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I'm playing with MIT LOGO for the Apple II (1981). When I type TO GREET :NAME and hit ENTER it drops me into the "MIT LOGO screen editor." What are the commands I can use here to edit, save, etc.?

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This disk image is probably built from files/aplogo/logo.299 in the PDP-10/its-vault repo on GitHub.com, or very similar source. That same directory has a documentation file, usage.doc, but unfortunately that doesn't seem to document the screen editor commands. (It also seems to document a number of things not in that particular version of LOGO.)

The commands are dispatched from a table called EDSTBL, which contains the ASCII character to match followed by the routine to which to jump. They are as follows:

  • ^A: Go to beginning of line
  • ^B: Go back one screen
  • ^C: Complete edit (save and exit)
  • ^D: Delete char under cursor
  • ^E: Go to end of line
  • ^F: Go to next screen
  • ^G: Quit without saving
  • , ^H: Move back one character
  • ^K: Delete to end of line ("Kill")
  • ^L: Center current line on screen
  • ^M: Insert newline
  • ^N: Move down to next (logical) line
  • ^O: Insert a newline, leaving the cursor at the end of the existing line ("Open")
  • ^P: Move up to previous (logical) line
  • , ^U: Move forward one character
  • ESC, ^[: Delete previous character

Lines longer than 40 characters will be wrapped, with an exclamation point ! displayed at in column 40 of the screen for all screen lines but the last that are part of the logical line.

The RETRIEVE command from usage.doc, to re-enter a screen editor session abandoned with ^G, doesn't seem to exist in this version of LOGO, but EDIT (or ED) with no argument does the same thing.

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