--- Ruud Baltissen <Ruud.Baltissen@abp.nl> wrote:
> Hallo Marko,
>
> > Has anyone made any experiments with overclocking NMOS chips?
>
> No, but with underclocking. The 6502 runs at 500 KHz but dies at 250 KHz.
> What is the explanation?
Internal capacitors probably discharging before the next clock cycle hits,
like if you miss a refresh cycle on a DRAM. Not all processor designs
are stable at near-DC clock-rates. The 1802 is. A friend of mine was
debugging his Elf with a debounced switch and a volt meter because he
didn't have an oscilloscope when he was 16. It works. Several seconds
per clock tick, 8 ticks per cycle, 2 or 3 cycles per instruction.
Could be some sort of R-C driving a flip-flop as part of the state machine
for the processor states or something similar. I doubt the registers are
dyanamic, but they could be - it would reduce the part count.
Anyone have any internals knowledge?
-ethan
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