The display has a third use: serial error annunciator. $D5F2 renders
'E0' + three live counters (TX-ring overflow $3187, reply retries
$3184, give-up teardowns $3185); $DAB8/$DAB2 is a terminal crash
screen spelling 'dEAd' when the TX dispatcher meets an unknown command
byte. Also recorded: RX overrun is unhandled (checksum NAKs are the only
symptom), unused vectors hang in BRA-self stubs, FAULT LED = MAX690 PFO,
manual/remote reset works by pulling PFI low, RUN LED = buffered AS*,
and the MAX690 watchdog is unconnected/unserviced — software wedges
persist until reset, matching bench observations.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
CydandClaude Fable 5
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