Editing Commodore VIC-20

{{Infobox computer
| name         = Commodore VIC-20
| image        = [[File:Commodore-VIC-20-FL.jpg|250px]]
| caption      = Commodore VIC-20 – The Friendly Computer
| manufacturer = Commodore Business Machines
| type         = Home Computer
| release date = 1980 (Japan), 1981 (Worldwide)
| discontinued = January 1985
| price        = US$299.95 (1981)
| cpu          = MOS Technology 6502 @ 1.1 MHz (PAL) / 1.02 MHz (NTSC)
| memory       = 5 KB RAM (3.5 KB usable), expandable up to 32 KB
| storage      = External cassette tape (Datasette), optional 5.25" floppy disk drive
| display      = 176×184 pixels, 22×23 text characters, 16 colors
| sound        = 3 square wave generators + 1 noise channel (mono)
| dimensions   = 40.3 cm × 20.4 cm × 7.2 cm
| weight       = 1.8 kg
| os           = Commodore BASIC 2.0 (in ROM)
| predecessor  = [[Commodore PET 4000 Series]]
| successor    = [[Commodore 64]]
| codename     = VIC-20, VC-20 (Germany), VIC-1001 (Japan)
| model        = VIC-1001, VIC-20, VC-20
| logo         = [[File:Commodore VIC 20 logo.svg|200px]]
}}The '''Commodore VIC-20''' was a groundbreaking home computer introduced by Commodore Business Machines in 1980. Known as the VIC-1001 in Japan and the VC-20 in Germany, it was the first computer to sell over one million units, making computing accessible to the masses.

== Architecture and Processor ==
At its core, the VIC-20 utilized the '''MOS Technology 6502''' 8-bit microprocessor, operating at 1.1 MHz for PAL systems and 1.02 MHz for NTSC systems. This CPU was also employed in other notable systems like the Apple II and Commodore 64.

== Memory and Storage ==
The VIC-20 came with 5 KB of RAM, with approximately 3.5 KB available for user programs. Memory could be expanded up to 32 KB via external cartridges.

For storage, the VIC-20 relied on external devices:
* '''Datasette''' – a cassette tape drive for loading and saving programs.
* '''VIC-1540/VIC-1541''' – optional 5.25" floppy disk drives connected via the serial port.

== Display and Graphics ==
The VIC-20 featured a 176×184 pixel resolution with a text display of 22 columns by 23 rows. It supported a palette of 16 colors. Graphics were character-based, and while it lacked a bitmap mode, users could define custom characters for simple graphics and animations.

== Sound Capabilities ==
Sound was generated through the MOS Technology VIC chip, offering:
* Three square wave generators.
* One white noise generator.
* Overall volume control.

These features allowed for basic music and sound effects in games and applications.

== Input/Output and Expansion ==
The VIC-20 was equipped with several I/O ports:
* '''Cartridge Port''' – for software and memory expansion cartridges.
* '''User Port''' – for modems and user-designed peripherals.
* '''Serial Port''' – for printers and disk drives.
* '''Joystick Port''' – compatible with Atari-style joysticks.
* '''Cassette Port''' – for the Datasette.
* '''RF and Composite Video Outputs''' – for connection to TVs and monitors.

== General Maintenance ==
Over time, VIC-20 computers may experience issues common to vintage electronics, such as:

* Aging capacitors leading to power supply instability or failure.
* Keyboard contact wear causing unresponsive or erratic key behavior.
* Overheating of the linear voltage regulator (LM323K), potentially leading to case deformation or component damage.
* Degradation of the RF modulator affecting video output quality.

Regular maintenance, including capacitor replacement, keyboard cleaning, and ensuring proper heat dissipation, can help preserve the functionality of these systems. For detailed procedures, refer to the [[Commodore VIC-20 General Maintenance|Commodore VIC-20 Maintenance Guide]].

== PCB Schematics & Service Guide ==
The VIC-20 features a modular motherboard design, facilitating repairs and upgrades. Detailed schematics and service manuals are available within the [[Commodore VIC-20 Technical Manual]]. Notable assembly versions include:

* '''Assy 324003''' – Early NTSC models.
* '''Assy 251027-01''' – VIC-20CR revision D (NTSC, new design).
* '''Assy 324001-03''' – VC-20 rev.B (PAL, old design).

=== Motherboard Images ===
{| class="wikitable" style="width:75%; text-align:center;"
|-
! Logic Board !! Schematic Diagrams
|-
| [[File:VIC20 Logic Board.jpg|thumb|center|350px|Commodore VIC-20 Logic Board]]
| [[File:VIC20 Schematic.png|thumb|center|350px|VIC-20 Logic Board Schematic]]
|}

== Technical Documentation ==
For detailed technical information, refer to the following resources:
* [[Commodore VIC-20 Technical Manual]]
* [[Commodore VIC-20 Programmer's Reference Guide]]
* [[Commodore VIC-20 User Manual]]

== Gallery ==
<gallery mode="packed" heights="200">
File:Commodore VIC-20 Front.jpg|Front view of the Commodore VIC-20
File:Commodore VIC-20 Rear.jpg|Rear panel showing I/O ports
File:VIC20_Logic_Board.jpg|Internal motherboard layout
File:Commodore VIC-20 Datasette.jpg|Datasette cassette tape drive
</gallery>

== 🧪 Related Pages ==
* [[Commodore VIC-20 General Maintenance|Commodore VIC-20 Maintenance Guide]]
* [[Commodore VIC-20 Troubleshooting Guide]]
* [[Commodore VIC-20 Keyboard Repair Guide]]
* [[Commodore VIC-20 Capacitor Replacement Guide]]

[[Category:Commodore Systems]]