Re: Looking for ALF AM ][ disks images

[Phil Tubb <googleplus@w127.com>]

On Wednesday, May 2, 2012 8:16:59 PM UTC-7, Ralph wrote:
> ENTRY and PLAY are the old (DOS 3.2 or 3.3) programs that apparently
> 
> were used with the initial
> 
> ALF 3-voice cards - I'd expect these to be very different than the
> 
> ProDOS PLAY.SYSTEM.
> 
> 
> 
> There are two different ALF music synthesis cards, one is a three-
> 
> voice based on discrete logic plus
> 
> a 74LS624 VCO, an 8253 timer chip, four CD4723 chips, and 3 8227DP
> 
> chips
> 
> (I actually don't have a datasheet for the 8227DP- does anyone know
> 
> what function it performs?)
> 
> 
> 
> The nine-voice card uses the SN76489, a programmable sound generator
> 
> and a kind of a cousin to the AY-3-8910.
> 
> 
> 
> It would be an extreme coincidence if both synthesizers could use the
> 
> same software, since latches and registers
> 
> and a programmable time wouldn't present the same bus interface as the
> 
> SN76489
> 
> 
> 
> (I remember seeing an demo of the ALF card running on an Apple II at
> 
> "The Future Now", a computer store in Cincinnati.)

There are no 8227DP chips on the 3-channel ALF synthesizer (originally "Apple Music Synthesizer" and later "Music Card MC16").  There are three PMI DAC-76 chips http://www.chipsetc.com/pmi-precision-monolithics.html which are exponential D to A converters.

Phil