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1995-10-04
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_ _ _
/ / (_)
_\ \ \
(_)_/_/ SGATFMT4.EXE v4.0 - Seagate Format drive utility.
Copyright 1992-1995 Seagate Technology, Inc. All rights reserved.
Introduction
------------
! READ THIS ENTIRE DOCUMENT BEFORE USING THIS PROGRAM. THIS PROGRAM
! IS DESTRUCTIVE TO USER DATA. SEVERAL SPECIFIC WARNINGS AND
! RECOMMENDATIONS ARE GIVEN THAT MAY PERTAIN TO YOUR DISC DRIVE.
SGATFMT4 (Seagate Format) is a lo-level formatting utility designed
for AT 286/386/486 systems, only. (If the program is run on an XT,
most likely a stack overflow error message will display.)
SGATFMT4 is designed and LIMITED to work with the following Seagate
disc drive interfaces: ST412 (both MFM and RLL), ESDI (with controller
bios disabled), and ATA/IDE (with certain limitations). SCSI
interface disc drives are not supported. (See the section "ABOUT
DRIVES NOT LISTED")
SGATFMT4 does not use the system BIOS to access the drive, but instead
uses the AT register command set. This means that it is not necessary
to pre-set a CMOS drive-type prior to the lo-level format. The CMOS
drive type will become mandatory, however, prior to partitioning and
the DOS hi-level format (see the section below on SETTING CMOS DRIVE
TYPES).
SGATFMT4 only works if the controller/host adapter is set to the
primary hard drive port addresses of 1F0-1F7. (This is the common port
address used on most controllers.)
SGATFMT4 checks to see if a Seagate ST21/22 M or R controller is
installed with its on-board controller bios enabled. If this
condition exists, SGATFMT4 will exit and issue an appropriate debug
command to initiate the controller's built in lo-level format.
====================================================================
There are three basic steps to preparing a hard disc drive for use in
a computer system:
1. Lo-level format (MFM, RLL, ESDI, and some SCSI)
2. Partitioning with the operating system software.
3. Hi-level formatting with the operating system software.
SGATFMT4 addresses step number 1. In addition to preparing a hard
disc drive for use, SGATFMT4 also has practical use as a diagnostic
utility to test drive functionality.
==========================================================
The opening first screen is used to determine which of two drives is
to be selected for the lo-level format. If only one drive exists in
the system then select drive 0 by pressing 0, followed by the Enter
key:
█▀▀▀██ █▀▀▀██ █▀▀▀██▀▀▀█▀▀▀▀ █▀▀▀▀▀▀ █▀▀█▀▀██▀▀▀█▀▀▀▀ Ver. 4.0
█▄▄▄▄▄ ██ █▄▄▄██ ██ █▄▄▄▄ ██ ██ ██ ██
██ ██ ▀██ ██ ██ ██ ██ ██ ██ ██
█▄▄▄██ █▄▄▄██ ██ ██ ██ ██ ██ ██ ██ (tm)
┌─────────────────────────────────┐
│ ───────────────█─────────────── │
│ ───────────────█─────────────── │
│ ───────────────█─────────────── │
▄▄▄┴▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄█▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄┴▄▄▄
█ █
┌──────────────────────────────> Drive 0 █
│ █ ▄ █
│ █ █
│ ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
│
└────────────< (Look for your choice to show up here)
Please select physical hard drive 0 or 1 press <ret> to select
After the drive selection is made, the next step is to identify the
model:
┌─────────────────────────────────┐
│ ───────────────█─────────────── │
│ ───────────────█─────────────── │
│ ───────────────█─────────────── │
▄▄▄┴▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄█▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄┴▄▄▄
█ █
█ Drive 0 █
█ ▄ ┌─────> ST124 █
█ │ █
▀▀▀▀▀▀▀▀▀│▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
│
└──< (Look for your choice here)
Please select a Seagate drive model, press <ret> to select
U =prev D =next HOME =first END =last PGUP =U10 PGDN =D10
If your model drive is not listed, go to the end of the models list
and select CUSTOM. This is a user defined drive input geometry that
will require values for Cylinders, Heads, and Sectors per Track.
