nesdev.org

Yep. And to think no emulator disables the WRAM bit....thats more headache for all those emu developers for someone to abuse that for something amazing.


But I am guessing that only 1 CHR-ROM line will be connected and the rest just grounded or whatever? a ground pulls low, right? Or is it floating?


What pins on the MMC1 do you want me to test exactly?


And like I asked before, how much do revision numbers matter in the wiring of the cart?

You should check pins 9-11, especially pin 11. Pins 9 and 10 (A14 and A15) very likely go to pins on the CHR-ROM, that are unused by DW, but are here for support up to 64kb CHR-ROM.

Pin 11 (A16) however, is what I'd want you to look where it leads... On MMC1 boards with 128kb CHR-ROM this is A16, on SUROM it is the main 256k page switch and on SNROM it is a second WRAM enable.... so I'm very curious about if it is used on SAROM.

I don't think revisions matters in any way, usually they just changed the layout of the traces and componant, not the shematics. The only place I remember they changed something on the same board was that they added a capactiy on SNROM-04 and + to make saves more reliable than SNROM-03 and -

a ground pulls low, right? Or is it floating?

Ground pulls low, and unconnected is floating. Unused inputs are usually pulled low or high (ground or VCC respecively), while unused outputs should be left floating.

EDIT / PS : The fact that A16 was sometimes connected to WRAM /CE was already doccumented, at least from Kevtirs's site, and even the nesdev wiki. It's just that nobody really noticed it.

Okay will do. I'll edit this post with the trace findings in a couple hours if I don't fall asleep.


UPDATE:

(MMC1 Pin)-(Where)
A12-Pin 2 on CHR-ROM
A13-Pin 26 on CHR-ROM
A14-Pin 27 on CHR-ROM
A14-Pin 1 on CHR-ROM
A16-Seems to go nowhere.


It seems that these are all the right pins by looking at the MASK ROM pinouts on the sheet.....do I pass?


EDIT AGAIN:

Just opened up my Zelda 2 cart and tested A16, It does go to the SRAM pin 20 for enabling. Well, since I am figuring this junk out, time to attempt to make a SUROM board....if I can find the parts.

So yeah, A16 is usunsed and doesn't go to the WRAM enable. That's all I wanted to know, thank you very much.

EDIT : Oh and does anyone have a SJROM board ? Like SAROM, the upper CHR line is unused, and could potentially be used for WRAM enable. Although if it's not on SAROM I doubt it is on SJROM but who knowns.

EDIT 2 : Never mind I checked bootgod database, and the A16 line isn't connected on SJROM.

I'll double check that sometime just to make sure. I have Miracle Piano somewhere, too bad not the Piano.


And on the DW board, the pins that weren't used went off the board directly to the left of the chip looking at it from the 1 pin on the top left, so if you look at pictures, you might be able to see what is used and what is not easily.