The PET changed a lot across its life. Original BASIC 1.0 machines lack the standard $ff× jump table; the upgrade (BASIC 2.0) and BASIC 4.0 ROMs add it. BASIC 4.0 sits at $b000–$dfff; earlier ROMs put BASIC at $c000–$e7ff with a smaller map. 80-column models double the screen to $8000–$87cf and add a 6545 CRTC at $e880. See also the
VIC-20 and
C64 maps.