Once the model has been identified and the Enter key is pressed, the
Main Menu appears:
╔═════ FORMAT OPTIONS ═══════╗
║ ║
║ 1. Format Drive ║
* ║ 2. Enter Defects ║
║ 3. Verify Drive ║
║ 4. Format/Verify Drive ║
║ 5. Choose Another Drive ║
* ║ 6. Optimize Interleave ║
║ ║
╚════════════════════════════╝
(* Menu option not available when ATA/IDE ZBR drive selected.)
1. Format Drive : This is the main working part of SGATFMT4.
When this selection is made a warning appears, advising that ALL DATA
WILL BE ERASED. This is very serious business! If you haven't backed
up your data, then STOP! Under no circumstances is Seagate
responsible for lost data.
For MFM, RLL and ESDI interface drives: You will be asked to select
or test for the proper interleave value. Next you will be queried for
head and cylinder skew values (see INTERLEAVE and SKEWING sections
below). A format on a disc drive is very controller dependent and
usually means that the format performed by one controller cannot be
utilized by another.
2. Enter Defects : For MFM, RLL and ESDI interface drives:
Affixed to the top of every Seagate MFM and RLL disc drive, is a list
of micro-defects that were found to exist at the time of manufacture.
Seagate's original list should contain less than 1 defect per
formatted megabyte and defect-free on the first two cylinders. The
micro-defects that have been detected are generally of two types: hard
and soft. A hard defect is usually a surface problem and a soft
defect is usually a magnetic anomaly of some kind. Soft defects are
discovered at the factory with very sophisticated test equipment,
while hard defects can be discovered with conventional software like
SGATFMT4.
The typical defect label on the top of the drive is usually made up of
three columns: Cyl Hd BFI and might look like this:
67 0 7814
68 0 7815
69 0 7816
175 2 3316 and so on.
The column heading "BFI" stands for Bytes From Index. It may also be
listed as "BCAI" which stands for Byte Count After Index, and is the
same thing. The Index pulse is usually generated by a Hall sensor
that is embedded in the spindle motor or else it is encoded on servo
tracks. This index pulse is considered the absolute point of
reference for the BFI or BCAI count. With BFI, an individual sector
can be located and locked out as opposed to locking out the entire
track. If a defect is entered in SGATFMT4 without a BFI (a BFI of 0),
then the entire track is locked out . Once all of the defects are
entered, the specific areas will be marked as bad upon exiting the
module. (see ANATOMY OF A SECTOR below)
3. Verify Drive : This module should still be proceeded by a
complete backup before use. Verify is available to search out hard
defects. If the micro-defect list has been removed from the drive or
the suspicion of a new defect arises, then Verify can be run. It will
report to the screen, and optionally to the printer, a cylinder, head,
and sector reference. Unfortunately, a specific BFI cannot be
reported. Therefore, if a subsequent lo-level format is performed, a
BFI of 0 will need to be entered.
Verify will ask if you want to do destructive pattern testing. If
answered "No", the program operates in a read-only mode. If answered
"Yes", you can choose up to nine different patterns that are used in
write-read mode. (Note: a high capacity drive may take several hours
to complete if all nine patterns are selected.)
4. Format/Verify Drive : This function combines the Format
and Verify procedures into a single operation. This step does
provide, however, for marking out "discovered" defects at the sector
level instead of whole tracks at the time of formatting.
5. Choose Another Drive : If two physical drives are
installed, this allows for switching between them. Be ABSOLUTELY SURE
you are aware of which drive is selected. The next saddest person in
the world is the one who formats the wrong drive!
6. Optimize INTERLEAVE: For MFM, RLL and ESDI interface
drives: The interleave value for a hard disc drive determines how many
times a disc needs to spin in order to read a single track of data.
