On 2/24/2017 1:04 AM, Daniel Kahlin wrote: > On Thu, 23 Feb 2017, Jim Brain wrote: > >> I know ROML and ROMH are only active on reads, except in Ultimax mode. >> >> My question is: >> >> Can anyone help with a small function that would take an address, a data >> value, a flag for the ROM area to write, and handle the heavy lifting > of: >> >> * switching to Ultimax mode >> * doing the write >> * switching out of Ultimax mode > > You cannot switch to Ultimax mode purely by software. The cartridge > needs > to provide some way to fiddle with EXROM & GAME. Understood. I forgot to mention that in my original post. > > Trivial example for Action Replay/Retro Replay: > > MODE_BITS equ %00100011 ; RAM + Ultimax > BANK0_BITS equ %00000000 > BANK1_BITS equ %00001000 > BANK2_BITS equ %00010000 > BANK3_BITS equ %00011000 > BANK4_BITS equ %10000000 > BANK5_BITS equ %10001000 > BANK6_BITS equ %10010000 > BANK7_BITS equ %10011000 > > ; Acc = data, Y = bank (0-7) > write byte: > sei > > ; optional to avoid visible glitches, wait until border area > ldx #$30 > lp: > cpx $d012 > bcc lp OK, I partially understand this. Is it because color ROM is no longer wired to anything? Because, I assume you could relo the screen RAM to somewhere in the first 4kB Jim Message was sent through the cbm-hackers mailing listReceived on 2017-02-25 04:00:02
Archive generated by hypermail 2.2.0.