home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
EnigmA Amiga Run 1996 June
/
EnigmA AMIGA RUN 08 (1996)(G.R. Edizioni)(IT)[!][issue 1996-06][EARSAN CD VII].iso
/
earcd
/
hardware
/
scsitowr.lha
/
SCSITower.txt
Wrap
Text File
|
1996-05-07
|
15KB
|
366 lines
***********************************************************
* *
* Build Your Own SCSI Tower with a CD-Rom & Hard drives *
* *
***********************************************************
$VER: SCSI Tower V1.0 (Written by Anthony Keeley)
Want to add a second SCSI hard drive to your system, or even a CD-drive, or
both? Have you seen the nice adverts wanting to sell you a PC case with CD-Rom
drive, with connecting cable and/or SCSI controller for a very nice price?
Then here's how you could do it yourself, and save a bundle on that very nice
price.
Requirements:
An Amiga. Whilst this document can be used by PC & MAC people, the software
referred to is Amiga only. You'd have to refer to your own on how
to set up the drives, installation software, drivers, windows
etc, etc.... zzzzZZZZZZ.
SCSI Controller with external Port (eg: A590, GVP, Supra, Oktagon, A2091 etc)
(This, like the Amiga, you should already have.)
External SCSI Drive(s) / SCSI CD-Rom Drive (both is nicer :)
1 x PC Case. (Shape and size dependant on your requirements/cash)
1 x SCSI ribbon cable. A pre-made ribbon with 7 x 50 pin connectors on.
(with connectors) This type usually has an 8th connector for connecting
to an external cable to. This 8th connector should
be a Centronics 50 way female connector.
1 x 25 D type female to a 50 way Centronics connector male.
If you plan on using a Squirrel SCSI interface (A1200 & A600) you won't
need this last cable, as the Squirrel is already fitted with the correct
type of Centronics connector.
Method:
Before you start anything, check the SCSI ids of each of your drives that you
intend to connect, including any drives that you already have connected. CBM's
HDTooBox will list all the drives on the particular controller you intend to
use. WRITE THEM DOWN, BEFORE YOU SWITCH OFF!
Change the ID on the drive(s) so there are no matching id's. The controller
is usually ID 7 so don't use that. The drive that came with the controller
originally (if it came fitted) should be ID 0. (See later about changing ID's)
Most CD-drives come set as ID 2, and personally I think this was a stupid idea
hanging over from the PeeCee's. I'd strongly recommend changing it to ID 6
(the last in line).
Open your PC case and install the drive(s) into the appropiate drive bays, not
forgetting to connect the power connectors. Both connectors will only fit in
one way due to their design.)
With Tower Cases, the fastening screws are provided and you should use four
screws for each drive installed. Desktop cases can vary on how drives are
installed, so check before you buy that you'll have everything provided in the
initial purchase.
Get your internal SCSI cable and connect it to the drives. Common sense will
tell you how to connect the drives to the cable. If you can't manage this, I'd
give up and get someone who knows.
Before closing the case, you'll have to determine how to get the connector to
the outside of the case so you can make the connection to the controller.
With Towers, the ribbon cable can sit between the outer casing and the frame
of the tower. Or, both the tower and desktop cases have a section for
expansion cards to be fastened too. Most should be removable, so you can put
the ribbon cable under the frame to the outside world. DON'T refasten the
screws too tight near the cable!
Finally, you can connect the external scsi port on your controller to the
connector at the back of your case using the 25 to 50 way cable. (The Squirrel
should connect directly)
Before you put the casing back on, boot up your Amiga and watch and listen
very closely. Your machine will take some time to boot the first time due to
the drives not being set up, and the controller trying to determine what on
earth a CD drive is and why it wasn't told about it.
OR
Problem : Your machine simply won't boot...
Cure 1 : You've managed to allocate a SCSI id the same as your boot drive.
Cure 2 : Switch on the PC case
Cure 3 : A termination problem (see later - Termination)
Uncure 1 : The drive has such a big clash with the controller that both
refuse to work, and the machine fails to boot.
OR
Problem : Your machine boots but HDToolBox doesn't see the added drives...
Cure 1 : Wrong SCSI device set in HDToolBox's Icon.
