Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!apollo!weber_w
From: weber_w@apollo.HP.COM (Walt Weber)
Newsgroups: comp.sys.atari.st
Subject: Re: Atari ST DMA to SCSI conversion
Message-ID: <4653a8ee.20b6d@apollo.HP.COM>
Date: 19 Oct 89 20:49:00 GMT
References: <1989Oct17.062817.6540@cit5.cit.oz>
Sender: root@apollo.HP.COM
Reply-To: weber_w@apollo.COM (Walt Weber)
Organization: Hewlett Packard NARC @ Apollo Systems Division
Lines: 24
Keywords: ST DMA-SCSI

In the referenced article ben@cit5.cit.oz (Nino Benci) writes:
>Can anyone please help me with info on converting the Atari ST DMA port
>to something which looks and operates like a SCSI port.

The Atari DMA port (ACSI) isn't SCSI.  Its layout of the command block does
not reserve the first byte for the OPCODE, but instead places the target
logical unit number in the high 4 bits and the opcode in the low 4 bits of
the first byte.  There are also differences in the physical connection, but
I'm doing this from (very hazy) memory and don't wish to mislead you.

I believe that the best approach for you would be to use either the ICD disk
controller or the Berkley Micros Systems 200 disk controller.  I KNOW that the
BMS 200 will permit you to issue full SCSI commands, and I suspect that the
ICD board will also permit that (assumption is based on ICD's tape backup
system requiring SCSI commands not permitted in the ACSI scheme).

I haven't any information on how to purchase either of these in Australia.  I
would, of course, be willing to purchase one here for you if you will fly me
there to hand-deliver it :-)

...walt...
Walt Weber               Hewlett Packard NARC @ Apollo Systems Division
(508) 256-6600 x8315     People's Republic of Massachusetts
-The views expressed herein are personal, and not binding on ANYONE-