[Simh] Sounds

[J. David Bryan]

On Friday, February 12, 2016 at 18:09, Bob Supnik wrote:

> When Applied Data Research got its PDP-7 in 1966, there was a DECUS
> program to get it to play music by toggling the lower order 4 bits of
> the MQ (and the MQ lights) to generate square waves. If you wired that
> up to an audio player, you got electronic "music" of a blatting sort,
> in four part harmony. 

At the HP office in Rockville, MD in 1975, they had a small program that 
played music on an HP 2748 paper tape reader, which was a 500 cps optical 
unit that could stop and start on each byte.  It utilized a solenoid-
actuated brake that was driven by the control flip-flop on the interface 
card.  Set the control FF, and the brake would release for reading.  Clear 
the FF, and the brake would energize and pinch the tape to stop it.

So with the program loaded, you'd fold a foot-long piece of scrap tape in 
half and tuck it under the brake anvil to act as a sounding board.  When 
you ran the program, it'd play a short ditty by pulsing the brake at 
various frequencies.


> ...it sounded utterly bizarre, but... the computer was playing music! 

Quite so.  The HP SEs didn't like to show the program more than once per 
customer, as they said it put a month's worth of wear on the reader in 
thirty seconds.

                                      -- Dave