The typical disc drive usually spins at 3,600 rpm (or 60 times per
second). On a MFM disc drive with 17 sectors per track, the
Read/Write heads, drive circuitry, controller and CPU are required to
process all 17 sectors in 1/60th of a second. SGATFMT4 can test the
system and report which interleave yields the fastest data transfer
rate for your system (this is a data destructive test, be sure to back
up 100% of your data before running the interleave tests). The best
interleave possible is 1 to 1, meaning 1 revolution to read 1 track of
data. Interleaves are always whole numbers, so the next best
interleave is 2 to 1.
1 to 1:
1- 2- 3- 4- 5- 6- 7- 8- 9-10-11-12-13-14-15-16-17
(with sector 17 looping around to meet sector 1)
2 to 1:
1-10- 2-11- 3-12- 4-13- 5-14- 6-15- 7-16- 8-17- 9
(with sector 9 looping around to meet sector 1)
It takes a little getting used to looking at this, but the most
important fact to keep in mind is that the operating system reads the
sectors in sequential order and will read on until the next sector in
sequence appears. On the 2 to 1 interleave example the disc will need
to spin two times in order to read all 17 sectors. Most of today's
modern controllers are designed for a 1 to 1 interleave. Some early
16-bit controllers for 286's were only 3 to 1 or 2 to 1.
An interesting problem happens if a 1 to 1 interleave is selected on a
controller not designed for this speed: The Disc ends up performing
like it has a 17 to 1 interleave! The reason for this is quite
simple. If sector 2 immediately follows sector 1, and the controller
isn't ready to read sector 2, then the disc needs to spin all the way
around again in order to pick up on sector 2. This extra spin would
be needed for all 17 of the sectors.
==========================================================
SKEWING
--------
By way of an analogy, the function of the modern disc drive has been
described like this: "Today's new generation of disc drives achieve
the engineering equivalent of a Boeing 747 flying at MACH 4 just two
meters above the ground, counting each blade of grass as it flies
over. The read/write head floats at 12 millionths of an inch above
the surface of the disc which is turning at 3,600 revolutions per
minute. Read/write heads position precisely over information tracks
which are 800 millionths of an inch apart and the data is
electronically recorded at 20,000 bits per inch."
Skewing is best understood by first looking at the layout of a
non-skewed disc drive. With the limitations of a two-dimensional
drawing, a single circular MFM track has 17 sectors and would look
like this:
1- 2- 3- 4- 5- 6- 7- 8- 9-10-11-12-13-14-15-16-17
(with sector 17 looping around to meet sector 1)
The platters within the drive are spinning at a very high rate
(usually 3,600 rpm), so one sector is passing beneath the R/W head
once every 980 millionths of a second! This is obviously a very small
timing window. When the entire track is processed, it is time to move
to the next head (on another surface) in the cylinder. For example: a
drive with two heads reads track 1 head 1, track 1 head 2, then
repositions the heads over the next track and reads track2 head 1,
track 2 head 2, and so on. The time it takes to switch between heads
is extremely fast since it is an electronic change. The time it takes
to reposition over another cylinder, however, takes significantly
longer since it requires a mechanical movement that is an order of
magnitude slower.
Looking again at the 17 sectors, if we stack two heads we see:
head 1 : 1- 2- 3- 4- 5- 6- 7- ...... -17
head 2 : 1- 2- 3- 4- 5- 6- 7- ...... -17
We would expect sector 1 on head 2 to immediately follow sector 17 on
head 1. Unfortunately, this doesn't happen because it TAKES TIME (or
"overhead") to switch to the new head, and by the time it does, sector
1 has already gone by! Therefore the R/W head waits for the disc to
spin around once for sector 1 to show up again so it can get on with
its job. Effectively, we have wasted one disc revolution that equals
1/60th of a second which could have processed almost an entire track
of 17 sectors. This is the crux of the problem that skewing
addresses: eliminating unnecessary disc revolutions.
The solution is easy; shift the beginning position of sector 1 head 2
enough to compensate for the head switching overhead. That way when
head 1 sector 17 finishes and the head switches, sector 1 head 2 would
be spinning into place. Remembering that tracks are circular, it
would look like this:
head 1 : 1- 2- 3- 4- 5- 6- 7- ...... -15-16-17
head 2 : 16-17- 1- 2- 3- 4- 5- ...... -13-14-15
\--|--/
|
Shifting these two sectors gives us time to allow for
the head switching overhead and is the equivalent to HEAD SKEW = 2.
