Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!sgi!wdl1!bobw
From: bobw@wdl1.UUCP (Robert Lee Wilson Jr.)
Newsgroups: comp.arch
Subject: Re: Computer noises (was Re: Cray architecture)
Message-ID: <3490011@wdl1.UUCP>
Date: 15 Apr 88 00:02:48 GMT
References: <2516@umd5.umd.edu>
Lines: 33

I guess my age shows when I am surprised that playing music on a
computer is thought to be surprising! In addition to the radios
which I thought we all had used (most effective on core machines:
the fast, high current pulses could be accurately timed) the early
CDC machines had a built in console speaker. Current proportional to
the upper octal digit of the accumulator was sent through the voice
coil, and there was a volume control. In normal system operation you
got some idea of the kind of stuff going on: If there was a long
steady tone or no noise at all (i.e. the A register was not
changing) you assumed the machine was in a small tight loop, and the
system operator would take that as his cue to interrupt the program.
(Of course that was batch mode, and if your program did not get
interrupted it could wipe out your whole budget due to a programming
error!) Som of the diagnostics made use of the noises, or at least
the engineers new what noises to expect at certain times: The tape
drive diagnostic for the CDC 1604 was named Bagpipe, and sounded
like one in rhythm with the tapes sawing back and forth. By
intentionally juggling the A register you could program music or
other sounds. I had programs which composed music by the rules of
florid counterpoint, and whose output I have still heard only on the
console speaker. I had a quick console thumb-in which would let you
make race-car sounds, including braking and gear shifting, by
pushing the buttons under the A register display. At the Univ of
Wisconsin we kept a paper tape handy to play "On Wisconsin" for
visiting dignitaries. There was a rumor that CDC 3600's were shipped
out with "Oklahoma" for full chorus and orchestra in (non-volatile)
core, but since I can't imagine one coming up and running without
something trashing memory I don't know if anyone was able to test
it!
Regards,
Bob Wilson

(I don't even remember such opinions, much less attribute them to my
employer.)