Reverse Engineering the CIC
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To dregde this thread up from the pits of the forum:
I just recenly came upon another cpu architecture which could be the one used on the original CIC: The NEC ucom-43 architecture, as used on the uPD650 (used in several classic roland products like the tb303)
Datasheets are available describing the instruction set and chips at http://www.teaser.fr/~amajorel/nec1981/
I know the NES CIC FUNTIONALLY is known what it does, but the actual original cpu is still unknown, and is needed if we ever want to reverse engineer the snes and n64 CICs, both of which also use it.
Hopefully we can finally figure out the 4-bit cpu type thats used.
LN
I just recenly came upon another cpu architecture which could be the one used on the original CIC: The NEC ucom-43 architecture, as used on the uPD650 (used in several classic roland products like the tb303)
Datasheets are available describing the instruction set and chips at http://www.teaser.fr/~amajorel/nec1981/
I know the NES CIC FUNTIONALLY is known what it does, but the actual original cpu is still unknown, and is needed if we ever want to reverse engineer the snes and n64 CICs, both of which also use it.
Hopefully we can finally figure out the 4-bit cpu type thats used.
LN
"When life gives you zombies... *CHA-CHIK!* ...you make zombie-ade!"
This doesn't help any of the RE work, but interesting that the SNES CIC uses the same "select 1 of 16 streams" that the NES CIC does. It comes much later after reset. The data is also similarly sparse.
NES stream select: http://www.nesmuseum.com/10nes/10nes%20 ... 0pulse.png
SNES stream select: http://www.nesmuseum.com/10nes/snes1111.png
NES stream select: http://www.nesmuseum.com/10nes/10nes%20 ... 0pulse.png
SNES stream select: http://www.nesmuseum.com/10nes/snes1111.png