I know of no BASIC extension that comes on plug-in ROM for the C64 (no space left on the original ROM for any enhancements). Thus, all the BASIC extensions came on cartridge or on disk. A nearly complete listing of the extensions is at
http://www.npsnet.com/danf/cbm/languages.html#BASIC-extendersThe list does not seem to include BASIC 4.0 which was in the Better Working Turbo Load 'N Save cartridge nor the BASIC 4.5 which was in RUN magazine issues 18-20.
Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug