoring hard drives containing multiple operating systems for
- years. CDP adapted and then rewrote this software in this first
- release to provide the ability to backup and restore any hard drive
- that contained any operating system, from DOS. CDP later wrote a
- device driver in Netware, that could make the backup tape look, act
- and perform like a hard drive from a Netware workstation. This
- enabled direct file retrieval and use through Netware from the backup
- tape, making it appear to a workstation to be just another drive
- letter. Since all the directories and FATs are cached, the tape is
- almost as fast as a hard drive. Another feature, resize, allows a
- Netware server's hard drive to be replaced with a larger one in an
- hour instead of a day's labor.
-
- At fall COMDEX 1996, CDP released its latest version, Snapback Live!
- That backs up a live image of a Netware file server's hard drive,
- capturing all open files in the process, without impacting system
- performance. Watch your Computer magazine for Snapback reviews in
- 1997, as well as a version for NT. Innovating backup software has now
- become CDP's new life--from an innovative SCSI software company.
-
- For more information, contact us at:
- http://www.cdp.com OR cdp@cdp.com
-
- Table of Contents
- ====
- QUESTION: What if I have a SCSI drive larger than a gigabyte
- (1024MB)?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- The IBM PC/AT BIOS Int 13h disk interface was specified in about 1986
- when a large disk drive was about 60 MB. IBM decided that disks
- wouldn't have more than 1024 cylinders and only allocated 10 bits for
- the CYL parameter to the INT 13h interface. By 1989, this was already
- a problem. When vendors began to support SCSI drives under INT 13h,
- they needed to come up with a translation algorithm between the CYL,
- HEAD, SECT parameters of INT 13h and the linear block numbers used by
- SCSI devices. Various vendors chose to map the two such that each INT
- 13h "cylinder" contained 1 MB.
- In other words they emulated a drive with 32 heads and 63 sectors per
- track.
- At the time, large drives were at about 300 MB, so this worked OK.
- Once drives larger than 1024 MB arrived, a problem developed. They
- couldn't provide cylinder values greater than 1023! Changing
- algorithms became necessary.
- This is painful since any disk formatted with the old algorithm can't
- be read using the new algorithm.
- By the way, different vendors chose different mappings, so drives
- formatted with one adapter can't necessarily be moved to a different
- one.
- Adaptec's newer adapters (e.g. the 154xC and the 154xCF) provide a
- BIOS control to select the old algorithm or the new one, and they
- also provide BIOS PROMs for the 154xB that will use the new
- algorithm.
- There is an absolute limit of 16 M sectors which means 8 GB assuming
- 512 byte sectors. Also DOS only allows 2 GB per partition.
- The day when this presents another problem is not too far away
- (1995?)
- Hopefully, we'll all be running more sophisticated O/Ses that bypass
- this limitation by then.
-
- Table of Contents
- ====
- QUESTION: My SCSI bus works, but is not reliable. What should I look
- at?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- If you still have problems after you're sure that you have all the ID
- and termination and cable issues resolved, it's time to dig a little
- deeper.
- If you get your SCSI bus to the point where it basically works, but
- it isn't reliable I have found that the gremlin can be the TERMPWR
- voltage.
-
- With your system fully powered up, and both terminators attached,
- measure the TERMPWR voltage at the far end of your bus. It needs to
- be between 4.25 and 5.25 Volts. Many vendors start with the system's
- +5 VDC and add a regular silicon rectifier diode and fuse in series.
- Silicon rectifiers have an inherent voltage drop of .6 to 1.0 Volts
- depending on the current through them.
- Schottky barrier rectifiers are much better for this application. I
- always use a 1N5817 myself. If the diode on the host adapter is a
- 1N400x type, change it to a 1N5817. If you add up the drop across the
- diode and the fuse and 15 feet of ribbon cable and the connector
- contact resistances, many times you'll find yourself below 4.0 Volts.
- When using passive terminators, this can shift the signal threshold
- and decrease the signal to noise ratio on the bus.
- If you aren't able to get relief with these methods, sometimes you
- can solve the problem by having several devices supply TERMPWR to the
- bus.
-
- Sometimes the voltage is high enough, but there is too much noise on
- the TERMPWR line. This can cause really strange problems! If you can
- see more than about 200 mV of noise on TERMPWR, add a .1 uF and 10 uF
- capacitor from TERMPWR to one of the adjacent GROUND lines. You need
- to have the bus as active as you can get it when measuring the noise.
- I have actually seen over 1 Volt of noise in some severe cases.
