The Commodore Vic-20 Computer

Commodore’s Vic-20 was the first personal computer to sell one million units. It was officially launched in the middle of 1980 at $299. The price of a new Vic-20 would eventually drop to as little as $99. This was extraordinarily inexpensive for a color computer at that time. During it’s production life (of approximately 4 years) the Vic-20 would go on to sell more than 2.5 million units in total. At one point they were being produced at a rate of more than 9,000 computers per day.

Commodore designed the Vic-20 around the VIC (Video Interface Chip). They built the VIC with the intention of using it in the video game market — but they later decided to re-purpose the VIC for a new affordable home computer.

“You are about to meet a friendly computer! Friendly in price, friendly in size, friendly to use and learn on and experience. Most important — you don’t have to be a computer programmer, or even a typist, to use it!” — Personal Computing on the Vic-20, a friendly computer guide

Having their own chip manufacturing facility (MOS Technology) allowed Commodore to build many of their own components. This was a distinct advantage over many of the other computer manufacturers at that time. Commodore had a surplus of 1K chips and so these were used in the Vic-20 to save on production costs. The Vic ultimately became a computer that people wanted and purchased as quickly as they were being produced.

Commodore Vic 20

The Vic-20 was designed to play video games and compete with Atari’s 2600. However, the Vic was advertised as being more than just a video game.

Despite some of the relative shortcomings the Vic had when compared to more powerful and expensive computers, it was a fully functional and affordable computer. You could not purchase a computer with as many features as the Vic-20 for anywhere near it’s sticker price.

Before the Vic arrived, Commodore had been selling Personal Electronic Transactors (PETs) and calculators. The Vic shares many things in common with the PET computers that preceded it but was smaller and more affordable.

“When you first considered buying a computer, the chances are you said something like “I know computers are good things to have and it’s nice that they’re finally affordable, but … what can I do with one?” The great things about a computer is that you can tailor the machine to do what you want it to” — VIC-20 Programmer’s Reference Guide

Vic 20 Keyboard

The full stroke typewriter-style keyboard of the Vic-20 had graphical symbols displayed on the front side of the keys for quick and easy reference. Atari would later do this to the keyboards on their XE line of computers.

Overshadowed by the 64

The Vic-20 has to some degree been in the shadow of the single most successful personal computer of all time : The Commodore 64. Released only two years after the Vic-20, the Commodore 64 likely accounted for the rapid decline of the Vic-20 more than any other single factor. The 64 was viewed as the next greatest thing while the Vic-20 was becoming obsolete.

The 64 had a 40 column higher resolution display, came with 64K of RAM, supported hardware sprites and had a 3 voice synthesizer-style sound chip. It was designed to use the Vic-20’s peripherals to a certain extent such that when you outgrew your Vic-20 you could bring many items over to use with the 64.


With 3.5K available in BASIC in an unexpanded system, the Vic’s weakest point was how little RAM the computer had built-in. Thankfully, the Vic-20 supported RAM expansion cartridges that were officially made available in 3, 8 and 16 Kilobyte capacities. These RAM cartridges provided more RAM capacity for applications that could take advantage of it.

Vic-20 Basic Hearts

“The VIC and your color TV set give you the ability to put colors everywhere on the screen. When you first turn on the VIC, the border, the cursor, and any characters on the screen are already in color. But that’s only the beginning. The VIC can display 8 cursor colors, 8 border colors and 16 screen colors!” — Personal Computing on the Vic-20, a friendly computer guide

Game Cartridges

Plug-in game cartridges allowed the Vic-20 to act very much like a video game system such as the Atari VCS or the Intellivision. Commodore didn’t shy away from the fact that the Vic-20 could play games, but took opportunities to point out that it could do MORE than just play games.

William Shatner (aka James T Kirk) starred in TV Commercials promoting the Vic-20 as more than just a game system. If captain Kirk recommended this particular computer, it surely must be a solid choice. A powerful instant buyer confidence boost for Commodore’s marketing efforts.

Vic-20 Game Cartridges

Depsite their typically simple innards, Vic-20 cartridges were quite large compared to the cartridges of other systems. Perhaps they felt it represented an increase in perceived value for the consumer.

By supporting cartridges the Vic was able to play games quickly and conveniently and several game companies would produce games for the Vic — including Atari. There were many well known games ported to the Vic-20. Atlantis, Centipede, Defender, Dig Dug, Demon Attack, Donkey Kong, Frogger, Galaxian, Gorf, Joust, Pac man and many other games were released on cartridge for the Vic-20.

Joysticks and Paddles

Commodore Joystick

The Vic-20 had a single joystick port, labelled the Control Port. You could purchase an official joystick from Commodore or use any 9 pin Joystick that was compatible with Atari computers or game consoles.

