Path: utzoo!utgpu!water!watmath!mks!wheels
From: wheels@mks.UUCP (Gerry Wheeler)
Newsgroups: comp.sys.atari.st
Subject: Re: BMS controller package
Summary: How to build a disk...
Message-ID: <348@mks.UUCP>
Date: 18 Dec 87 18:57:49 GMT
References: <3217@batcomputer.tn.cornell.edu>
Organization: Mortice Kern Systems, Waterloo, Ont.
Lines: 71

There have been two requests for hard disk info recently, and since I
can never figure out how to email to bitnet, I'll post a common
answer to both...

> I am interested in building a hard disk system based on something like
> the BMS ACSI to SCSI DMA converter.  I would like to know what one would
> need besides the board (such as cables and type of hard disk system) to
> get a disk going.  Also, what other boards are there like the BMS board?
> 
> Bob 
> also known as UD138985 at NDSUVM1. 

> Has anyone had any experience with BMS and the package they sell that allows
> one to use a cheap IBM-PC style drive to hook to an Atari ST?  I'm
> interested but would like more details about the BMS hardware and the prices
> and the difficulty involved in hooking everything up (oh and what other
> hardware, power supply, case, etc is needed)?  Thanks . . .
>                                 Adam
> engst@tcgould.tn.cornell.edu

I built my hard disk system this way because I already had most of the
parts. If you're going to buy everything from scratch, then the cost
may exceed that of the commercial hard disks. However, the home-built
type may be more flexible.

All the hard disks work like this: (this paragraph is open to correction
by more knowledgeable people!): the DMA output of the ST, known as ACSI,
feeds to an adapter board.  This board converts the protocol to SCSI, a
standard disk interface protocol.  The SCSI cable connects to the disk
controller.  The Adaptec 4000-series controllers is usual.  The
controller then connects to the disk.  If you look inside the commercial
units, I think you will find this arrangement packed in there. 

The disk drive can be almost any unit that uses the st406 or st512
interface.  (Is that the right number? Anyway, same disks used by IBMs.)
You may be able to use a disk with an SCSI interface by omitting the
Adaptec controller, but I haven't seen it done. 

By the way, the BMS adaptor board includes a battery operated clock,
and I haven't had to set the time since I put it together.

So, total parts are: ACSI cable from ST to adaptor, adaptor board
($140), 50-conductor SCSI cable to controller, controller board ($125?),
34- and 20-conductor cables to hard disk, disk ($300?), power supply
($50?), cabinet. 

As mentioned in the posting, adaptor boards are available from Berkeley
Microsystems.  I have also seen the adaptors from the commercial drives
available.  Adaptec controllers are available from BMS and others. 
Power supplies and cables can usually be found locally. 

By the way, the Adaptec controller will support 2 hard disks.  They must
be very similar, as there are some jumpers on the board which affect
both drives.  Just make sure your power supply has enough reserve if you
plan to go this route. 

My system started out as an outboard drive for IBM PC's.  It included
the Adaptec controller (possibly damaged), and an Ampex Pyxis 13 10-meg
disk, and a blown power supply.  I added a new supply, had the
controller checked out by Adaptec, bought the BMS board, and voila.  I
have since upgraded to a Seagate ST238 20-meg drive, and I have enough
space and power to add another.  (That's what I meant about being more
flexible.)

If seeing the insides of a computer makes you queasy, don't go this
route.  If you think you can plug things together, this may be for you. 
-- 
     Gerry Wheeler                           Phone: (519)884-2251
Mortice Kern Systems Inc.               UUCP: uunet!watmath!mks!wheels
  43 Bridgeport Rd. E.                          BIX: join mks
Waterloo, Ontario  N2J 2J4                  CompuServe: 73260,1043