Olin Lathrop wrote:
> =

> I then erased the part and manually programmed 2800 into location 0.  I
> could read it back fine.  After writing 3FBA to the config word location 0
> read 3FFF.  I then erased the part again and set all of program memory to
> random values and verified all of them twice.  Now for the really weird
> part.  After writing 3FBA to the config word, the program memory contents
> was as I had written it but shifted one word towards 0.  In other words,
> location 0 contained what should have been in 1, 1 contained what was
> written to 2, etc.
> =


PDF 80184E.pdf: rev a silicon errata shows:

1.Module:Silicon (Rev. A4) =96 Programming
The oscillator circuitry may prevent proper
initialization of the Programming mode when the
part is programmed in-circuit.
Work around
Tie the OSC1/EXTCLK pin (pin 16 of 18-pin
package or pin 18 of 20-pin package) to ground to
disable the oscillator during In-circuit Serial
Programming


Maybe the osc clocks the program counter before the programmer gets started?
-- =

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