On Sat, Jul 23, 2016 at 09:16:18PM +0200, Gerrit Heitsch wrote: > >>>The visual6502 project has a die picture of an 8501. From the picture > >>>it seems clear that both the 8500 (c64c) and 8502 (c128) used the same > >>>silicon, with different contacts bonded out. > >> > >>You sure? The 8501 is missing Port-Bit 5. It's not only not bonded out, > >>it's not present, you can't set it while the 8500 has all the port bits, > >>you can set them. > > > >(bit 5? Do you mean bit 7?) > > No, the 8501 is missing Bit 5, Bit 6 and 7 are present and used. They > are used as inputs from the IEC bus. I assume since that makes is easy > to use the BIT command or ROL/ASL for serial/parallel conversion. Ah, yes, I should look more carefully at the die pic :-) > >Why do you think you can set all port bits on the 8500? > > Because people have been trying to use Bit 6 and 7 to determine CPU > temperature or detecting a 6510 or 8500 from the time it takes a 1 to > become a 0 when switching the port from output to input. It will be interesting to see what 8500 looks like, then. Segher Message was sent through the cbm-hackers mailing listReceived on 2016-07-23 20:01:02
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