Editing BASIC-PLUS (section)

==Virtual machine==
BASIC-PLUS was not an interpreter but a [[compile and go system]]: each line of BASIC was translated into "PPCODE" (Push-Pop Code) as it was entered, for subsequent fast execution on its virtual machine. These translations did not tokenize the BASIC lines but rewrote them for use on a stack machine; you could not translate these representations back to BASIC statements. This avoided the need to repeatedly decode the keywords as strings: once converted to PPCODE the keywords were numbers that pointed to routines to run that function. BASIC-PLUS included a {{code|COMPILE}} command, but this was not a true compiler; this simply saved the program's PPCODE representation so that it did not have to be recompiled when the BASIC program was next loaded into memory. The system stored a user's program in two formats. One was the editable source code in text format, created using the {{code|SAVE}} command and normally placed in a .BAS file. The other was the PPCODE version of the program created by the {{code|COMPILE}} command and saved to a .BAC file; .BAC files were smaller and loaded and ran faster, but could not be edited.<ref>{{cite web | url=https://retrocomputing.stackexchange.com/questions/6468/basic-plus-inline-operators-do-they-actually-make-sense | title=BASIC-PLUS inline operators, do they actually make sense? |access-date=2020-08-05}}</ref>