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From: wallace@oldtmr.dec.com (Ray Wallace)
Newsgroups: comp.sys.atari.st
Subject: Re: SH 204 Upgrade
Message-ID: <1359@engage.enet.dec.com>
Date: 15 Nov 89 19:17:57 GMT
Sender: news@engage.enet.dec.com
Organization: Digital Equipment Corporation
Lines: 58


In article <212@trwrb.UUCP>, root@trwrb.UUCP (root) writes...
>I want to upgrade my 20 meg SH 204 harddrive to about 40 meg.  I hoped I
>could do this by simply replacing the Drive Mechanism
You can.
>   * Should I install a 40 meg Tandom hard drive? 
The replacement drive does not have to be a Tandom. It can be any hard drive
with a ST506 or ST412 interface. These are "standard" drives/interfaces (ie:
most hard drives fit this description unless they are specified as a SCSI
drive/interface).
>   * Can I install a Seagate drive?
Yes!
>   * Which models?
Any model as long as it does not have a "N" suffix which indicates it is a
SCSI drive (ie: has an embedded SCSI controller).
>   * Will I need more parts?
No.
>   * Can I daisy chain the SH 204?
You can add a second drive to the SH204 by running cables from the second
drive into the SH204 box and connecting to the controller.
>   * Will I need different software?
What ever software you use you will need to know some specs on the HD (# of
heads, # of cylinders/tracks, etc..) in order to configure/re-configure the
formatting program. It's been a while since I used the Atari HD software so I
don't recall if it can be re-configured. You could use the software from Supra
or ICD (pre-V4 versions) which can both be easily configured for any drive.
Both Supra and ICD software already know the parameters to a lot of different
drives so all you have to do to configure for your drive is click on the make
and model number (if your drive is listed). Otherwise there is a .DAT file you
will have to edit and add a line for your drive (not difficult to do).

You should also be careful to get a drive which does not use more than
2 Amps of current on the 12 volts. Some half height 5 1/4 drives will be okay,
most 3 1/2 drives will be fine, most full height 5 1/4 drives will draw too
much current and are likely to ruin the power supply inside the SH204.

Actually you can use a SCSI drive but a SCSI drive must be connected directly
to the host adapter board (the smaller of the two boards) inside the SH204
instead of being connected to the controller board like your current drive is.

Replacing the existing drive is just a matter of pulling out the old one and
plugging in the new one, and then configuring the formatting software to be
able to configure your drive.

Adding a second drive is a little more work but not difficult. The second
(non-SCSI) drive needs to be connected to a second power supply. There are
two cables to connect between the second drive and the controller. The
controller has a "spare" connector for the smaller of the two cables but for
the larger cable you will have to "tap into" the existing cable (clamp a new
connector onto the middle of the cable, a small vice works good for this if
you are careful).

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Ray Wallace		
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