Q Bus Music Board

[allison]

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
>
>      > 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

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


>