Commodore VIC-20: the first million

01What you'll learn

• What is inside the VIC-20: processor, memory, screen, sound, ports — with exact numbers.
• What the VIC chip could and could not do (no sprites, 16 colours).
• Why the cartridge port was key to the machine's success.
• How Commodore sold it: toy stores, William Shatner and a price under $300.
• How to set colour and sound from BASIC with POKE — and the most common mistake.
• How to run a VIC-20 today in the VICE emulator.

02Before you start

• No prior knowledge needed — knowing what a processor and RAM are is enough.
• Optional: a computer to run the VICE emulator 🔒 local (versions exist for Windows, Linux and macOS).
• Games and ROM files have owners. Use only those you are entitled to use.

03Steps

1. The machine at a glance

   The VIC-20 is an 8-bit home computer in a single case with a keyboard. Commodore made it cheap on purpose: Jack Tramiel wanted "computers for the masses, not the classes", and the product had three names — VIC-20 in the US, VC-20 in Germany (marketed as "VolksComputer") and VIC-1001 in Japan. Why it matters: a colour computer under $300, sold in toy and department stores — according to Wikipedia, the first computer sold in K-Mart.

   Parameter	VIC-20
   Announced	September 1980 (VIC-1001 in Japan — June 1980); in US shops from early 1981
   Processor	MOS 6502 · 1.02 MHz (NTSC) / 1.10 MHz (PAL)
   RAM	5 KB static; 3,583 bytes free for BASIC
   ROM	20 KB: 8 KB BASIC + 8 KB KERNAL + 4 KB character set
   Video	VIC chip (6560 for NTSC, 6561 for PAL) · 22 × 23 characters · 176 × 184 pixels · 16 colours
   Sound	3 square-wave generators + noise, mono
   Language	Commodore BASIC 2.0
   Ports	cartridge/expansion, cassette (Datassette), CBM serial bus (disk drives, printers), user port (RS-232), joystick (Atari-compatible), composite video output
   Price	$299.95 (historical price, 1981)

   💡

   Why "20"?

   It is often assumed that "20" is the screen width — it is actually 22 columns. The other theory is the total ROM size (20 KB). Bob Yannes says "20" meant nothing in particular: it was picked as a "friendly number", and the marketing slogan was "The Friendly Computer".

2. The VIC chip: what it could and could not do

   The VIC (Video Interface Chip) was designed by Al Charpentier in 1977 for cheap terminals and game consoles, but Commodore could not find a market for it. Robert Yannes revised it before mass production — taking a better sound generator from one unfinished chip and more colours from another. A single chip produces both picture and sound.

   Feature	Value	Note
   Colours	16	only 8 can be used for characters and the border; the rest are for the background and auxiliary colours
   Screen	22 × 23 characters · 176 × 184 pixels	lower resolution than the competition
   Sprites and bitmap	none	graphics are made with programmable characters
   Sound	3 square-wave generators + noise	one shared volume control
   Video output	composite	a sharper picture on a monitor; for a TV, an external RF modulator was included

   ✅

   Why static RAM

   Commodore had a surplus of static RAM chips, and Tramiel decided they should be used. That is why the board has no circuitry to refresh dynamic memory. With so little memory, the more expensive static RAM was acceptable — it uses less power, runs cooler and needs less support circuitry (Wikipedia).

3. Cartridges and memory expansion

   The cartridge port keeps the program in ROM — loading is instant, no tape needed. Commodore released cartridges for games and for memory: 3, 8 and 16 KB, for up to 27.5 KB for BASIC in total. The Super Expander cartridge adds BASIC graphics commands (up to 160 × 160 points). With 8 KB or more, the memory map is rearranged — which is why some programs only work with the exact amount of memory.

   📦

   The first five Scott Adams cartridges

   To have software from the start, Commodore ported five Scott Adams text adventures (Adventureland, Pirate Cove, Mission Impossible, Voodoo Castle, The Count) to 16 KB ROM cartridges. The first run brought over $1.5 million in sales. According to commodore.ca there were about 800 software titles for the machine.

4. Try it yourself: colour and sound from BASIC

   The VIC-20 has no dedicated colour or sound commands — you use POKE: writing a number to an address in the VIC chip's memory. The program below clears the screen, makes the background and border black, prints inverse text and plays three tones briefly.

   Commodore BASIC 2.0 · colour and sound (checked against the register documentation, not run)copy

   10 PRINT CHR$(147)
   20 POKE 36879,8
   30 POKE 36878,15
   40 PRINT CHR$(18);"INVERSE";CHR$(146);" NORMAL"
   50 POKE 36874,200:POKE 36875,215:POKE 36876,230
   60 FOR D=1 TO 500:NEXT D
   70 POKE 36874,0:POKE 36875,0:POKE 36876,0

   Line	What it does
   CHR$(147)	clears the screen
   POKE 36879,8	colour register: value = 16 × background + 8 + border (border colour 0–7). With 8: black background, black border
   POKE 36878,15	volume 0–15; without it there is no sound
   CHR$(18) / CHR$(146)	inverse text on / off
   POKE 36874…36876	three tone generators; they sound only for values 128–255; 0 stops them

   ⚠️

   Trap: a value below 128 is silent

   The old version of this lesson set the third voice to 100 — that makes no sound, because the top bit of the register is the "on" switch. The colour formula is derived from the register layout (background in the upper 4 bits, a normal/inverse bit, border in the lower 3).
   ⚠️

   Not tested live

   The program was checked against the register documentation but was not run in an emulator for this lesson — so there is no TESTED label.

