Are tatty boxes worth keeping?

From: Doug Coward <>
Date: Tue Aug 10 15:03:19 1999

Various people said:
>> > The Commodore 64 _could_ run CP/M programs...provided one had the
>> > optional Z80 cartridge...though I never tried myself. :-) The 128 was the
>> > first Commodore machine to actually boot CP/M disks with a 1571 drive,
if I
>> > remember correctly.
>> Well so _could_ the PDP-8 if someone built the necessary hardware or wrote
>> a simulator for it :)
>And so can a Macintosh if you run a terminal emulator and connect the
>serial port to a Northstar Horizon. :-)

  I point is that Commodore had the foresight to put a "DMA" line
on the Expansion Port so that an external device could tri-state
the address lines on the 6510, effectively removing the 6510 from
the memory map. Which makes it very easy to run the C64 with multiple
processors or just a different processor.
 The C64 CP/M cartridge was set-up so that you could have 6502 code
embedded in your Z80 code. You just need to set a certain register
every time you wanted to switch processors.
 That coupled with the fact that you could swap out all the ROM and
all of the I/O leaving a continue 64K ram space, makes the C64 a
hardware hacker's dream.
 Just my two cents.

Doug Coward (work)
Sr Software Engineer (home)
Press Start Inc.

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Received on Tue Aug 10 1999 - 15:03:19 BST

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