Re: C64 ROMs on a MAX?

From: MagerValp (
Date: 2001-02-08 13:22:37

>>>>> "RDO" == Marcello 'R D O ' Magnifico <> writes:

BO> Some one has asked me to do a cartridge with 32K of RAM and the C64
BO> Kernal, BASIC ROMs for his MAX machine, on the assumption that, if
BO> it works in UMAX mode on the C64 it will work on the MAX machine (I
BO> don't have a MAX machine)

As long as mapping 32K of RAM in UltiMAX mode isn't a problem, I don't
see why. And as you said, it looks like all the necessary signals are

RDO> I doubt that a single cartridge could replace both high (Kernel)
RDO> and low (Basic) ROMs.

UltiMAX allows you to map external ROM at $a000 and $e000, effectively
replacing the basic and kernal.

BO> Can any one think of any pitfalls? eg the Kernal hangs 'cause it
BO> can't find a second CIA to intialize or something.

Shouldn't think so -- I think the reset routine only writes to $ddxx,
but it's been a while since I checked.

RDO> An only CIA? Sheesh... Well, if you can find an emulator and can
RDO> turn off a CIA, you can easily see if it works. I LOVE emulators
RDO> because they're great in doing this sort of things (and more)...
RDO> :-)

Taking the CIA out of the socket isn't too hard either, but you'll
have to ground VA14 and VA15 or you won't have any video.

    ___          .     .  .         .       . +  .         .      o   
  _|___|_   +   .  +     .     +         .   .  Per Olofsson, konstnär
    o-o    .      .     .   o         +
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