I have a PDP-11/53 and have just started playing with an AAV11-C D/A
board. It is a 4 channel D/A convertor with 12 bit resolution.
Can it be used to play an audio bit stream?
Here is simple code used to see if the thing was actually working:
.title AAV11 D/A test
;
.asect
dbr0 = 170440
.=1000
start:
mov #7777,r0 4096 value to R0
mov #dbr0,r1 first D/A buffer out
loop: mov r0,(r1) transfer value in r0 to D/A out
dec r0 subtract 1 from D/A value
bne loop
br start loop back to start
I was surprised to see that it took ~34 ms to run through all the
numbers from 0-7777, that is about 34 Hz. The manual says the 'settling
time' is 6 microseconds. Is this fast enough for audio?
How would you convert a modern audio file into 12 bit integers?
Doug