5. The games

   Six titles with verified facts. Gorf and Omega Race are based on Bally arcade games — Bally licensed Commodore to make its arcade games into cartridges.

   Game	Year · team	What it is
   Gorf	1982 · Bally/Midway, publisher Commodore	A port of the arcade shooter; 8 KB cartridge. Reviewers note that the gameplay stays close to the original despite the limitations.
   Omega Race	1982 · Bally, publisher Commodore	A port of the arcade game; cartridge.
   Radar Rat Race	1981 · Commodore	An arcade-style maze game; Wikipedia's list marks it "aka Rally-X". Cartridge.
   Jupiter Lander	1981 · HAL Laboratory, publisher Commodore	A landing simulation on Jupiter: limited fuel, three landing sites, three difficulty levels. Often shown in ads.
   Sword of Fargoal	1982 · Jeff McCord, publisher Epyx	A roguelike dungeon game; released first for the VIC-20 (cassette and floppy), later for the C64. Based on his earlier game for the PET.
   The Count	1981 · Scott Adams, publisher Commodore	A text adventure (no graphics) on cartridge — one of Adams's five VIC-20 games.

6. How it was sold: "The Friendly Computer"

   The PET was sold through authorised dealers and had a "business" image. The VIC-20 went where the buyers were: toy and discount stores. According to Wikipedia it was the first computer sold in K-Mart. The face of the ads was actor William Shatner ("Captain Kirk") asking "Why buy just a video game?" and calling it "The Wonder Computer of the 1980s".

   Product manager Michael Tomczyk assembled a five-person team — the "VIC Commandos" — and insisted on "user-friendliness" as the prime directive, full-size keys and programmable function keys.

   📊

   The numbers we know

   The first computer to sell over 1 million units. The date of the millionth unit is not known; about 750,000 had shipped by the end of 1982 (commodore.ca). About 2.5 million in total by 1985. According to commodore.ca it was "the first colour computer" sold to the masses for under $300. Linus Torvalds received a VIC-20 at age 11 in 1981 and wrote first in BASIC, later in 6502 machine code.

7. Timeline: from the VIC-1001 to the end

   Date	Event
   June 1980	The VIC-1001 is announced in Japan (later renamed VIC-20 for the US).
   September 1980	Commodore announces the VIC-20.
   January–February 1981	The first units reach retailers. Price $299.95.
   1981	The VIC-1540 disk drive is released.
   August 1982	Commodore 64 — 64 KB RAM and the VIC-II chip. The VIC-20 keeps selling.
   End of 1982	About 750,000 VIC-20s shipped.
   1983	The "rainbow logo" version with the C64 keyboard appears; by mid-year the VIC-20 is widely available under $90.
   September 1984	The Canadian chain Canadian Tire advertises it at $80.
   January 1985	Commodore ends production. About 2.5 million units in total.

8. Try it yourself: the VIC-20 in an emulator

   The easiest path is VICE 🔒 local — a free emulator for Commodore 8-bit machines. The current version is 3.10 (24.12.2025); for the VIC-20 you use the xvic emulator. We describe the steps in general terms; we have not checked the menus live.

   1. Download VICE from its official site (see "Sources"); the GTK3 interface is recommended.
   2. Start xvic — you see the BASIC start screen (on an unexpanded machine: "3583 BYTES FREE").
   3. Type the program line by line and enter RUN.
   ⚠️

   Not tested live

   We did not run the emulator for this lesson. Follow the VICE manual for exact settings.
   ⛔

   Copyright

   Games and ROM files have owners. Do not upload or distribute other people's images.

04Check

Checklist

• I know the core numbers: 6502, 5 KB RAM (3,583 bytes free), 22 × 23 characters, 16 colours.
• I can explain why the cartridge port mattered.
• I can explain the "The Friendly Computer" strategy: toy stores, Shatner, a price under $300.
• I know the order of events: 1980 announced → 1981 in shops → August 1982 C64 → January 1985 end.
• I know that the sound registers need a value of 128 or more.

Quiz

05What's next

06Sources

1. Commodore VIC-20 (Wikipedia) — announcement, specification, memory, ports, ads, prices, sales.
2. MOS Technology VIC (Wikipedia) — colours, registers, sound, chip history.
3. List of VIC-20 games (Wikipedia) — years and publishers.
4. commodore.ca: VIC-20, the first computer to sell 1 million units 🌐 global — timeline, sales, prices, names in different countries.
5. C64-Wiki: VIC-20 🌐 global — colour and sound registers, start screen, cartridge list.
6. Commodore 64 (Wikipedia) — released August 1982.
7. Linus Torvalds (Wikipedia) — his first computer.
8. Games (Wikipedia): Gorf · Omega Race · Jupiter Lander · Sword of Fargoal · Adventureland.
9. PETSCII (Wikipedia) — character control codes.
10. VICE 🔒 local — official site, version 3.10 · manual: invoking the emulators.