RE: CommodoreWorld

From: MagerValp (
Date: 2004-07-03 20:17:06

>>>>> "RB" == Baltissen, GJPAA (Ruud) <> writes:

RB> But still I wonder if it could emulate a C64 at 2 MHz, 3 MHz or
RB> whatever clockspeed. In contrary to emulators, the VIC and SID are
RB> hardware. So if it takes this ASIC, let's say, 9 cycles to execute
RB> one 6502 cycle, we still have a C64 that can run at 3 MHz. Having
RB> extra registers to support the extra features, I can imagine some
RB> bits reserved for 'overclocking'.

RB> Per, you have a C-1, does it have a register for this?

Last I talked to Jeri about this (which was quite a while ago), she
had mapped the clock divider register in the $dxxx area. You could
program it to any frequency you wanted, including lethal ones. I
suggested that this kind of control was unnecessary, as there are only
two speeds that are useful - 1 MHz for compatibility or 20 MHz for
full speed.

RB> So the next time I'll edit my site, I'll add a text, on the
RB> mainpage, giving credit to all people and sites where I got my
RB> info from, OK? :)

Well, using that information without explicitly giving it credit is
OK, imho - it's there to be used and shared. The (potential) problem
with Tulip/Ironstone/C=2 is that they've benefitted from the infor-
mation and the availability of "abandoned" software, but now wants to
step in and control it. The C64 scene has always had its share of
illegal activity, and it's only in the last few years that it has
become completely open. To survive it would just go underground again,
but I think that this would be a loss for everyone. Having it all out
in the open creates many more opportunities for collaboration and
sharing of information.

There's a reason that the C64 is still very much alive, while other
platforms have faded away.

RB> Interesting news! This most probably means that this C64-DTV
RB> supports illegal opcodes as well.

That would be my guess as well. If you implement a 6502 core, you'll
end up with illegals more or less by accident. If your implementation
is close enough to the original, the illegals will work the same.

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

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