The pump handed the engine one character and then waited a character time
before the next, on purpose, so it stayed behind the engine rather than ahead.
That leaves the engine with an empty buffer between every two characters of a
message, and an engine with an empty buffer transmits idle rather than waiting.
The idle is added to how long the message takes, which in a contest is time
paid for nothing.
The pump now keeps two characters in the engine: one being transmitted and one
behind it, so the engine never runs dry. The clock at the baud rate says when
the engine has room for the next one, and the engine reporting that it has
stopped transmitting sets the estimate back to an empty buffer.
The last two characters are now beyond reach rather than the last one. Everything
before them can still be rewritten, which is what the pane is for.
A message is finished when the buffer is empty and the engine is estimated to
have transmitted what it holds, so {END} and {RX} no longer run while the engine
still has the last characters of the message.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RtspmWmS7f8kUvcyaHpRWZ
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