On 07/23/2016 09:42 PM, Segher Boessenkool wrote: > 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 :-) Which reminds me... we still don't have a die pic of a 8360R2... I only have a moderatly good one of the 8360R1. > >>> 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. I would assume like a 6510, just smaller since it's no longer NMOS but HMOS-II. I really doubt they made more changes than they really had to. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2016-07-23 21:00:02
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