squall926 wrote:
What are the visible differences between an arduino and snes? speed only? It's possible 74ahc245(5 to 3,3v addr line) or LJ245A(3,3 to 5v data line) no
fast enough?
The big differences that occur to me are:
* Yes, that; the speed through the 5->3 downtranslation, the PSRAM itself, and the 3->5 uptranslation
* Voltage thresholds (I think the arduino uses 5VTTL levels, while the SNES uses 5VCMOS levels)
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The VCC is about 4,8v but if snes can read some cart with flash 3,3(lol) i believe it's no problem.
If the signals actually get all the way up to 4.8V, that's fine.
The SNES does
not run reliably on 3.3VCMOS levels. There are reports of random crashes due to a nonzero error rate (1e-6? 1e-9?) incorrectly receiving a 0 instead of a 1.
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Now i unmounted the cart, will remove the MAD and wire entire bus to PSRAM without sram from original cart and try run a small rom like u say.
I was just thinking that you could try putting one of the small ROMs in the PSRAM. The small ones should let you figure out if it's a problem with the higher address lines or not.
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If i put a 4MB CHIP on snes bus with a small rom writed snes keep unused address(high address like A19, A20, A21 and A22) pins in low?
The SNES boots by reading a 16-bit address from $00FFFC. That code then usually switches into 65816 "native" mode and does a little more. Variations in boards change how ROM A15 and up are wired, which is why I was suggesting something tiny.