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Path: utzoo!utcsrgv!info-mac
From: info-mac@utcsrgv.UUCP (info-mac)
Newsgroups: ont.micro.mac
Subject: Macintosh Sound
Message-ID: <4886@utcsrgv.UUCP>
Date: Thu, 12-Jul-84 05:39:02 EDT
Article-I.D.: utcsrgv.4886
Posted: Thu Jul 12 05:39:02 1984
Date-Received: Thu, 12-Jul-84 16:01:56 EDT
Sender: peterr@utcsrgv.UUCP
Organization: CSRI, University of Toronto
Lines: 23

Date:     Wed, 11 Jul 84 10:42 PST
From: John Palevich <uw-beaver!palevich%atari.csnet@csnet-relay.arpa>
To: info-mac@sumex-aim.arpa
Subject:  Macintosh Sound

The sound is not sampled out of the horizontal deflection voltage.

The 8-bit value is actually loaded into a counter, where it counts down
during the horizontal line time, producing a variable duty-cycle
square wave.  This square wave is fed into an op-amp integrater to
produce a variable voltage, which is, in turn, amplified and fed into the
speaker.

I sent a message out about all this a long time ago.  I guess a bunch of
new people have joined the list since then. . . .


				Jack Palevich

[Ed. John's previous message on MACINTOSH sound is under
<INFO-MAC>MACINTOSH.SOUND at SUMEX, available via ANONYMOUS Ftp.]