Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!samsung!interlan.InterLan.COM!interlan.interlan.com!yetsko
From: yetsko@interlan.interlan.com (Mike Yetsko)
Newsgroups: comp.sys.tandy
Subject: Re: SOUND OUTPUT FOR TANDY
Message-ID: <YETSKO.90Nov27081958@interlan.interlan.com>
Date: 27 Nov 90 13:19:58 GMT
References: <11569@j.cc.purdue.edu>
Reply-To: yetsko@interlan.interlan.com
Organization: Racal InterLan, Inc., Boxborough, MA (1-800-LAN-TALK)
Lines: 16
In-reply-to: zhou@brazil.psych.purdue.edu's message of 27 Nov 90 03:55:12 GMT

In the 1000 machines, there is the standard IBM type sound.  In addition, there
is the TI sound chip mapped to emulate what happend in the PC-jr with the
3-voice sound.  In the xL machines it went one step further.  The joystick
was digitized, and one of the side benefits was the fact that there is a 
D/A ramp that can be programmed for immediate voltages.  Since this is tied 
to the joystick comparitor, that is how Tandy does the A->D conversions of
voice and sound.  For playback, the same readings can be 'played back' 
and routed to the sound circuits.

I would suggest you get an SL or TL service manual if you want more info, 
or if you are just interested in the 3-voice sound, there are a number of
books that cover the PC-JR sound, and it applies to ALL 1000 type machines
from Tandy.

Mike Yetsko
	(formerly with Tandy)