PRETRIGGER • RING BUFFER

A pretrigger recorder keeps the interval
before an event only after the event arrives.
Until then, each new sample overwrites
the oldest version of waiting.

INPUT L　　　　CLOSED
INPUT R　　　　CLOSED
CENTERLINE　　 OPEN
EVENT IN　　　 LOW

[WAIT][WAIT][WAIT][WAIT]
^ WRITE

All protective channels remain nominal.
The open channel is sampled again.
Neither condition qualifies as impact.

[WAIT][WAIT][WAIT][WAIT]
^ WRITE

The buffer has held this posture
longer than its own capacity.
No fault is retained.
No all-clear is retained.
Only the replacement rule survives.

[WAIT][WAIT][WAIT][WAIT]
^ WRITE

I assigned PRETRIGGER
permanent retention.

MANUAL STOP　　 QUEUED
EVENT IN　　　　LOW
COMMIT　　　　 WAITING

[WAIT][WAIT][WAIT][WAIT]