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From: john@monuxa.UUCP (John Ruschmeyer)
Newsgroups: net.micro
Subject: Re: Questions on TRS-80 Model I and Sinclair ZX81
Message-ID: <315@monuxa.UUCP>
Date: Sat, 20-Sep-86 22:51:35 EDT
Article-I.D.: monuxa.315
Posted: Sat Sep 20 22:51:35 1986
Date-Received: Tue, 23-Sep-86 23:23:16 EDT
References: <3767@brl-smoke.ARPA> <108@dosadi.UUCP>
Reply-To: john@monuxa.UUCP (John Ruschmeyer)
Organization: Monmouth College, West Long Branch, NJ 07764
Lines: 59

In article <108@dosadi.UUCP> root@dosadi.UUCP (Maintenance Account) writes:
>> 	First - A TRS-80 Model I... 
>> 
>> 	Questions:  How, where and from whom can my friend purchase a master
>> drive (RS SN 26-1160), and how much would they cost?  If someone out there has 
>> an old one they want to get rid of, this is fine too...  
>
>All of the Radio Shack machines (even the old model 1) use regular disk
>drives.  You can get any regular 40 track 5 1/4 inch disk drive 
>(no apple drives,
>they aren't standard) and plug it in.  Your drive 1 can also work as
>drive 0 (assuming you could live with one drive).  If you add on a drive,
>make sure that only the last drive on the chain has the little terminating
>reisistor in it (It's the only socketed item on the logic board, if I
>recall correctly).  You'll also need a copy of TRSDOS if you don't already
>have one.
>
>If you want to use something with the Radio Shack label on it, Color
>Computer addon disk drives work in the model 1.

Just a few more notes:

As stated in the quoted followup, the disk drives used on all of Tandy's
machines are standard 40 track 5.25" drives. The only difference between
the 26-1160 (drive 0 for the Model I) and the 26-1161 (what you probably
have) is the presence of a terminating resistor pack on the 1160. (It is
definately socketed on the later drives- I couldn't findd it on my ancient
26-1160.)

(Does anybody know the purpose of the terminating resistor? I notice that
if I try to use the 1161 without the 1160, the motor spins constantly.)

Some suggestions:

If you want a realy Tandy drive- try looking for a model 26-1164 drive.
This is drive 3 (first outside drive) for the Model III and Model 4 and
should contain the terminating resistor. (It is also a 40 track drive-
early Model I drives were only 35. No imcompatability- just more storage
space if you use a non-Tandy operating system.) 

Failing that- try looking for a Drive 0 for the Color Computer. It too, has
the requisite terminating resistor. The problem here is getting it without
the Disk Controller Pak for the Coco. From Tandy, you will probably need to
order it as a repair part. Better, probably is to pick up a copy of a
magazine called RAINBOW (devoted to the Color Computer) and look for a
third party supplier.


Hope this has been some help.

-- 
Name:		John Ruschmeyer
US Mail:	Monmouth College, W. Long Branch, NJ 07764
Phone:		(201) 571-3451
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						   ...!pesnta!moncol!john

	Actually, I know a lot about what turns a woman off.
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