6502 Assembly programming for the Commodore PET

The PET was the predecessor to the VIC 20, Released in 1976 it was the earliest of the Commodore home computers Later revisions added more memory and a higher screen resolution, though it was still only 'character based'

Pet 2001 / 3000 Pet 4000 SuperPet 9000 Cpu 1mhz 6502 1mhz 6502 1mhz 6502 + 1mhz 6809 Ram 4/8k + 8 /16k+ 96k Resolution 40 x 25 characters 1 characters set 80 x 25 characters 2 character sets 80 x 25 Characters 2 character sets Colors Green / Black Green / Black Green / Black Sound chip None / Beeper None / Beeper None / Beeper

Thanks to "KnightFire66" for the PET photos!

Memory Map

Character Map

Keymap

Rom Functions

I/O Map

Sound

The PET did not have any built in sound, but a speaker can be connected to the IO port.

The PET is capable of up to 4 octaves... one of 3 possible pairs can be selected with $E84A

Address $E84B will turn the sound on or off... we write #16 to turn it on, #0 to turn it off.
Address $E84A can be used to select the Octave with value 15/51/85
Address $E848 can be used to select the note, a value of 64-255 should be passed.

It is not possible to set the volume, or play multiple tones at the same time.

(Sound info taken from the PetFaq)

Sfx with Chibisound!