Commodore 64

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Platform - C64.png
Commodore 64
Commodore 64.jpg
Released: 1982-0?-??
Discontinued: 1994-04-??
Developer: Commodore
Type: Hardware

The Commodore 64 is an 8-bit home computer released by Commodore and the best-selling single model of personal computer in history. Unlike modern computers which boot into an operating system, the Commodore 64 boots into Commodore BASIC, a primitive programming language which uses little memory, but also is way too slow to do much.

For market research, Commodore engineers bought a Mattel Intellivision console, a Texas Instruments TI-99/4A home computer, and everything by Atari. They had a lot of fun, but were given very little time, causing several subsequent revisions and never-fixed bugs, especially in audio. After release, they faced pay freezes, so almost all left to found Ensoniq.

Many users came from the Commodore VIC 20 or the Sinclair ZX81. Some early games were visibly ported from Apple II, Atari 8-bit, and later the C64's archenemy, the Sinclair ZX Spectrum. By 1989, Europeans were going for the Commodore Amiga, and Americans directly for DOS.


Software is either typed in BASIC or loaded from a tape cassette, two-sided 5'25" disk, or ROM cartridge. Although Commodore released 3'5" disk drives, no games are known to support them.

Even Commodore's built-in loaders are so slow that many hobbyists and companies developed and acquired fast loaders. Tape loaders are still slowed down by hardware, but some, most famously Novaload, Ocean Loaders (C64) and Invade-a-load (C64), make up by entertaining the gamer with pictures and music while loading. This is fondly remembered in the UK, where disk drives were especially expensive. Disk loaders can be much faster, if more so when blanking the screen and not doing anything else.



The MAX MACHINE was only released in Japan. It has no CIA2 chip and no built-in ROM, which means you cannot use disks and need a game cartridge or BASIC cartridge, like a console. Like the later Nintendo Entertainment System, it has only 2 KB RAM. Uniquely, it does have a 3.5 mm audio output.

Commodore had HAL Laboratory develop several games. The model was announced in the USA and UK as Ultimax and in Germany as VC 10, but cancelled as the backward-compatible C64 became cheaper.

Commodore 64

Commodore 64

Due to its case, the original C64 is nicknamed breadbox.


The Executive 64 is a portable C64 with a built-in disk drive and 5" color monitor, but no tape port or battery. You were supposed to carry it like a suitcase and put it on your host's table like a projector, not your lap.

It always got favorable reception since late 1983, but was also heavy and very expensive.


The SX-64 manual mentions that the DX-64 has two built-in disk drives. Whether it was built is unknown.

Commodore 128

Main article: Commodore 128

Commodore 64C

The flat C64C (prematurely C 64 II in 64'er 6/86) prompted the biggest revisions of the C64 chips, including the 8580 sound chip. They appeared in 1986 and prevail since the early 1990s.

Commodore 64 Games System

Nothing more than a C64C disguised as a clunky gray console, the C64GS was announced in mid-1990 and deemed a failure within a year, during which the 16-bit Sega Genesis spread worldwide.

Due to lack of a keyboard, some old C64 cartridges are unplayable. Nevertheless, people remembered that cartridges are fast, and Ocean Software released some games exclusively on cartridge.

Music and Sound

Every model has a SID synthesizer chip, a 6502-based CPU, two CIA chips which provide two timers each, and a VIC-II video chip which plays a big role in timing.

Each timer can be used to play music and samples at any desired rate. However, most songs are instead synchronized with the screen refresh to avoid irregular skips through the video chip. This is why most song tempos are (examples given for PAL and 4/4 time) 94, 125, 150 or 188 BPM rather than anything between.

On the wrong region's machine, pitch is off by 4% (65 cents) and speed by up to 19%. This speed difference can worsen bugs in SID's envelope, muting notes. The clocks are:

Region Chips Screen refresh
Old NTSC (until mid-1983) 1022727 Hz 60.993 Hz
NTSC (since mid-1983) 59.826 Hz
PAL 985248 Hz 50.125 Hz

Several hobbyists and companies created hardware that plug into the cartridge port, user port, or joystick port, either for themselves or the general public:

However, apart from sampler output and Mark Dickenson's stereo modification in the Sidplayer scene, extra hardware never caught on in Commodore games.


Many composers programmed their own drivers in 6502 assembly or machine language, BASIC (beginners), Ascompiler 64 (readers of 64'er 1/86), STAB-1 or Action! (two exotic developers), and typed numbers that equated to notes and instruments.

Those, who were not big sound programmers, used off-the-shelf music editors or hacked drivers by popular composers, especially Rob Hubbard's. Some did modify the drivers to make them smaller, faster, relocate them within RAM, allow sound effects (from other drivers), add modulations, or embed songs into their games at all.

In 1983, games started playing speech on SID's 4th voice. In 1987, Martin Galway, Oscar Giesen and Chris Hülsbeck popularized 4-voice music. How samples were made is individual. Those, who could not, used drums ripped from Peter Fröhlich's Funky Drummer and Hülsbeck's songs.

When porting to another region, pitches and durations are ideally converted, although, if anything, most NTSC ports simply skip one tick out of 6. Also, many people copied the note frequencies from wrong sources, ignorantly detuning songs on their own computer. The common tunings are:

450 Hz 434 Hz Commodore's faulty datasheet
440 Hz 424 Hz Correct NTSC values
457 Hz 440 Hz Correct PAL values