BlackMark 2655d058f4 pbhw: an absent probe is not a destroyed loader ...

The slot-survives-erase check reads back over ISP by design — an independent
reader is the only witness worth having about a loader that has just been
asked to erase around itself. With the one probe on another board it printed
"ISP read failed" as a red, which is the same word a destroyed loader would
get, and it is permanently red on the two deployments with no ISP header at
all.

It names its witness now and falls back to the link when there is no
programmer, saying that the loader is then reporting on its own slot — weaker
for exactly the reason it is worth having, since a destroyed loader could not
answer at all. An absent instrument is a fact about the bench and a wrong byte
is a verdict on the subject; a check that prints them identically stops being
read.

Both paths exercised on hardware: ISP on the Uno, the link on the ATtiny13A.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

2026-08-01 20:25:47 +02:00

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