-
- Another way you can help to solve TERMPWR problems is to use active
- terminators. These don't draw as much current from the TERMPWR source
- and they also have a built in regulator which can operate on lower
- voltage than the standard passive terminators. The regulator also
- tends to reduce the noise.
-
-
- Table of Contents
- ====
- QUESTION: Where can I find information about programming using the
- ASPI
- interface from DOS and Windows?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
-
- The Adaptec BBS has some documents about ASPI. They also have a WWW
- server.
- See the FAQ Question "How can I contact Adaptec?" for phone numbers
- and URL information etc.
-
- ftp://ftp.adaptec.com/pub/BBS/adaptec/aspi*
-
- Dr Dobb's Journal March 1994 issue pg 154, has an article called "The
- Advanced SCSI Programming Interface" by Brian Sawert. Example code in
- C and x86 assembly language is included. The code can be obtained via
- anonymous ftp from: ftp.mv.com: /pub/ddj/1994.03/aspi.zip.
-
- Table of Contents
- ====
- QUESTION: How do I replace Macintosh internal HD and terminate the
- SCSI chain properly?
- Answer From: Jie Yuan PhD (Jie.Yuan@UC.Edu)
- ====
- The factory installed Macintosh internal HD should be terminated.
- Make sure the terminator/resitor-package is installed in the drive
- before using it. Most vendors will install the terminator for you if
- you tell them it is for use in Macintosh as the system disk.
- Manufacturers usually have toll free numbers for SCSI termination,
- ID, and such. If you don't already have the terminator, they may send
- you one for free. BTW, Macintosh SCSI chain starts at the system disk
- (ID=0), and ends at the control board (ID=7). ID numbers from 1-6
- should be used for any other devices on the chain.
-
- Table of Contents
- ====
- QUESTION: Will attaching a SCSI-1 device to my SCSI-2 bus hurt its
- performance?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Attaching a SCSI-1 device to a system with a SCSI-2 host adapter and
- several SCSI-2 devices already attached will not hurt over-all
- performance significantly unless it doesn't handle
- disconnect/reconnect well. This assumes that the host adapter keeps
- track of protocol options separately for each target device. Some
- people have the idea that attaching a SCSI-1 device to a SCSI-2 bus
- will cause the entire bus to run at SCSI-1 speeds. This is not true.
-
- Table of Contents
- ====
- QUESTION: Can I connect a SCSI-3 disk to my SCSI-1 host adapter?
- Can I connect a SCSI-2 CDROM to a SCSI-3 host adapter?
- Can I connect a Narrow SCSI2 disk to a WIDE SCSI3 host
- adapter?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Questions of this nature really cannot be answered in a useful way.
- There are so many aspects and options to each of the SCSI standards,
- you need to be much more specific about what devices and adapters
- you're interested in connecting. Most of the time the best thing to
- do is just try it! Most combinations will work, but if you're
- considering a purchase and looking for a guarantee from "The Net",
- forget it.
-
- The issue is further complicated by the fact that vendors like to
- latch onto the latest acronyms before they even know what's involved.
- For example SCSI3 is not approved yet, but vendors are already saying
- their devices are SCSI3 compatible. Since there is no standards
- compliance testing organization, they can pretty much say what they
- want.
-
- If you buy a high end host adapter (probably called SCSI3 :-) ) from
- a reputable vendor, and it has enough control over the various
- options (like synch xfer rate 5,10,20 xfers/s and the ability to
- disable WIDE or FAST/Ultra negotiation), and you carefully think out
- what devices you connect to it (all WIDE devices nearest the host
- adapter end of the bus etc.), and you are careful to properly
- terminate not only both ends, but both halves (upper byte and lower
- byte) of the bus, and none of the older devices you might already
- have (like a Panasonic CDROM) do anything stupid (like not handle the
- WIDE negotiation message without hanging) then it will all work fine.
- :-)
-
- Even though a host adapter may be called SCSI3 doesn't mean it can
- enable or disable each optional feature, yet this is vital for
- supporting older devices.
-
- To make matters worse, you won't know which older devices do some of
- the stupid things unless you know someone who's been bitten already.
- Your best bet is to look for good deals on name brand devices and
- adapters and before you buy, ask in comp.periphs.scsi whether anyone
- has tried the combination you're considering. It's also important to
- buy from a well known vendor with reasonable return policies.
-
- If you're looking at buying a Vendorxyz spiffydisk which claims to be
- SCSI-3 compatible and you have a Seagate ST-01 host adapter and you
- want to know if anyone else has tried this combination, then that's
- exactly what you should ask.
-
- In general, most SCSI devices and adapters made less than 4 years
- apart will probably work together, but without specific information
- about exactly which devices there's no assurance of it. There's also
- the potential for poor performance even if it does work.
