Working on a replica of the ALF Products MC-16 card.
This is the original 1978 card, not the newer one with the programmable sound generator chip.
I'm having trouble finding a 1.782 Mhz crystal that drives the 8253 timer chip.
I could use a higher-frequency crystal, but would prefer not to.
The closest I've found so far is a 10.692 Mhz crystal from a surplus radio dealer (it's 6x the original frequency)
I could substitute something for the 4723 as long as it was functionally equivalent.
Have you tried Jameco Electronics?
https://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDisplay?langId=-1&storeId=10001&catalogId=10001
The 4723 can be replaced by a 74LS256. The 1782kHz quartz can be replaced by a clock-halved 3560kHz Quartz (2 flip-flops). The DAC can be replaced by a AM6070.
If you want to make some Boards ... i could use 6 or 7 bare PCB
Songs played with the MC1 ... not the same as the MC16, but nice too
-Jonas