In normal use, a disc drive switches heads many times more often than
it does switching physical cylinders. The data throughput can rise
dramatically when a head skew is in place. For example, a simple
non-head skewed MFM drive might have a transfer rate of 380kps and the
transfer rate of a drive with a head skew of 2 could rise to around
425kps. (Since we've listed a kind of performance result, here, it is
VERY important to point out that ALL systems/controllers have
different amounts of overhead and processing power, not to mention the
wide range of results from different transfer rate diagnostics.
A formula for calculating a head skew value is as follows (but be sure
to read on):
HEAD SKEW =
[( head switch time * SPT * spindle speed ) / 60,000 ] + 2
Ex: [( <15 µS * 17 * 3600 ) / 60,000 ] + 2 = 2
└────────┬─────────────────────┘
┴
Basically, this evaluates to zero, and the 2 is a typical overhead for
most MFM controllers.
Cylinder skewing is usually a little more drastic. It stands to
reason that since the mechanics of repositioning the head assembly is
going to be significantly slower than an electronic head switch, the
value for a cylinder skew will be larger. Going back to our two head
drive, we might see:
Cyl 1: head 1 : 1- 2- 3- 4- 5- 6- 7- 8- 9-10-11-12-13-14-15-16-17
head 2 : 16-17- 1- 2- 3- 4- 5- 6- 7- 8- 9-10-11-12-13-14-15
Cyl 2: head 1 : 8- 9-10-11-12-13-14-15-16-17- 1- 2- 3- 4- 5- 6- 7
\-----------|-----------/
|
Shifting these eight sectors gives us
time to account for the cylinder switching overhead and is the
equivalent to CYLINDER SKEW = 8.
A formula for calculating a cylinder skew value is as follows:
CYLINDER SKEW =
[( max track to track time * SPT * spindle speed ) / 60,000 ] + OHFactor
Ex: [( 8 msec * 17 * 3600 ) / 60,000 ] + 0 = 8 (ok to round
down on MFM)
Note: OHFactor is an 'overhead factor' that is tied to SPT or sectors
per track. After some casual experimentation, we've figured -
SPT OHFactor
17 0 or 1 (usually MFM drives)
26 - 31 1 or 2 (usually RLL drives)
33 - 52 2 or 3 (usually ESDI drives)
53 - >> 3 or 4 (usually high end ESDI drives)
The "0 or 1" type values are intended to be ambiguous, and are meant
to illustrate that these values are system/controller dependent. The
higher of the two numbers is the most conservative. Generally,
choosing a value a little high is not as bad as choosing a value too
low, thereby causing a wasted disc revolution. Now is a good time to
recall that it is the head skew value that offers the most significant
boost to the transfer rate, while an optimized cylinder skewing helps
only when the heads are repositioned over a different track. If you
use a transfer rate utility to measure performance results, be advised
that many of them just use a single cylinder and don't reflect
cylinder skews.
==========================================================
ABOUT DRIVES NOT LISTED
-----------------------
Some points about lo-level formatting drives not listed above:
In the case of all SCSI drives:
These drives use a controller (properly called a host adapter) that
has an onboard BIOS chip. Coded within this bios chip is a lo-level
format utility (called 'firmware' as opposed to 'software') which can
initiate special SCSI commands. The fact that virtually all SCSI host
adapters have this capability, precludes the need for a stand-alone
software utility like SGATFMT4. Defect management on SCSI drives is
handled at the factory and/or by the drive "on-the-fly" on more
advanced drives, and is transparent to the user. Access to the SCSI
host adapter's lo-level format utility is usually through the DOS'S
DEBUG utility. Typically, you would start DEBUG, and then at the
"hyphen prompt" (DEBUG's user-friendly interface), type "G=C800:5"
without quotes and followed by ENTER (where C800 is the BIOS upper
memory address selected by jumpers on the host adapter).
