Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!leah!rpi!pawl9.pawl.rpi.edu!ncc1701
From: ncc1701@pawl.rpi.edu (Mark O. Chadwick)
Newsgroups: comp.sys.tandy
Subject: Re: Tandy hardware
Summary: Double-sided drives
Message-ID: <4708@rpi.edu>
Date: 19 May 89 20:03:30 GMT
References: <25039@ccicpg.UUCP>
Sender: usenet@rpi.edu
Distribution: na
Organization: Rensselaer Polytechnic Institute, Troy, NY
Lines: 32

In article <25039@ccicpg.UUCP> paulm@ccicpg.UUCP (tmp Paul Moreau usenet acct) writes:
>	I bought a model 4 recently and would like to upgrade it to
>	model 4D.  My question is this:
>	   Is the only difference the DOUBLE sided drives ?
>	   If I put 2 48 tpi (PC XT types) Double sidded drives into
>	   my model 4 will the disk controller know how to handle it ?
>	   Does TRS-DOS 6.2 or LSI-DOS 6.2/3 know ?

I tried to put some different disk drives in the system, too.  I had a 
pair of double-sided 96-tpi drives (80 tracks) which I added on to my
Model IV.  The DOS has no problem with using double-sided drives, even
though it took a call to Radio Shack to discover that, since I got an old
DOS manual with my TRSDOS 6.2  So, I formatted some disks as double
sided, and then stuck the drive into the cabinet to replace the originals.
The problem was, that the BOOT routine in the ROM does not know that these
are double-sided drives, and hence gets confused when it needs to read
the second side.  If you can figure out a way to get all the important
stuff onto one side so the machine can boot normally, and then use the other
side to store data, you should be okay.  I didn't have time, and TRSDOS 6.2
didn't seem capable of handling as much data as I was asking it to (it
trashed one of my backup disks totally by writing over stuff already there)
There is also something you have to do about the internal cable to the
drives which caused some kind of problem.  If you have the tech manual, you
should be able to figure out what it was...I can't remember, and I don't
have my manual here...sorry
GOod luck.


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ncc1701@pawl.rpi.edu       | Live long and prosper, Spock
USERGDES@rpitsmts.bitnet   | I shall do neither.  I have killed my
 (Mark Chadwick)           |    captain...and my friend