An APRS Passcode Generator
Generates the APRS-IS passcode given a callsign or string containing valid APRS-IS login characters.
Unlike some online passcode generators, this version of the passcode generator will actually warn you if you attempt to use invalid characters or a login string length that would be rejected by the APRS-IS system.
Written in GW-BASIC: https://en.wikipedia.org/wiki/GW-BASIC
Will also run using PC-BASIC: http://robhagemans.github.io/pcbasic/
Can be easily ported to other languages.