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From: johnk@loki.atmos.ColoState.EDU (John Kleist)
Newsgroups: comp.sys.apple2
Subject: Retro Computing, A/D and MIDI
Message-ID: <8088@ccncsu.ColoState.EDU>
Date: 24 Jul 90 17:49:51 GMT
Sender: news@ccncsu.ColoState.EDU
Reply-To: johnk@loki.Atmos.ColoState.edu
Organization: Dept. of Atmos. Science, Colorado State
Lines: 32

I recently (re)acquired an Apple ][+.  My intent was to build a camera
shutter tester for a friend who is a camera repairman.  A photodiode and a
transistor were connected to the game port.  A little assembly for the
timing loop (I love Big Mac) and some Applesoft for the rest. WOW! It works!

I find that hacking on the Apple is FUN.  Much more fun than banging away 
on a unix workstation or playing with my Amiga.  This sort of fun is what
originally attracted me to computing.  Although GUI's, high level languages,
and multitasking operating systems are wonderful things, they impede joyous
hacking.  Why type in pages of code when all you want to do is sample the
high order bit at location $C062?

I am now considering using it as a MIDI device.  This would involve adding
several A/D channels to set contoller values, building or buying a MIDI
interface and possibly speeding up the CPU to handle contoller messages.
I have several questions:

1) Has anyone built a A/D device for their Apple?  I need 8 or 16 channels
of 8-bit conversion at a moderate sampling rate, <1 khz.  What chips are
easy interface to a 6522 VIA?

2) Which of the MIDI interfaces will work with my Apple ][+?  Are these easy
to build?  Do the commercial ones buffer incoming MIDI messages?  Is MIDI
interface programming similar to serial port programming?

3) Do these ZIP chip things really work?  What is the REAL speed up factor
on REAL programs, say a BASIC program?  Do they somehow speed up memory
access time as well as CPU cycles?



John Kleist     johnk@loki.atmos.colostate.edu