In the case of ESDI drives:
These drives normally use a controller with an onboard BIOS that has
the lo-level utility. Many ESDI drives have cylinder counts that
exceed the DOS limitation of 1024. The ESDI controller's on-board
bios is required to "translate" these values in order to achieve full
capacity from the drive. Defect management for ESDI drives has been
simplified over that of typical MFM drives. The manufacturer has
placed a small file on the drive which lists the coordinates of the
defects (cylinder, head, and BFI or BCAI) that can be read by the
controller, thereby eliminating the need to enter them by hand. Access
to the ESDI controller's lo-level format utility is usually through
the DOS'S DEBUG utility. Typically, you would start DEBUG, and then
at the "hyphen prompt" (DEBUG's user-friendly interface), type a GO
command, -G=C800:5 (where C800 is the BIOS upper memory address
selected by jumpers on the controller). ESDI drives can be defined
optionally, with the BIOS on the controller card disabled, in a
user-definable or custom CMOS drivetype. SGATFMT4 supports this
bios-disabled condition.
In the case of RLL drives :
These drives also normally use a controller like the ST21/22R
controllers with an onboard BIOS that has the lo-level utility. Defect
management for RLL drives is the same as MFM drives. Defects are
usually listed on a sticker affixed to the top of the drive and need
to be entered manually during the lo-level format. Access to the RLL
controller's lo-level format utility is usually through the DOS'S
DEBUG utility. Typically, you would start DEBUG, and then at the
"hyphen prompt" (DEBUG's user-friendly interface), type a GO command,
-G=C800:5 (where C800 is the BIOS upper memory address selected by
jumpers on the controller). RLL drives can be defined optionally, with
the BIOS on the controller card disabled, in a user-definable or
custom CMOS drivetype. This version of SGATFMT4 supports RLL drives
that are fully defined in CMOS with the controller BIOS disabled.
In the case of ATA (IDE) drives:
ATA (IDE) drives can be divided into three separate scenarios: Early,
Swift and ZBR.
1. EARLY: When ATA interface drives (aka IDE - integrated drive
electronics, but so are SCSI's) were first introduced (ST157A family),
we strongly warned and cautioned against any attempt to lo-level
format the drives because 1) the factory written defect-mapping files
might be erased on reserved areas of the drive, and 2) the optimized
interleave and skewing values used would be forfeited giving slow
transfer rates. At this stage of development, SGATFMT4 lists these
drives only as a fall back option, in lieu of a factory repair format.
If the drive has somehow lost its original format, or the partition
structure been corrupted by a virus etc., SGATFMT4 could be used to
reformat _without_ the benefit of the defect mapping files. Any
defects will need to be "rediscovered" again; first, by the DOS high
level format and second, by a third-party disk scanning utility. These
utilities are quite likely to locate all of the hard errors, but
unlikely to find the soft errors. The only way to completely evaluate
a drive for both hard and soft error is by a factory repair with
extremely sophisticated diagnostic equipment. (See the glossary
section for HARD and SOFT ERRORS.)
2. SWIFT: As the ATA interface products became more sophisticated
with new technology and the introduction of the Swift drives (models
like ST1239A, ST1201A etc), lo-level formatting became pretty much
"half" of a problem. When these drives are in translation mode
(non-physical geometry definitions), a lo-level format is harmless to
the factory defect-mapping files and optimized skewing (albeit
destructive to user data) since it doesn't re-sector the drive. If,
however, the Swift drive is in true physical mode, then the lo-level
format will re-sector the drive.
3. ZBR: Finally, today's ATA interface drives (like the ST-1144A and
ST-3144A) are often Zone Bit Recorded (ZBR). ZBR drives, have variable
sectors per track, depending on the zone of the drive. The outside
tracks, being larger in circumference (i.e. track length is longer),
are able to hold more sectors than the innermost tracks. In this
scenario, it is IMPOSSIBLE to define the drive in CMOS setup with true
physical values. Cylinders and heads, yes.... but not the sectors per
track. Therefore, these drive are ALWAYS in translation mode and
immune to a re-sectoring lo-level format. On ZBR ATA interface drives
(Seagate, at least... others UNK), the factory defect mapping files
are fully protected, and since the drive is always in translation, the
optimized skewing is also protected.
