Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!tut.cis.ohio-state.edu!att!laidbak!elaited!daveb
From: daveb@elaited.i88.isc.com (Dave Burton)
Newsgroups: comp.sys.tandy
Subject: Re: Tandy 6000 hard disk replacement
Keywords: ST-251 hard disk Tandy-6000
Message-ID: <1989Nov27.164743.6533@i88.isc.com>
Date: 27 Nov 89 16:47:43 GMT
References: <2262@scicom.AlphaCDC.COM>
Sender: usenet@i88.isc.com (Usenet News)
Reply-To: daveb@i88.isc.com (Dave Burton)
Distribution: usa
Organization: Interactive Systems Corporation, Naperville, IL
Lines: 31

In article <2262@scicom.AlphaCDC.COM> fox@scicom.AlphaCDC.COM (David L. Fox) writes:
|I am trying to replace the 15 Meg hard disk in my Tandy 12/6000 external
|disk unit.  A posting of a few weeks ago indicated that this should be
|straightforward but I have encounterd a problem, namely three discrete
|wires soldered to the drive electronics board and connected to the controller.
|The previous posting did not mention anything like them and I am unsure
|of what to do about them.
|
|My new drive (a ST-251) will not work without them (I get "drive not ready"
|messages when I try to format). Any help or information will be appreciated.

NOTE: The following assumes an old style 8x300 based controller.
      I haven't worked with the newer WD1100 based controller.

The three wires may be profitably clipped at the original drive.
They provide signals/control lines for the green active light
and disk write protect (and the WP light?). I assume you did this
already, since you have the 251 connected, presumably installed.

HOWEVER, you will need to modify your controller card to enable the
non-Tandy HDs. It's been awhile since I did this, so I don't remember
exactly what pin I had to change. The essence of the hack was to tie
one of the pins on (each) data (20 pin) header on the controller to either
ground or +5 (I forget which). The fix was rather obvious from the schematics;
refer to the tech ref manual for the 12M external.

Sorry I can't be more explicit. I will attest that an ST-225 works great
with the 8x300 HD controller once mods along these lines are made.
-- 
Dave Burton
uunet!ism780c!laidbak!daveb