Re: Need help identifying Sound Card

[mjmahon@aol.com (Michael J. Mahon)]

Joe asked:

>I finally got off my but and startign taking some pics of the hardware I'm
>trying to identify.
>These two pics are of the same sound card.  It has three GI AY-3-810 chips:
>
>http://home.comcast.net/~ikvsabre/AppleII/DSCN0201.JPG
>http://home.comcast.net/~ikvsabre/AppleII/DSCN0202.JPG
>
>
>Any idea as to the manufacturer and model?

No, but it is clearly a 9-tone + 3-noise channel sound synthesizer
card, with a 6522 VIA interface to the Apple II bus.  It is controlled
through the first 16 locations of I/O select space ($Cs00..$Cs0F),
which maps the 6522 registers.  (These 16 locations are aliased
throughout the $CsXX space, since it is incompletely decoded.)

The LS42 is a peculiar choice--a 4-bit to 10-line decoder--it might
be used to generate the selects for the 8910's, but it's hard to
tell without the backside traces.

6522 port A supplies the 8-bit data interface to the AY-3-8910's and
bits 0,1,4,and 5 (apparently) of port B are the control inputs to the
AY-3-8910's.

The chip manufacture codes cover a pretty wide range--from 1980
for the 6522 to 1988(?) for the LM741's--so the card may have
been manufactured as late as 1988 (or maybe someone just
replaced the 741's).

The 741's, BTW, indicate that the channels are grouped for
stereo line-level outputs (approx 1-2 volts).  It would be interesting
to know how an odd number of channels was grouped...

ISTR a 9-voice card around this time, for playing music, but can't
currently recall the manufacturer.  I recall seeing it advertised in
Byte magazine around the early 80's.

If you want to write software for this card, you'll need to look
up the datasheets for the 6522 and the AY-3-8910--both are
available on the web--and do a little more reverse-engineering
(aka: reenigne ;-) on the glue chips and their functions.

BTW, when taking pictures of cards, try to use a background
without detail, like a sheet of fine-grain paper, and, instead of
moving the camera off-axis to avoid reflections, move the light
off-axis.  This will keep everything in focus and the detail-free
background will shrink the .jpg files.