Path: utzoo!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!wuarchive!sdd.hp.com!hplabs!pyramid!prls!gordon
From: gordon@prls.UUCP (G Vickers)
Newsgroups: sci.electronics
Subject: Re: Radio Shack Model 100
Message-ID: <50889@prls.UUCP>
Date: 6 Mar 91 18:43:09 GMT
References: <1809@valhalla.megatek.uucp>
Reply-To: gordon@prls.UUCP (G Vickers)
Organization: Philips Research Labs, Sunnyvale, California
Lines: 55

In article <1809@valhalla.megatek.uucp> cjp@megatek.UUCP (Christopher J. Pikus) writes:
>
>	I'm thinking of getting a R/S Model 102(?) and am interested
>in what hardware/software mods have been done to one. Would some
>of you netters be so kind as to post details of some of your Mod100
>projects. In particular I would be interested in:
>

      Model 100 ?   YECK !

      I used about fifty of these in a data collection project. I became
   VERY familar with the thing as I had to look into the ROM and
   DOS byte by byte.  I am less familiar with the 102 since my
   program (written with a cross-assembler on a VAX and force feed
   to the Model 100) ran on it without modification.

     I beleive I found some OS bugs in the model 100, I do not know if
   they were fixed in the 102.  When I called Tandy (before the 102
   was introduced), they really didn't seem to care about the bugs).

    The Model 100 (102) is fine for taking notes in class and then
   transfering the notes to a bigger computer for editing and saving.
   I've had to cold start the 100's and 102's so many times, I would
   not consider any RAM files safe until they are saved to disk or
   to another machine.

     If you plan to use the serial port, or anything else that can cause
   interupts, be forwarned that (at least in the 100) the machine may
   go to la-la land and require a cold start that will wipe out all
   directory entries you have created.  Under these same conditions,
   a less sever (but more common) problem may occur: the keyboard
   doesn't always recognize keypresses.  The machine uses an 8155 to
   drive a buss that scans/reads the keyboard, sets/reads the clock,
   and some other things (I don't have my notes handy).  It is a cleaver
   scheme but during one small portion of the clock read routine, the
   buss can remain hot should an interupt occur.  This problem was
   first discovered while running an BASIC program.  The fix, if you
   are running interupt intensive programs, is to write your programs
   in assembler and include you own interupt code, i/o code, math
   fuctions, etc.  i.e. don't let the ROM code run  :-)

 DISCLAIMERS:
  Since dis-assembling the ROM code is prohibited by the license
     agreement each owner is bound too, do not assume I did it anyway. 
     Don't ask me for any such listing since Tandy's copywrite would
     prohibit sharing it if I did have one.
  These are my opinions only. They also rely in part upon
     information provided to me by those who worked for me on this
     project so I COULD BE WRONG.
 

Gordon Vickers 408/991-5370        {mips,pyramid|philabs}!prls!gordon  
Signetics in Sunnyvale,Ca (USA)
The Earth is a complex array of symbiotic relationships: Every extinction,
  whether animal, mineral, vegetable, or cultural hastens our own demise.