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Path: utzoo!linus!decvax!harpo!seismo!hao!hplabs!sri-unix!GUBBINS@RADC-TOPS20.ARPA
From: GUBBINS@RADC-TOPS20.ARPA
Newsgroups: net.micro
Subject: DRC Sound board S-100
Message-ID: <16762@sri-arpa.UUCP>
Date: Tue, 14-Feb-84 09:26:27 EST
Article-I.D.: sri-arpa.16762
Posted: Tue Feb 14 09:26:27 1984
Date-Received: Tue, 21-Feb-84 03:49:07 EST
Lines: 28

From:  Gern 


Russ (and All),

I looked over the DRC stuff you send Wolf.  Thanx much.  My previous
concerns/guesses were correct.   DRC is no longer selling the board.
The device completely violates the IEEE-696 S-100 standard for bus
line loading.   To correct this would lead to a major redesign, hence
they probably choose to just drop the product.  The maximum the
device can be driven at is 4MHz and it inserts 2 I/O wait states to
do just that.   My design is radically different and can work in a
5 MHz Z-100 without adding any I/O waits (Do note that the Z-100
does add one on its own).  The DRC board would not work in my
Z-100, so my design approach is the only way for me.

This week I am going to see if I can extend my design to double
that of the current 3 voice, 2 I/O design and not violate anything,
or screw up the timming.  I think I can do it and use 3 less ICs!!!
And I will be able to play all of the piano sheet music to Star Wars
Main Theme (requires 5 channels), I currently had to drop the
Bass Clef notes - still sounds excellent.   I'm going to take your 
suggestion and drop the I/O multiplexing which will yield a cleaner
more uselful device.

Cheers,
Gern
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