Cure 2 : Cable not connected
Cure 3 : SCSI id set to the same as another drive (not the boot drive)
Cure 4 : A termination problem (see later - Termination)
Uncure 1 : The drive added is a non-worker
Uncure 2 : The drive added won't work with your controller
OR
Problem : Your machine displays a purple screen with a floppy being inserted
into a floppy drive.....
Cure 1 : Possible loose SCSI connector, or Power connector.
I've only ever suffered this problem once, and the first thing I
did was to check the connections and try again: the machine booted.
Cure 2 : A possible termination problem (see later - Termination)
Any or all of the above problems can be caused by the ribbon cable being
ripped where it joins the actual metal pins inside the connector. If you
suspect you have got a ripped cable, then you can try one of two things to find
out. Firstly you can take a multimeter and test each and every even numbered
connector, or if you have a spare connector which sits inline before the
suspected connector, connect your drive to this one, remove any drives after
the suspected one, and switch on to see if this has cured your problem!
So you've managed to boot up, and HDToolBox has found the added drives but
says they are UNKNOWN. Brilliant! Exactly where you should be (unless they
were already used on another Amiga, in which case HDToolBox should say they are
CHANGED).
Using HDToolBox click on the UNKNOWN drive and then select 'Change Drive
Type'. Now select 'Define New': select 'Read Configuration' and the boxes
should fill with the information required by HDToolbox to work with this drive.
Select OK, OK, and then 'Save Changes to Drive'. If you want to partition the
drive, away you go and divide the drive up into as many pieces as you want by
selecting 'Partition Drive'. Repeat this process for all UNKNOWN Drives.
Quitting from HDToolBox will force a reset, but this is so the system gets to
recognise the new drives.
For the CD-Drive, you'll have you use one of the CD filesystems provided, such
as Xetec, AsimCDFS, AmiCDFS, or you could simple use CBM's dos driver (if you
have Workbench 3.1). If you do use CBM's dos driver, remember to change the
device and SCSI id in the tool types of the icon.
One final reset and everything should be working ok. But your boot up will
take longer because of the added drive(s).
CD Hints:
1. Don't put your CD dos driver into the DEVS:DOSDRIVERS drawer. Put it
into SYS:STORAGE/DOSDRIVERS, this will allow a slightly faster boot
up: and if you need the CD, you can simply double click on the icon.
2. If you do have your CD dos driver in DEVS:DOSDRIVERS, put an Amiga
CD in, this will help reduce the boot up time.
Changing SCSI ID's:
With all the internal drives I've seen, ID's have to be changed using jumpers
either next to the SCSI connector (CD drives) or on the circuit board (hard
drives). Referring to the manual/A4 sheet that came with the drive (you did
get one didn't you?) will tell you where the jumpers are and how to set each ID
And for those of you, who like me bought their drives second hand without
instructions....
ID jumpers come in a set of three, they can be anywhere and they can be part
of a row of other jumpers, but there are clues as to where they are: as is the
case with Quantums which have a row of six jumpers, and the ones marked A0, A1,
A2 are for the id, whilst the other three have other usages.
Ok, you've located your jumpers and want to work out how to change them to a
particular ID. The following chart will show you which jumper has to be open
(Not Connected) and which has to be closed (connected) to get the correct ID.
We'll use Quantums marking for this chart..
\ ID 0 1 2 3 4 5 6
\
Jump \
A0 O C O C O C O
A1 O O C C O O C
A2 O O O O C C C
Get the Ids write and thats the battle nearly won!
Termination (or how this standard does NOT work):
SCSI termination is a very BLACK art, and for a very good reason!
SCSI termination working on the principle that both ends of the chain should be
terminated to stop signal echo's. A simple example would be as in example 1
Terminated Terminated
-------------- --------------
| Controller |----------| Hard drive |
-------------- --------------
But if you add a second drive, example 2 should be the result.
Terminated Unterminated Terminated
-------------- -------------- --------------
| Controller |----------| Hard drive |----------| Hard drive |
-------------- -------------- --------------
Sadly, as the chain gets longer, Termination "rules" seem to go out of the
proverbial window. Looking at my two present setups (Yes! I have two towers,
both attached to two Amigas) both using very funny termination sequences.
One via the GVP HD8+ II controller, and the other via the Classic Squirrel.
