Re: VIC 26 Lines Bug - Truth or Legend ?

From: Ethan Dicks (
Date: 2001-08-21 19:36:12

--- Ruud Baltissen <> 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?


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