Commodore produced two official joysticks intended for use with the Vic and matching it in color. The early joystick models were nearly identical (except for the white top) to Atari’s Joysticks. The later Joystick from Commodore had a unique shape including a triangular handle (see photo).

Two player games were possible on the Vic only by taking turns with the Joystick, using paddle controllers or by having one player use the keyboard. It would have been nice if Commodore included support for a second control port.

It is possible to connect a second Joystick to the Vic-20’s user port with a custom interface. The downside to this approach was that it would only work with games that were designed to take advantage of it — which were far and few between.

Vic-20 Joystick Port

The Vic-20 supported two Paddle controllers which plugged into the single control port. They were physically compatible with Atari paddles, but due to having a different Potentiometer would behave a little differently.

Cassette Tapes and Floppy Disks

Floppy disk drives were expensive at the time that the Vic-20 was released. Due to this many folks opted for the less expensive and more pedestrian Datassette for data storage and retrieval. These units used standard cassette tapes.

Unlike some computers which could use regular old tape recorders, Commodore (like Atari) wanted you to purchase a tape drive from them. To this end they built a proprietary interface for their tape drives. This basically meant you had to buy a tape drive for your Vic-20 from Commodore.

Vic-20 Datasette

During the early eighties music was commonly sold on cassette tapes. People were familiar with them and blank tapes were readily available.

Cassette tapes would prove to be slower, less convenient and less reliable when compared to floppy disks. Commodore released their VIC-1540 and later VIC-1541 floppy disk drives which used 5¼ inch floppy disks that could store approximately 170K of data.

As the disk operating system was built into the drive itself, even an unexpanded Vic with only 5K could use a disk drive. By comparison, Atari’s 8 bit computers require more RAM to use their Disk Operating Systems.

Friendly Documentation

Vic Character

The Vic-20 came with friendly documentation that allowed a new user to explore many of the machine’s capabilities. It even came with a few type in games such as the famous tank versus ufo game.

The Vic-20 Programmer’s reference manual is an excellent book that delves into more complicated topics including defining your own custom character sets and getting started with machine language.

“Your VIC has four voices … that is, it can “sing” four different notes to you at the same time! You might think of them as soprano, alto, tenor, and noise. Each of the voices has a particular “speaker control number”. By using this number, we can turn the speaker “on” and use it to create a musical note or sound effect.” — Personal Computing on the Vic-20, a friendly computer guide

Various Models

The original Vic-20 uses a 2 prong power supply. This model can also be identified by it’s monochromatic name badge on the top of the case.

The later cost-reduced Vic-20 uses a circular DIN connector for it’s power supply. It is identical to the power connector found on the Commodore 64. These units typically had cooler internal case temperatures and did not require a large internal heat sink like the first generation of Vics.

The cost reduced Vic could also be identified by their colorful name badges. Enthusiasts sometimes refer to these as Rainbow Vics.

The cost reduced version of the Vic-20 can use a power supply from a Commodore 64. The Vic-20’s power supply should NOT be used on a Commodore 64 (which requires more power).

Vic-20s were sold worldwide. The German Vic was known as the VC-20 and the Japanese Vic as the VIC-1001. In Japan the Vic was the first computer to sell for under 10,00 yen.

Vic 20 function Keys

Online Resources

Here are just a few Vic-20 oriented websites from around the web.

  • Vic-20 Denial : Vic-20 related forums, wiki, high scores, links and games by Jeffrey Daniels. On the homepage you will find an in-browser, working Vic-20 emulator. A thriving and friendly community can be found in the forums along with a wealth of information.
  • Digital Press’s Vic-20 Screenshot Gallery. Multiple pages of Vic-20 game screenshots that you can browse through.
  • The Mega Cart : The Mega cart is a ram expansion cartridge that is also able to store mulitple cartridge binaries and has many built-in programming tools including a hardware reset button.
  • Connect a Vic-20 to a PC using the PC’s parallel port by building an XE1541 extended cable. With the appropriate software, this enables a PC to emulate a Commodore disk drive. Pre-built cables are also available.


Many influential people started their adventures with computers on the diminutive Vic-20. Linus Torvalds, best known as the father of Linux, began on a Commodore Vic-20. Several software engineers would start computing on a 5K Vic, including well known game programmer Jeff Minter.

Enthusiasts today appreciate the complete and yet simple architecture of Commodore’s Vic-20. It’s a great platform if you’re interested in retro computing and learning early computing fundamentals including 6502 machine language. It’s also fun just to appreciate the variety of games that were released on the Vic.


  1. The Vic was a good introduction to computers for me when I was a kid. I remember entering BASIC programs from books and magazines and saving them to Tape. I wrote my first programs on a Vic.

  2. The Vic=20 was the king of cartridge games. Early arcade style games like Omega Race, Choplifter and Serpentine were not bettered by the C=64.

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