-
-
- Table of Contents
- ====
- QUESTION: Can I connect a WIDE device to my narrow SCSI host adapter?
- QUESTION: Can I connect a narrow device to my WIDE SCSI host adapter?
- ANSWER FROM: Gary Field (gfield@zk3.dec.com)
- ====
-
- Yes, you just need an appropriate adapter. Most WIDE devices use the
- 68 pin "P" connector so you need a 68 pin to 50 pin adapter. You do
- need to make sure that both the upper byte and lower byte of the bus
- will be properly terminated though. Some adapters provide a place for
- terminators, others do not. If the wiring adapter is placed right at
- the SCSI host adapter, you can usually configure the host adapter's
- on-board terminators to only terminate the high byte. You need to be
- clear on what type of connectors are present where you want to do the
- conversion. You also need to plan your bus so that all the WIDE
- devices will be at one end and all the narrow devices will be at the
- other end. Certain host adapters with auto-termination make the
- assumption that when the low byte is terminated the high byte is
- also. When using WIDE/narrow adapters this assumption is not valid.
- If for some reason you attach a WIDE device to a narrow bus, you must
- be sure to disable WIDE negotiation in the host adapter BIOS or the
- device will hang when it is accessed.
- One further caveat is that if narrow devices are attached to a WIDE
- adapter, the adapter's ID must be between 0 and 7 because narrow
- devices would not be able to see it if the ID was any higher than 7.
-
- WIDE to NARROW adapters are available from:
-
- Technical Cable Concepts
- 1790 E. McFadden Ave.
- Unit 103/104
- Santa Ana, CA 92705
- TEL: (714) 835-1081
- FAX: (714) 835-1595
- http://www.techcable.com/
-
- MegaHaus
- 2201 Pine Drive
- Dickinson, TX 77539
- E-Mail megahaus@phoenix.net
- Order Line 800-786-1157
- Fax Line (281)534-6580
- Main Line (281)534-3919
- http://www.megahaus.com/
-
- Dalco Electronics
- P.O. Box 550
- 275 South Pioneer Blvd.
- Springboro, OH 45066-1180
- http://www.dalco.com/
-
- Warning: I am told that some 68 pin to 50 adapters have TERMPWR wired
- incorrectly such that some of the 4 TERMPWR lines on the 68 pin
- connector get connected to the pin opposite TERMPWR on the 50 pin
- side. This pin was originally a GROUND signal (in SCSI1 spec.) and
- was later changed to OPEN to prevent shorting TERMPWR if the
- connector was reversed.
- Also, some of these TERMPWR lines might be connected to the RESERVED
- pins adjacent to TERMPWR. Some drives interpreted RESERVED to mean
- "OK to connect to GROUND" and therefore attaching one of these will
- also short out TERMPWR.
- The proper wiring is for all 4 TERMPWR lines on the 68 pin side to
- connect to the one TERMPWR line on the 50 pin side and leave the
- RESERVED lines not connected.
-
-
- Table of Contents
- ====
- QUESTION: How does device ID numbering work with WIDE vs NARROW
- devices?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
-
- Narrow SCSI devices can only use IDs 0 through 7. WIDE SCSI devices
- on a SCSI-3 system with 68 pin P cables, can use IDs 0 through 15. It
- is generally wise to reserve 0-7 for narrow devices though. SCSI-2
- only specified the use of IDs 0-7 even for WIDE devices, but SCSI-3
- allows 0-15 for WIDE devices. All devices on one bus must have unique
- Ids of course.
- The arbitration priorities are as follows:
- highest
- ID 7
- ...
- ID 0
- ID 15
- ...
- ID 8
- ID 23
- ...
- ID 16
- ID 31
- ...
- ID 24
- lowest
-
- A WIDE device that is set to ID 10 knows not to respond to selection
- for ID 2 because the parity bit P1 (for bits 8-15) will not be set by
- the initiator. During a selection of ID 10, the P parity bit (for
- bits 0-7) will not be set by the initiator, but the P1 bit will be.
- To use both WIDE and narrow devices on the same bus, the host adapter
- must be set to ID 7 (or less) so that the narrow devices can talk to
- it.
-
- Table of Contents
- ====
- QUESTION: What is spindle-sync and why would I want it?
