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From: doug@edge.UUCP (Doug Pardee)
Newsgroups: comp.sys.cbm,rec.music.synth
Subject: C-64 MIDI interface programming info
Message-ID: <882@edge.UUCP>
Date: Fri, 24-Jul-87 17:52:55 EDT
Article-I.D.: edge.882
Posted: Fri Jul 24 17:52:55 1987
Date-Received: Sun, 26-Jul-87 04:48:07 EDT
Organization: Edge Computer Corporation, Scottsdale, AZ
Lines: 17
Xref: mnetor comp.sys.cbm:589 rec.music.synth:1163

If anyone wants to program his C-64 MIDI interface, here are the basics...

A 6840 Programmable Timer Module is mapped at $DE00-$DE07.  It is driven
off of the CPU clock (1.02 MHz for US/Canada NTSC C-64s).  On those MIDI
interfaces with Tape-Sync output, it is driven by the 6840's "Timer 1".

A 6850 Asynchronous Communications Interface Adapter is mapped at $DE08-
$DE09.  It is driven by a 500 KHz clock.

Both devices are connected to the C-64's interrupt line.

The 6840 and 6850 are made by Motorola, Hitachi, Fairchild, I think
Signetics, and maybe other companies.  Data sheets are widely available.

I'll be glad to supply more details via E-mail.
-- 
Doug Pardee, Edge Computer Corp; ihnp4!mot!edge!doug, seismo!ism780c!edge!doug