As to defect management, most ATA interface drive's show 0 bytes in
bad sectors under CHKDSK. This is a courtesy reallocation or
"slipping" of bad sectors by the factory format, and not part of the
interface definition.
There are a few good reasons to consider a lo-level format for a ZBR
ATA/IDE drive. Because a lo-level will "data-scrub" all the sectors,
this may be the only way to delete a corrupted partition record, or
partition record from another operating system, or even a virus
infection. If a new defect surfaces, maybe from a head slap
(earthquake!), SGATFMT4 is able to find and lock out the offending
sector, provided the defect is not in the ID portion of the sector. In
this method, a kind of mid-level format, the locked out sector will be
found again during the DOS hi-level format and will indicate as "bytes
in bad sectors" at the conclusion.
==========================================================
ANATOMY OF A SECTOR
-------------------
The purpose of a track format is to organize a data track into smaller
sequentially numbered blocks called sectors. The beginning of each
sector is defined by a pre-written identification (ID) field which
contains the Logical sector address plus cylinder and head
information. The ID field is then followed by a user supplied data
field.
Anatomy of a Sector (17-sector, 512 byte/sector):
Index Index
┌┐ ┌┐
││ ││
┘└───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┘└─
│ 1 │ 2 │ 3 │ 4 │ 5 │ 6 │ 7 │ 8 │ 9 │10 │11 │12 │13 │14 │15 │16 │17 │
Gap1 │ │ Gap4
│ │
571 Bytes Total
┌────────────────────────────┘ └──────────────────────────────────────┐
(Field Types:)
┌Sync.──┬ID Field────────┬Gap2───┬Data Field──────────────────────┬Gap3─┐
│ 1 │ 2 3 4 5 6 7 │ 8 9 │ 10 11 12 13 14 15
(Field No.)
Field No. Bytes Field Description
1 13 ID VFO Lock A field of all zeros to synchronize
the VFO for the ID.
2 1 Sync. Byte A1h with a dropped clock to notify
the controller that data follows.
3 1 Address Mark FEh: ID data field follows.
4 2 Cylinder Address A numerical value in Hex defining
the detent position of the
actuator.
5 1 *Head Number A numerical value in Hex defining
the head selected.
6 1 Sector Number A numerical value in Hex defining
the sector for this section of
the rotation.
7 2 **CRC Cyclic Redundancy Check
information used to verify the
validity of the ID information
field just read.
8 3 Write Turn On Zeros written during format to
Gap isolate the write splice created.
This field assures valid reading
of field number seven and allows
the 13 bytes required for data
VFO lock.
9 13 Data Sync. A field of all zeros to sync the
VFO Lock VFO for the data field.
10 1 Sync. Byte A1h with a dropped clock to
notify the controller that data
follows.
11 1 Address Mark F8h: User data follows.
12 512 Data User Data.
13 2 **CRC Cyclic Redundancy Check
information used to verify the
validity of the user data field
just read.
14 3 Write Turn Off Zeros written during update to
Gap isolate the write splice created.
This field assures valid reading
of field number 13 and allows the
13 bytes required for VFO lock
for the ID field of the next
sector.
15 15 Inter-Record Gap A field of 4Eh which acts
as a buffer between sectors to
allow for speed variation.
Index : This is a signal which occurs once per revolution and it
functions to indicate the physical beginning of the track.
* Head Number : bits 0, 1, 2 = Head Number
bits 3, 4 = '00'
bits 5, 6 = Sector Size = '00'
bit 7 = Bad Block Mark
** CRC : These codes are generated by the controller, and written on
the media during formatting. Data integrity is maintained by
the controller, recalculating and verifying the ID Field check
codes when the ID Field is read. An acceptable polynomial is:
16 12 5
X +X +X +1
In the case of the Data Field CRC, instead of two bytes of
Data CRC, the controller may implement a multiple byte Error
Correction Code (ECC) Data Field integrity system. An ECC
system provides the possibility of data field read correction
as well as read error detection. The correction/detection
ability is dependent on the code chosen and the controller
implementation.