- ANSWER From: Roger J. Hamlett (Roger@ttelmah.demon.co.uk)
- ====
-
- It fundamentally affects just one aspect of performance, the
- 'latency'. With a single drive, if you are waiting for a sector to
- 'arrive' round a track, you have (on average) to wait for
- approximately one half the rotational time of the drive for it to
- arrive. So you might arrive at the track just as the sector has gone
- by, and have to wait one whole rotation at the worse, or the sector
- might arrive just as you want it, and latency would be zero. This
- average time, is the minimum latency achievable. There are two
- methods of reducing this time. The first is to increase the
- rotational rate of the drive. This is why for certain types of
- application a 7200RPM drive, will still outperform a 5400RPM drive
- that has the same data rate off the drive. The other method is to
- have multiple copies of the required data on unsynchronized drives,
- and take whichever copy arrives first. This can be done with mirrored
- drives, and gives a small improvement in the latency time. However
- the 'down side' of multiple drives comes when we have to wait for all
- the data parts to arrive. So (for instance) on a striped array, if
- the drives are synchronized, the latency will remain the same as for
- the single drives with both data 'parts' arriving together. However,
- if the drives are unsynchronized, the 'total' latency goes up, to 33%
- 'worse' than the single drive, as we now have to wait for both parts
- to arrive. Similar 'extensions' take place with other RAID
- configurations, unless the drives are synchronized. Basically, in
- RAID arrays, the drives should be synchronized, _unless_ the total
- required data can be assembled from a small fraction of the drives.
- RAID 1, and RAID 10, are the commonest configurations where
- synchronization is not advised.
-
- Table of Contents
- ====
- QUESTION: What are the general steps I need to do to install a SCSI
- disk to be used with Windows?
- ANSWER From: Roberto Waltman (rwaltman@bellatlantic.net)
- ====
-
- This description assumes an Adaptec host adapter, but other types
- should involve about the same procedure.
-
- Let me start from scratch and describe one by one all necessary
- steps:
- Prepare a bootable MS-DOS floppy (SYS A: ) containing, in addition to
- the system files, the FDISK.EXE and FORMAT.COM programs. (Preferably
- the ones that came with your Win95 distribution). Make sure there
- isn't anything in the AUTOEXEC.BAT or CONFIG.SYS files that could
- make trouble later. Better still, delete these two files. Do not
- insert the floppy yet.
- Reset your computer and enter the BIOS setup, (not the SCSI setup)
- and make sure that the "disk type" is set to 'none' or 'not
- installed' or something similar. Verify that the boot sequence is A:
- first.
- Exit and reset
-
- (If your host adapter is new, you can probably skip the next step,
- but if you want to avoid mysteries later, itÆs not a bad idea to do
- it.)
- Enter the SCSI setup (CTRL-A) and go to the setup menu. Press F6 to
- restore all the default settings.
- Exit and reset
-
- Enter the SCSI setup (CTRL-A) and go to the utilities menu. Make sure
- you see your disk in the list of devices, and the name and model look
- OK.
- Select the proper disk and run the "Format"
- Choose Verify media" to build your confidence that the drive is
- really working right.
- If these two steps work ok, your disk and controller are fine and
- they are communicating correctly. If not, you have a hardware
- problem. (check cables?, terminators?, TERMPWR?, disk itself?)
- (It is not necessary to wait for the verify function to finish,
- although it is a good idea to do it with a new disk.)
- Exit and reset.
-
- Boot from the floppy this time. While the system is coming up, a
- message on the screen will show up saying something like "<your disk
- model> C: 80H BIOS Installed." This means that the SCSI controller
- recognized the disk, and since there is not an IDE C: disk, it
- installed the necessary BIOS functions to use the SCSI disk as 'C:'
- It does NOT mean that the C: drive is ready for DOS/Windows. If you
- don't get that message check that the SCSI disk is installed as
- device ID 0. (With newer host adapters you can use Ids other than 0)
- After getting the A:> prompt, run FDISK. Create a primary DOS
- partition. (2 GB max except for Win 95 OSR2 w/FAT32). Make that
- partition active.
- Exit and reboot from the floppy.
-
- At this point you already have a C: drive, but you can not use it
- because it has no file system. (Typing DIR C:, for example, will
- produce the error message 'Invalid media type', different from the
- 'Invalid drive specification' you got before)
- To make a file system run FORMAT C: /S /U. The /S tells the format
- program to copy the system files to C: at the end of the formatting.
- This will make C a bootable disk. (Assuming the partition was made
- active above )
- When the FORMAT program ends, you should be able to switch to C:, do
- a DIR, etc.
-
- Remove the floppy, reset and (hopefully) reboot from the hard disk.
-
- Notes for mixing IDE and SCSI disks on the same system?
- The IDE disk must be defined properly in the BIOS setup (disk type=
- number or autodetect instead of "not installed as above").
