I/O chip for Bally Astrocade?

[Josh Dersch]

John Robertson wrote:
> Josh Dersch wrote:
>> Ok, so it's stretching the definition of "computer" but it _does_ 
>> have a BASIC programming cartridge and it IS classic (1978) so I 
>> think it qualifies...  Got me a Bally Astrocade that appears to have 
>> a dead I/O chip.  From the service manual, this is a custom chip 
>> listed as PN "0066-117XX-XXYX"... I figure it's a long shot, but 
>> anyone out there have spare parts for these?  I figure if anyone 
>> knows, they're on this list :).
>>
> If the CPU is a Z80, then the I/O is likely to be a 8255, if the CPU 
> is a 68XX then the I/O is likely a 6821, and if the CPU is a 6502, 
> then the I/O is likely either a 6520, 6821, or 6532. Check how the 
> power pins to it compare to those common I/O chips of the day.
>

Thanks.  The Astrocade's Z80-based.  The I/O chip does not look like an 
8255 based on the pinouts.  (Plus, it's got inputs for analog joystick 
stuff as well.)  The schematic calls out several chips as "Custom" along 
with the more standard parts (like the CPU and various bits of TTL glue) 
so I'm guessing the I/O chip is not an off-the-shelf part.  (Alas.)  I 
guess I'll just have to keep my eyes open for spares...

Thanks,
Josh

> John :-#)#
>
>