I oppened CastleVania (UNROM-07), Metal Gear (UNROM-08) and Skate or Die (UNROM-09). All of them had 28-pins EPROM and no holes for 32-pins EPROM.
The only differense that were is that UNROM-07 had all connecor pins present, even if not used, and that it was written "LS-32" and "LS-161", while UNROM-08 and UNROM-09 had "HC-32" and "HC-161" written on them. However, CastleVania had HC chips even if it is written LS on the board. I think LS chips would render less reliable voltage in their outputs, but they would be faster (delay is 8ns instad of 15, I did that at scrool :wink: )
An alternative would be to burn it on a SGROM board with a MMC1... It would need few software modifiactions, and SGROM has room for 32 pins chips, and is perfectly compatible with UNROM, as well than ANROM, AOROM, BNROM, and UOROM. Only the software should have a few modifications. For example, to burn a UNROM board on a SGROM card :
Instead of :
Code:
lda #Banknumber
tay
sta BusCfxTable,Y ;Write bankswitching to the mapper
There should be once at reset :
Code:
lda #$80
sta $9ffff
.if Mirroring="horizontal"
lda #$0f ;Put MMC1 in UNROM emulation mode :
.else ;16kb LOW aera switching, 8kb CHRAM, vertical/horizontal mirroring
lda #$0e
.endif
sta $9fff
lsr A
sta $9fff
lsr A
sta $9fff
lsr A
sta $9fff
lda #$80
sta $bfff
ldx #$05
lda #$00
- sta $bfff ;Reset both CHR ports, to be sure that there is no problem
dex
bne -
lda #$80
sta $dfff
ldx #$05
lda #$00
sta $dfff
dex
bne -
rts
Then, when it's time to bankswitch :
Code:
lda #BanswitchNmr
sta $ffff
lsr A
sta $ffff
lsr A
sta $ffff
lsr A
sta $ffff
lsr A
sta $ffff
rts
It's not a lot of modifications, but it would just need some room in PRG ROM.
AOROM would be compatible as well, but writing to $9fff would be needed to each bankswitching, because the single screen selection is merged with the rombank swlection. Also, the MMC1 should be set in 32kb bankswitching mode.
CNROM and GNROM are also emulatble as well, with a SLROM MMC1 board with CHRAM.