- If you will only boot from the IDE disk, the SCSI disk doesn't need
- to be made bootable. (Some modern BIOSes let you choose to boot from
- SCSI even if an IDE disk is installed)
- The BIOS in the SCSI controller will install a maximum of two disks.
- If you have an IDE disk installed, the SCSI BIOS will still install
- the (first) SCSI disk. If you have 2 IDE disks
- You'll have to install SCSI drivers in the boot disk to access the
- SCSI disk or disks. If you have a system with 4 SCSI disks (no IDE)
- the controller's BIOS will install only the first two;
- Again you'll have to install drivers to access the rest, etc.
-
- Table of Contents
- ====
- QUESTION: My SCSI CDROM only works when Windows 95 is installed. How
- can I get Windows 95 installed? Is this a catch 22?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Since Windows 95 generally is installed from CDROM media, obviously
- your system needs to be able to read a CDROM before you can install
- Windows 95.
- This is done by creating a boot diskette containing the necessary
- drivers to allow the SCSI adapter to talk to the CDROM drive.
- For a system with an Adaptec 2940 host adapter this means:
- Make an MSDOS bootable floppy.
- Add the drivers youÆll need (as mentioned below) and the MSCDEX
- program to the floppy.
- Create two files on the floppy as follows:
- CONFIG.SYS:
- LASTDRIVE=I
- DEVICE=ASPI8DOS.SYS /D
- DEVICE=ASPICD.SYS /D:MSCD000
-
- AUTOEXEC.BAT:
- MSCDEX /D:MSCD000 /M:12 /L:J
-
- If you have a different host adapter, find out from your manual what
- the equivalent driver names are for your card.
-
- Once you get the system booted, select drive J (the CDROM), and run
- SETUP.EXE
-
- Table of Contents
- ====
- QUESTION: Under Windows 95 OSR2 I can only see the first 8 GB of my 9
- GB disk. WhatÆs going on?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- The retail version of Windows 95 is limited to 2 GB per disk by the
- use of the FAT16 filesystem. Since youÆre getting more than 2 GB, you
- must be using a FAT32 filesystem.
- Using FAT32 with drives larger than 8 GB requires a host adapter that
- supports the "INT 13 extensions". If your host adapter was built
- before about 1996, you may not have this feature. For example Adaptec
- 2940W
- Host adapters did not support this. Even the early 2940UW didnÆt have
- it. As of BIOS ver. 1.2x the support is present. Check with your host
- adapter manufacturer for an updated BIOS.
-
- Table of Contents
- ====
- QUESTION: Are there any storage related reasons to upgrade to Windows
- 95 OSR2?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Yes, Microsoft has made a few enhancements:
- FAT-32 filesystem
- which has the following features:
- Default cluster size of 4k bytes for drives up to 8 GB.
- Supports drives up to 2 Terrabytes (2048 GB).
- Will only install on drives > 512 MB.
- Can use the "backup" copy of the FAT if needed.
- Is ONLY accessible from Windows 95 OSR2. (Not supported by Windows
- NT)
- CDFS (ISO-9660) enhancements.
- Drive Power Management.
- 120 MB floptical support.
- The mini-port driver for the Adaptec 2940xx
- (\windows\system\iosubsys\aic78xx.mpd) is updated. In the retail
- version of Windows 95 there are problems with the Microsoft supplied
- driver. If the above mentioned file is older than April '96, you need
- a new one. The updated driver is also available from
- http://www.adaptec.com/.
-
- For more information, see the Win95 OSR2 FAQ.
-
- Table of Contents
- ====
- QUESTION: I changed the host adapter in my system and now my disk
- doesnÆt work. Why?
- ANSWER From: Gary Field (gfield@zk3.dec.com)
- ====
- Each manufacturer chooses their own algorithm for converting
- cylinder, head and sector to a SCSI logical block number. If you run
- into this, you need to back up your system to tape or CD-R using the
- old host adapter, switch host adapters, low level format the disk
- (using the host adapter's BIOS), re-partition (using FDISK), and re-
- initialize the filesystem (using FORMAT), then restore all the data
- from the backup media.
- Not as easy as you expected huh?
-
- Table of Contents
- ====
- End.
- ====
-
- _
-
- --
- --/* Gary Field - WA1GRC, Digital Equipment Corp., 110 Spit Brook Rd
- M/S ZKO3-3/T79, Nashua, NH 03062-2698, phone: (603) 884-2543
- email: gfield@zk3.dec.com http://fieldnet.ne.mediaone.net/ TZ=EST5EDT
- My wife says I don't listen to her; At least I think that's what she said. */
-