23 Feb
2017
23 Feb
'17
7:48 a.m.
On 2/23/17 8:25 AM, Bill Gunshannon wrote:
________________________________________
From: cctalk [cctalk-bounces at classiccmp.org] on behalf of Noel Chiappa [jnc at
mercury.lcs.mit.edu]
Sent: Wednesday, February 22, 2017 1:49 PM
To: cctalk at classiccmp.org
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: Q Bus Music Board
I have two of them and a RT-11 program in macro that can output tones
and clicks
music is just an extension of that.
To do music (or sounds with an D/A) card its a matter of moving a
sequence of bytes/words
in a regular periodic rate representing the voltage for instant of the
wave form.
For tones its a loop with values for amplitude, frequency, and wave shape.
For a simple output card its a matter of changing the state of a single
bit at the required rate
(flip it once every half millisecond and you get a 1khz tone).
If an PDP-8, 6502, 8080 and many others can do it a pdp-11 and any
output can.
Hell I've heard Line printers play music and asr33s rattling out a crude
version of
Jingle bells complete with bell!
Allison
From: Jim Stephens
That A6006 produces a hit in this document
...
AAV11-C ANALOG OUTPUT BOARD
...
4 DACs, and a DC-DC converter.
Sounds like it might be a standard analog output board, for lab settings.
I'll bet the music thing is some marketing ploy, like the card game in 'The
Story of Mel'. (What, you haven't read 'The Story of Mel'?!? :-)
Noel
________________________________________
I think IO have a couple of them but I never heard them play music. :-)
bill