Tower1:
Unterminated Terminated Unterminated Terminated
-------------- -------------- --------------- --------------
| Hard drive |----| Controller |----| CDRom drive |----| Hard drive |--\
-------------- -------------- --------------- -------------- |
|
Unterminated Unterminated |
-------------- -------------- |
| Hard drive |----------| Hard drive |--/
-------------- --------------
Tower2:
Terminated Unterminated Unterminated
-------------- --------------- --------------
| Controller |----| CDRom drive |----| Hard drive |--\
-------------- --------------- -------------- |
|
Unterminated Unterminated |
-------------- -------------- |
| Hard drive |-----| Hard drive |--/
-------------- --------------
Yes, the second tower only uses 1 set of termination, and NO, I don't suffer
any problems whatsoever. So the Termination "standard" is something of a hit
and miss subject. My recommendations for termination is to remove/disable ALL
termination, except for the controller (which is usually soldered on anyway),
and only add to one drive at a time (starting with the last drive first, and
remembering to remove it from the previous drive) until you solve the problem
you are having.
Building Cables:
I'm not going to tell how to build a cable for this project, but I can show
you the connectors types, and the pinouts to make up a 25 way to 50 way
connector.
SCSI ribbons have 50 wires, wire 1 is the cable marked with a secondary colour
such as a red or blue stripe down the side. Be careful not to purchase
security ribbon as this isn't flexible enough to be used.
D type 25 pin connector
_____________________________
13 \ o o o o o o o o o o o o o / 1
25 \ o o o o o o o o o o o o / 14
This D type connector was used by Apple, but seems to be taken on by the Amiga
as the standard external connector for SCSI.
Internal 50 pin SCSI connector
------------------------ --------------------------
49 | o o o o o o o o o o o o o o o o o o o o o o o o o | 1
50 | o o o o o o o o o o o o o o o o o o o o o o o o o | 2
-----------------------------------------------------
All odd pins are on one row, all the even are on the other.
Making up a ribbon cable using these header blocks, allows you to set the
connectors to exactly the correct spacing you need. Sadly, adding one of these
connectors without the proper tools can leave you suffering from ripped cables,
bad connections, and a lot of headaches when it comes to booting up. I've only
managed to get 2 out 7 connected correctly, and I still have some suspicions
about them.
Centronics 50 pin connector
_________________________________
1 \ / 25
\ +++++++++++++++++++++++++ /
26 \ __________________________/ 50
SCSI I (and most SCSI II) Drives all use a 50 pin connector to connect it to
the SCSI bus. The pin-out below shows you which wires to connect to which pin,
to connect it to the Controller.
25 to 50
1 - 48
2 - 42
3 - 50
4 - 40
5 - 38
6 - 36
7 - GROUND (20, 22, 24, 28, 30, 34)
8 - 2 --
9 - GROUND (20, 22, 24, 28, 30, 34)
10 - 8 --
11 - 12
12 - 14
13 - 16
14 - GROUND (20, 22, 24, 28, 30, 34)
15 - 46 --
16 - GROUND (20, 22, 24, 28, 30, 34)
17 - 32 --
18 - GROUND (20, 22, 24, 28, 30, 34)
19 - 44 --
20 - 18
21 - 4
22 - 6
23 - 10
24 - GROUND (20, 22, 24, 28, 30, 34)
25 - NOT USED (26) * --
* note: Pin 26 is labelled either TERMPWR or N/C (Not Connected) in my manual.
I have connected this, and have suffered no problems (yet!). I suggest you
leave this N/C unless you experience problems getting your drive(s) to work.
Getting In Touch:
I have put a lot of thought into this document to make it as easy to use as
possible, and I'm sure there are SCSI experts out there who are screaming in
agony over my methods of SCSI TERMINATION. And there'll be the odd one or two
who'll say I'm talking rubbish: and there'll be those of you who need some
more help or guidance in this project. So if you want help, email me at the
address below and I'll help as much as possible. And those who want to send me
advice and info, I'll be only too glad to read what you have to say and learn
from it. You can even send me abuse if need be: I can quite happily delete
those messages faster than you can write them. Anyway, before I babble on
anymore, here's my contact address..
Anthony Keeley (My name, just in case you'd like to use it)
Snoopy@mail.on-line.co.uk (my email address, if you hadn't guessed)
I look into my mailbox most days, so you should get an answer within 2-3
depending on how difficult it is to answer.
Anthony...