Using AOROM to make a 2 in 1 multicart of NROM games

[Sivak]

Hey again. I finally took some time to look into this and I'm using the following method:

Basically, the code I copy to RAM are these instructions:

Code: Select all

.bank 3
.org $F000
LDA selectedBank
TAX
STA bankID, X
JMP $FFE0          ;$FFE0 is a spot of empty space in both games where I simply put the instruction JMP RESET, which is where the standard game reset routine is.

I just store the above code all at the beginning of $0600 and then JSR $0600. That works, but I just wanted to ask if that looked bug-free or if I might be missing something.

My question was regarding:

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.bank 3
.org $FFE0
;LDX #$00       ; you don't get a bus conflict if you
;STX RESET + 1  ; overwrite the immediate operand
JMP RESET      ;I guess I could also have done JMP $8000

When I have the LDX #0, and STX RESET + 1, that causes freezing and the games never load. But with those two lines commented out, the game loads fine. I also have both games' reset vectors point to a new routine (called RESET2) that simply forces bank 0 to be loaded and that works fine too.

So my question is: Are those two lines I've got commented out vital or is there no concern?

[Hamtaro126]

I wish someone made a 1-screen mirroring version of SMB1, That would really help

I attempted the above, But the code for the SMB1 renderer wasn't doing any of it right.

[Dwedit]

Or just abandon AOROM and use BxROM, GNROM or MMC1 instead.

[BMF54123]

I attempted the above, But the code for the SMB1 renderer wasn't doing any of it right.

Probably because it was never designed to work with one-screen mirroring.

[Celius]

Yeah, I'm pretty sure that SMB1 updates WAY off screen, so any attempt to do that with one screen mirroring will result in it updating right on screen.

[tepples]

Yeah, I'm pretty sure that SMB1 updates WAY off screen

So do a lot of vertically mirrored games, such as Contra.

I'm with Dwedit: just use BNROM. If you have a bunch of A*ROM boards, you can rewire them to BNROM by cutting the trace to CIRAM A10 and running a wire from CIRAM A10 to PPU A10 or PPU A11.