Another Mega Man 2 modification- I have questions on donors

[tepples]

That's odd. If Holy Diver Batman doesn't even give Morse code, then there's something seriously wrong with the wiring of A0-A11, D0-D7, or an enable. Are you sure you're using a correctly sized ROM image? (For example, use the 256 KiB image for a 27C020 or 29F020.) And are you stripping the iNES header correctly?

A blinking power light means a CIC bus fault. Black screen means a CPU bus fault.

[WReXx]

had the thought to try reading the chip with my programmer after a burn to compare, but it's not that. The burn is successful and verifies with the write buffer when I read. I'm not sure where to go from here. I am hesitant on tearing the socket out and soldering it directly in...

[WReXx]

That's odd. If Holy Diver Batman doesn't even give Morse code, then there's something seriously wrong with the wiring of A0-A11, D0-D7, or an enable. Are you sure you're using a correctly sized ROM image? (For example, use the 256 KiB image for a 27C020 or 29F020.) And are you stripping the iNES header correctly?

A blinking power light means a CIC bus fault. Black screen means a CPU bus fault.

I am using a 256kb ROM (mega man 2 is 256kb) on my AT29C020.
I am using TNINES to extract the PRG and remove the header.
I can try another program-- my size though is 262,144 bytes...

CPU bus fault, hmm. If just one of my addresses were incorrect it would still "work" right?
But if the chip isn't enabling... that's another story, right?

[tepples]

If just one of my addresses were incorrect it would still "work" right?

Any PRG ROM address line that's wired incorrectly can, and probably will, cause a black screen.

[Sverker]

This is why it is useful to keep a socketed board handy for testing your EPROMs out before committing them with solder.

[WReXx]

This is why it is useful to keep a socketed board handy for testing your EPROMs out before committing them with solder.

That was probably my next step- I wanted to do it all in one shot though

[WReXx]

Yeah this thing is fucked. I give up.

Soldered in a socket and connected everything as it should be for SNROM and it's still a black screen.

[WReXx]

I put the OEM chip back in and black screen...

obviously the problem is with the board. I checked the traces but no bueno.

I might as well start over. Sigh.

[AWal]

I wouldn't give up hope on this.

Two thing that stand out as I recently re-did this:

The socket has unconnected lines according to your pdf (neat btw; very very easy to read).

I'd start by tying Socket pins 1 and 31 to Vcc (+5V)...If the board had extra WRAM I'd say to bend a pin on the MMC1 up and go for SOROM, but that's no biggie...everyone has to start somewhere.

/OE is tied to ground...This could be problematic on 120ns+ devices as they might not get their code out in time (200ns never do unless you set them up this way). I'd personally recommend to lift socket pins 22 + 24 (/CE & /OE respectively), then solder Socket Pin 24 to PRG-ROM hole 22. Solder Socket Pin 22 to Vdd (GND). AM29F0x0-12 parts by datasheet will respond in 50ns max since it's active for the address changes...Only catch is that this drains an "Add-On" battery backup...which is not a problem here.


Once those changes are done get a continuity tester or ohmmeter out and check your PRG socket against the cart edge. This is the easiest way to figure out telltale connection problems. All data lines will show and most of the PRG-ROM should show up as well. Refer to the MMC1 Pinout on the Wiki for the few pins that don't go straight to the PRG-ROM.

Also check the pins as they are getting bent to fit the cart spacing. The one trouble with wires in that sort is that one macro in a cable can break everything.

Here's a current photo:


Both here are attempted SXROM. The top converted from an SNROM gone SOROM, the bottom starting as an SKROM. There's about a 2-3 year gap between these two, and it shows.

Good luck and happy burning