Gap1 : Provides a head switching recovery period and controller
decision making period, so when switching from one track to
another, sequential sectors may be read without waiting the
entire rotational latency time (additional time may be
required on 1 to 1 controllers by adding a head skew).
Gap2 : This gap follows the CRC bytes of the ID field and continues
to the data field address mark. Written by the controller, it
provides both a pad to ensure a proper recording and recovery
of the last bits of the ID Field check codes and to allow time
for controller decision making plus a byte for a write splice.
The write splice will be created on the media as soon as the
interface Write Gate is activated when performing a Data Field
update function.
Gap3 : Also known as the inter-record gap, this gap follows the CRC
bytes of the Data area. In addition to similarities to Gap2,
it also provides a means to accommodate variances in spindle
speeds. A track may have been formatted while the disk is
running slower than nominal, then write updated with the disk
running faster than normal. Without a gap, or if the gap is
too small, the sync bytes or ID field of the next sector could
be overwritten. The actual size of this padding, initially
provided by the format function, will vary, affected by on the
disk rotational speed variations when the track was formatted
and each time the Data Field is updated.
Gap4 : This is the speed tolerance gap for the entire track. It is
required to insure that the entire track can be formatted
during an Index Pulse to Index Pulse Track Format operation.
This Preindex gap will vary in actual size, depending on the
disk rotational speed (+-0.5%) and write frequency tolerance
(+-0.01%) at the time of formatting.
======================================================================
Obtaining updated versions
--------------------------
If this software is updated, the updated version
will be posted at the following sources:
* SeaBOARD-The Seagate electronic bulletin board systems
United States 408-438-8771
England 44-1-62-847-8011
France (+33 1) 48 25 35 95
Germany 49-89-140-9331
Singapore 65-292-6973
Thailand 662-531-8111
Australia 61-2-756-2359
Korea 82-2-556-7294
* The Seagate CompuServe Forum (type "go seagate")
* The Seagate ftp server (on the internet):
ftp://ftp.seagate.com
======================================================================
License Agreement and Warranty Disclaimer
-----------------------------------------
Seagate reserves the right to change, without notice, product
offerings or specifications.
This is a legal agreement between you the purchaser and Seagate
Technology, Inc. By accessing Seagate Technology SGATFMT4.EXE (the
"Software"), you agree to be bound by the terms of this agreement. If
you do not agree, do not access the software.
Seagate provides the accompanying object code of the Software and
nonexclusively licenses its use to you on the following terms and
conditions. The Software is Seagate's proprietary, copyrighted
product. Seagate grants you a limited access to use one copy of the
Software. You may not copy, distribute the Software for resale. You
may not reverse engineer, modify, rent, or lease the Software. In
addition, you may not disclose the information or data incorporated in
the Software to others, in any format.
You accept the Software "as is" without any warranty whatsoever.
Seagate does not warrant that the Software will meet your
requirements; that the Software is fit for any particular purpose or
that the use of the Software will be error free.
SEAGATE EXPRESSLY DISCLAIMS ALL WARRANTIES, WHETHER ORAL OR WRITTEN,
EXPRESSED OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF
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WILL SEAGATE BE LIABLE TO YOU, YOUR CUSTOMERS OR OTHER USERS IN ANY
WAY BASED ON USE OF THE SOFTWARE, INCLUDING WITHOUT LIMITATION FOR ANY
LOSS OF PROFITS, LOSS OF DATA OR USE OF THE SOFTWARE OR INDIRECT,
INCIDENTAL, CONSEQUENTIAL, SPECIAL, OR EXEMPLARY DAMAGES ARISING OUT
OF OR IN CONNECTION WITH THE USE OR INABILITY TO USE THE SOFTWARE.
End of License Agreement.
-=EOF: SGATFMT4.TXT=-