The SNES Chip compatible with NES?

[CNadolski]

I'm finding more info about the SNES, and found some information about its CPU:
http://www.zophar.net/tech/files/65816info.txt

Apparently, it's 100% emulation compatible with the chip that runs the NES.  Could the SNES therefore accept NES cartridges (in theory, if the hardware were there)

Just something to mull over.

[RobIvy64]

The SNES is largely similar to the NES.

In fact, the system runs at 1.79 MHz when reading from the ROM, or when it is booting, and it runs on an 8-bit bus.

If you try it yourself make sure you don't overclock the two PPUs. This will send the hertz-rate through the roof and fry any TV you hook it to.

rob

[RobIvy64]

Another thing:

The CPU is a hacked version of a 65c816.....a VERY hacked version. It contains some Nintendo video hardware.

If you look at the CPU there are 100 pins as oposed to a stock 65c816's 40.

Unfortunately pinouts dont seem to exist since it is such a customized CPU.

[Guest]

Actually, I'm looking at the SNES pinouts right now.  You'll never guess where I got it: it's from the NES modding group on yahoo.com (can't remember which post it was).  If you look at the files section, you can download a set of gifs which are "Schematic Diagrams for Super Nintendo Entertainment System".

Granted, they don't tell you what all of the pins do, but it helps.

Back to the overclocking question... How do you overclock the SNES if it uses multiple clock speeds?  Can you say, give the clk signal on the CPU a 7.16 MHz oscillator and hope it all works out?

The clock shown in the diagrams comes out of a chip callled "D214GO" (couldn't find it with google) surrounded by a bunch of capacitors, resistors, and transistors.  Seems like it could be replaced by a common 555 timer, or a quartz crystal.

[CNadolski]

that was me by the way.

[RobIvy64]

If you have AOL my scr name is ROBISABIGMAN
It would be easier to explain

rob

[Guest]

Even if the cpu runs the same instructions, I would imagine the ppu would be a problem. Also, the snes has a different lockout chip then the nes. Try looking at a "super 8", which was an adaptor, and see what it does.