Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!usc!sdd.hp.com!hplabs!pyramid!infmx!bruceb
From: bruceb@informix.com (Bruce Barr)
Newsgroups: comp.sys.tandy
Subject: Re: Model 100: How to interface with system bus?
Keywords: Model 100, system bus, peripherals
Message-ID: <1991Mar7.202223.11318@informix.com>
Date: 7 Mar 91 20:22:23 GMT
References: <23244@well.sf.ca.us> <1991Feb10.203444.18109@daffy.cs.wisc.edu> <1991Mar5.130348@snoc01.enet.dec.com>
Sender: news@informix.com (Usenet News)
Organization: Informix Software, Inc.
Lines: 36

In article <1991Mar5.130348@snoc01.enet.dec.com> cameronjames@snoc01.enet.dec.com (James Cameron) writes:
>In article <23244@well.sf.ca.us>, tswift@well.sf.ca.us (Theodore John Swift)
>writes:
>>Please help!  I'm trying to attach peripherals (A/D converters, analog
>>multiplexers) to the system bus socket of a Model 100. 
>
>Me too.  I want to make a MIDI interface.  I intend to model it on the design
>published in the MISOSYS Quarterly (V.i) for TRS-80's.  I need to know what I/O
>controller chip I can use to replace the Z80-SIO that that design calls for. 
>The 80C85 processor on the Tandy 102 that I have uses a multiplexed address and
>data bus.
>

(More deleted)

Actually the clock on the built-in serial connector can be software programmed
to work as a MIDI port.  It isn't exact, but is within the tolerances of the
MIDI standards.  I read a piece in the Model100 magazine about doing this.
Later I mentioned the posibility to a friend I have that is at the Stanford
U. Electronic Music Lab. (CARMA) and he ran with the idea!  I was out to
visit last month and he showed me a small connector, hardley bigger than a
25pin RS-232 connector and the two MIDI sockets.  Drew all power from the
RS-232 and provided the needed isolation/drivers.  He did say that it was
mostly just to see if he could do it, and that the software he had developed
had pretty much pushed the limits of the machine.  Uses it to monitor MIDI
signalls and such.

Hope this helps.

BB

P.S. I have no idea how his software development was done.  It is worth noting
     That I sold him an old KIM-1 years ago that he used in converting an
     old PAIA keyboard to MIDI.  Wrote all of the 6502 code by hand.  Included
     and extra 2K of Static Ram he added to get all the features he wanted.
     His code for the Model 100 might not be pretty, but I bet it's fast...