Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!rochester!rit!ultb!clf3678
From: clf3678@ultb.UUCP (C.L. Freemesser)
Newsgroups: comp.sys.atari.st
Subject: Re: 3-1/4 drive prices.
Summary: Simple drive tutorial
Keywords: Disk drives
Message-ID: <552@ultb.UUCP>
Date: 31 Mar 89 02:03:42 GMT
References: <1227@ns.network.com> <28593@ucbvax.BERKELEY.EDU> <610@stag.math.lsa.umich.edu> <11661@pasteur.Berkeley.EDU>
Organization: Rochester Institute of Technology, Information Systems
Lines: 46

A few questions came up about hooking up a PC/XT mech to an ST.  Since
I have done this, and have done ALOT of research into this, I'll put in
my two cents worth of info.

Simply put, the ST has a built-in drive controller.  This means that the
disk drives we use are "dumb drives", obeying whatever the computer
tells it to do.  This is a great opportunity for hardware hackers to
build their own drive.

All you have to do is get a 720k mechanism, a power supply that has +5
and +12 lines (like a PC power supply), and a data cable.

The mech is probably the worst part of the thing.  Some will work, some
won't.  It's a matter of research:  find out what others have tried and
succeeded with, and use these mechs. 

The cable is easy.  Since the ST uses the standard signals from the
drive in its own arrangement (that wonderful 14 pin connector), all you
have to do is get an ST drive cable, cut off one connector, and hook up
a 34 pin header connector.  Best Electronics sells a "PC-Ditto cable
kit" for $10.

The power supply is also easy.  Grab a PC power supply and plug it in
straight away.  Since the connector on the power supply is not the same
as the one on the drive, you might have to do a little soldering.  If
you buy a new mech, it will come with an installation kit with the power
cable adapter.  If you don't get a kit, then you can solder the wires
from the power supply to the pins on the drive's connectors.

That's basically it.  Be sure to set the DRIVE ID (usually a jumper on
the drive itself) to D0.  The ST identifies the drive number by
switching around the wires in the cable (The computer's D1 [disk 2] wire
hooks up to the d0 [drive 1] wire on the second floppy).  Understand?

If you do NOT have TOS 1.4, you need to run a jumper from pin 2 to 28 on
the drive's 34 pin connector.  This connects the media change and write
protect signals.  You might run into a problem here if the signal isn't
strong enough to reach the computer.  That's where knowing what mech to
use is important.

By the way, I use a TEAC drive sold as the Tandy 1000EX external drive.
I also use a wall transformer power supply (a "brick") that I bought at
a local electronics place for $7.50.  The cable is a home-brewed hack,
but it works.

=cf=