Re: FPGATED

On Saturday 23 July 2016, 21:16:18 Gerrit Heitsch <gerrit@laosinh.s.bawue.de> 
wrote:
> On 07/23/2016 09:08 PM, Segher Boessenkool wrote:
> > On Sat, Jul 23, 2016 at 08:46:04PM +0200, Gerrit Heitsch wrote:
> >> On 07/23/2016 08:22 PM, Segher Boessenkool wrote:
> >>> On Sat, Jul 23, 2016 at 06:29:33PM +0200, Michał Pleban wrote:
> >>>>> Next project would be a replacement 8501 since those also die
> >>>>> easily...
> >>>> 
> >>>> That should be much easier, as no analog stuff (video) is needed and a
> >>>> 6502 core is easily obtainable... Somebody should really make such
> >>>> project :-)
> >>> 
> >>> 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.
> 
> > 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.

see https://sourceforge.net/p/vice-emu/code/HEAD/tree/testprogs/CPU/cpuport/

... there is another testprog in the repo which tries to determine the type of 
CPU by checking the cpu port - however that one does NOT work correctly:

https://sourceforge.net/p/vice-emu/code/HEAD/tree/testprogs/CPU/cputest.txt

(corrections/improvements welcome)

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