>>> no, only on reads (except in ultimax mode). typically a cartridge >>> that >>> wants to map ram to these areas will reconstruct the CS signal >>> from the >>> adresslines and r/w. >> >> Well, and in Ultimax mode? > > i am not sure to be honest, ultimax is a bit "special" =) i *think* it > generates ROML/ROMH also for write accesses then. Some time ago I decoded the PLA equations from a PLA dump (not the one that is all over the web, because that one is corrupted). Ultimax mode, that is: not exrom and game: =================== 0000..0fff, cpu: ram 8000..9fff, cpu: cartridge low d000..dfff, (cpu read and ba) or cpu write: i/o d000..dfff, cpu read and not ba: ram e000..ffff, x1x, cpu: cartridge high e000..ffff, x0x, cpu: ram 3000..3fff, 7000..7fff, b000..bfff, f000..ffff, vic: cartridge high 0000..0fff, vic: ram 8000..9fff, vic: ram d000..efff, vic: ram rest open bus and the equations for #ROMH and #ROML are: .11..100..010... +.....+. .....100..0.10.. +.....+. port x11, addr 100x, cpu read, exrom addr 100x, cpu, no exrom and game --> cartridge low #CS ..1..101..0100.. +......+ .....111..0.10.. +......+ ..........1.1011 +......+ port x1x, addr 101x, cpu read, exrom and game port x1x, addr 111x, cpu, no exrom and game addr xx11, vic, no exrom and game --> cartridge high #CS So the only way to get #ROML for writes is in ultimax mode, addr 8000..9fff; and to get #ROMH for writes, you need ultimax mode, addr e000..ffff, and port 01 bit 1 high. Segher Message was sent through the cbm-hackers mailing listReceived on 2012-05-09 23:00:10
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