Vintage & Retro Computer Project
Rescue, Repair & Relive Yesterdays Technology

Todays Date: April 23, 2024

RETRO DATE: Late 80’s Early 90’s

Commodore VIC-20

The Commodore VIC-20 was a home computer released in 1981 by Commodore International. It was the first computer to sell over one million units and was popular for its affordability and ease of use.

The VIC-20 featured a 5KB memory, which was expandable up to 32KB, and a MOS 6502 microprocessor. It was designed to be used with a television as a display and had a built-in cartridge port for games and other programs.


My first experience with the Commodore VIC-20 came after owning both my Commodore 16 and Commodore 64. This had an impact on my experience as I never really got the enjoyment out of this system due to the newer systems I had previously owned.

The other Commodore systems I owned had more memory and more processing power, so this was to be an entry level system. I have included a VIC-20 in my collection as I did use one in the past, and wanted to make sure my collection was complete with the breadbin models.

I purchased two VIC-20’s due to the first one being very yellow and had brown function keys like the Commodore 64. I wanted a VIC-20 that represented the version I used which was a lot lighter case and had orange funtion keys.

Now I have two, I have one as a spare to provide components should my main one suffer any issues.

First VIC-20


After cleaning, the condition of the VIC is very good apart from a few marks and age related yellowing of the case and keyboard. I’ve tested the cartridge, cassette and joystick ports and all are working. All the keys on the keyboard work. The VIC has been on for several hours running games with no issues.

The memory cartridge allows any combination of RAM settings and includes memory in the cartridge area for playing cartridge based games.

VIC 20

Power Supply

35K Selectable
RAM Cartridge

TV Lead

After my Ebay purchase arrived, I took the computer apart to check the components and clean the case as much as possible as it was very yellow.

Despite the case and keyboard being much cleaner, it still was very yellow, and I also noticed that on this model, the function keys were the same colour as that on the Commodore 64, and I wanted the authenic orange function keys.

I returned to Ebay to search for a cleaner model which more represented the ligher colour of the VIC 20 and one with orange keys.

Second VIC-20


***Budget Range***

  • Commodore Vic-20 Late revision
  • This model uses the same power supply as the C64
  • Keyboard functions ok
  • Capacitors are inspected for leakage and tested for component value
  • Diagnostic software run to check all inputs and outputs and soak tested for reliability.
  • 1 Month Warranty is included in the sale
  • Only Includes Commodore Machine

The second VIC 20 was more like the original colour both the case and the keyboard. It did require a little cleaning and now has looks original from the period.


Diagnostic Package

Keyboard Connector
Cassette Connector

Joystick Connector
Serial Port Connector
User Port Connector

The diagnostic cartridge & harness tests the keyboard, serial port, cassette port, joystick port & user port.

Address lines, timers and the sound is also tested.

Replacement PSU

The original VIC 20 PSU was tested for voltages and at time of testing, all the correct voltages were displayed. The downside is that the PSU is over 30 years old and they are known to cause issues without warning and sending over voltages in to the VIC 20.

The first you know about it is when your VIC 20 starts behaving odly and this may be a damaged chip. Due to the shortage of spares and the cost of the ones that are available, the cost of a replacement PSU is cheaper than fixing any potential damage that may be caused by an old original PSU.

Penultimate Cartridge

As neither of my VIC 20 included either a tape drive or any software, the best solution was to purchase the VIC20 Penultimate Cartridge.

The cartrige comes loaded with a large selection of games, memory expansions and utilites.

As marketed, its the only cartridge you will ever need for
your VIC 20.


I combined the best parts from both VIC-20’s to make the most future proofed, authentic and clean version.

The case from second VIC-20 was cleaner and lighter, the keyboard from second VIC-20 had authentic orange function keys, and the motherboard from first VIC-20 had a better video display.

I upgraded the PSU for a modern equivelent to protect VIC-20 from over voltages and added heatsink to protect critical chips.

Case from second VIC-20

Keyboard from second VIC-20

Motherboard from first VIC-20

Replaced Power Supply

Heatsink added to critical chips