Commodore VIC-20 - when computers found their way home

The era of home computers began with a hobby project.

Commodore VIC-20 - when computers found their way home

The VIC-20 was the first home computer produced by Commodore.

The history of the VIC-20 begins in 1977, when MOS Technologies, already part of Commodore, developed the 6560 graphics chip (the PAL-6561 version was sold in Europe) called VIC (short for video interface chip). Soon the design process began at Commodore, or rather the search for a design for their first home computer, which was to be presented at CES in 1980. Jack Tramiel chose a hobby project, under the working name of Micro PET, developed in his spare time by MOS Technologies engineer Robert Yannes. The VIC-20 was the result of the decision to equip the Micro PET with a VIC chip. The VIC-20 inherited a lot from PET - it had the same processor, the same BASIC, and also supported the characteristic character set developed for PET, known as PETSCII. VIC-20’s cassette port and user port are compatible with these in PET. The disk drive port was new, VIC-20 had one joystick port (same as in Atari computers). The video port was also compatible with that of Atari computers. Four programmable function buttons have been added. An interesting fact is commodore-key - a key with the logo of the Commodore, probably inspired by the key with the Apple logo present in computers of this company.

The computer had 5 KB of memory, 3.5 KB of which was available to the user.

The VIC-20 operated in two modes, both essentially text modes, however one of them allowed you to define your own characters and could be used as an imitation of the graphics mode. Basic text mode allowed entering 22 columns and 23 lines of text. Eight text colours and eight background colours were also available to the user. In the second mode, the programmer could define his own characters with a size of 8x8 pixels using the general background colour and one foreground colour, or 8x4 pixels with two auxiliary colours.

The sound was also generated by the VIC chip. The user had four channels at his disposal - three square waves and one white noise.

Technical specifications:

CPU:6502 @ 1.1 MHz
Input/Output interface:VIA 6522 (one joystick port)
Sound:VIC (3 pulse wave generators and one white noise generator)
Memory:5 KB