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General Instruments AY sound chip interface?
Posted: Mon May 25, 2009 12:13 am
by JamesD
Did anyone introduce a Dragon interface for the General Instruments AY sound chip?
Re: General Instruments AY sound chip interface?
Posted: Tue May 26, 2009 8:24 am
by sixxie
Don't recall one.
I don't know about others, but at the time I was always a bit wary about add-ons like this though, assuming nobody would support them. I guess if everyone thinks like that it pretty much becomes self-fulfilling.
Re: General Instruments AY sound chip interface?
Posted: Tue May 26, 2009 6:58 pm
by jmk
The nearest I can think of is Jon Bird's add-on soundchip schematic:
SAA-1099 Schematic
I think he takes the stereo output to two headphone sockets, but the cartridge port does have a line marked "Ext Sound In" which may do what it actually suggests... Potentially it could be used for any mono soundchip (or any stereo one with the outputs mixed). AY... YM2413... SID...
Re: General Instruments AY sound chip interface?
Posted: Wed May 27, 2009 5:10 pm
by JamesD
jmk wrote:The nearest I can think of is Jon Bird's add-on soundchip schematic:
SAA-1099 Schematic
I think he takes the stereo output to two headphone sockets, but the cartridge port does have a line marked "Ext Sound In" which may do what it actually suggests... Potentially it could be used for any mono soundchip (or any stereo one with the outputs mixed). AY... YM2413... SID...
Ok, I knew I'd seen one somewhere but I didn't know is was for the SAA-1099. The SAA-1099 has 6 audio channels but they aren't has configurable as other sound chips, just square wave (I think the TI-99 sound chip was also just square wave but only 4 channel). It was in the Sam Coupe but not sure if any other 8 bit had it. It was on the soundblaster PC card but that also had the OPL2 which was much better and later sound plasters didn't automatically include the SAA-1099, they just had a socket for it.
The Ext Sound In does exactly what it says. The CoCo speech and sound pak uses it. One of the smarter things Tandy did when they made the CoCo. Too bad they waited so long to make something that used it and it was so expensive. A cheap, simple AY only solution probably would have fared better.
Re: General Instruments AY sound chip interface?
Posted: Fri May 29, 2009 10:59 pm
by prime
The Dragon Alpha also had one as standard (AY-3-8912), used it for sound and to control the drive selects on the disk interface.
It would be possible to add this to a Dragon 32/64, but would require socketing one of the PIAs, and adding a second, the AY
was connected to one of the ports on the 3rd PIA.
Cheers.
Phill.