This Morse Code Encoder/Decoder would buffer both send and received data and display the size of the queues as a bar-graph in the computer's lights.
I coded in pdp-8 assembly language. I prepared paper-tape binaries which I brought to Jim Wilson's apartment for testing. Development progressed over a number of weeks as evidenced by the revision history in the header comments.
/ MORSE CODE TRANCEIVING PROGRAM / COPYRIGHT HOWARD G. CUNNINGHAM 02/18/75 / REVISIONS: / 02/18 TRANSMIT / 02/24 BUFFERED I/O / 03/06 RECEIVE / 03/18 RUBOUT AND ERROR CODE
Full source code 
is available.
The program seemed simple enough that there was no written documentation other than a summary of control keys that one could type in addition to letters to be sent.
PDP-8 MORSE KEYBOARD COMMAND SUMMARY
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MORSE CHARACTERS:
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A-Z SEND LETTER
0-9 SEND NUMBER
,./? SEND PUNCTUATION
SPACE PAUSE FOR WORD SPACE
# SEND AS (.-...)
$ SEND AR (.-.-.)
& SEND SK (...-.-)
" SEND ERROR CODE (........)
TRANSMIT BUFFER EDITING:
------------------------
^E ERASE ALL CHARACTERS IN BUFFER
RUBOUT ERASE PREVIOUS WORD IN BUFFER OR SEND ERROR CODE
SPEED CONTROL:
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^F SEND 25 PERCENT FASTER
^S SEND 25 PERCENT SLOWER
INPUT PRINTBACK CONTROL:
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^I ECHO CHARACTER WHEN INPUT (TYPED)
^O ECHO CHARACTER WHEN OUTPUT (SENT)
^N DO NOT ECHO CHARACTERS
^M LOCAL RETURN TO LEFT MARGIN (CR-LF)
RETURN SAME AS ^M
OPERATION MODE CONTROL:
-----------------------
^T TRANSMIT (IGNORE RECEIVER)
^R RECEIVE (BUFFER KEYBOARD INPUT)
^X TRANSCIEVE
^D DUPLEX