Just a few notes about BASIC on the Living Computer Museum's CDC6500

ASCII Mode

  If you want access to the full ascii character set, issue the ASCII
  command before running BASIC. This is helpful if you want to use
  escape sequences for cursor movement in your programs.

MID$

  There is no MID$ command in the current version of BASIC on the CDC.
  Instead, use the SUBSTR command, which has the same format:

    10 A$="TEST"
    20 PRINT SUBSTR(A$,2,1)

    returns "E"