Sunday, February 12, 2006

Commodore 64

Commodore 64[EXTRACT]

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For the hip hop group, see Commodore 64 (band).
Commodore 64
Commodore 64 (circa 1982)
Type: Home computer
Developer: Commodore Business Machines (CBM)
Released: January, 1983
Processor(s): 1.023 MHz MOS Technology 6510 processor
Website: [2]

The Commodore 64 (C64, CBM 64/CBM64, C= 64) is a home computer with 64 kilobytes of RAM that was popular in the 1980s. Released by Commodore Business Machines (CBM) to the public in August 1982 at a price of US$ 595, it offered sound and graphics performance that was good compared to the standard at that time. During the Commodore 64's lifetime (between 1982 and 1993), total sales exceeded 22 million units. According to the Guinness Book of World Records, the Commodore 64 still remains the best selling computer model of all time.

Unlike computers that were distributed only through authorized dealers, Commodore also targeted department stores and toy stores. The unit could be plugged directly into a television set and play games, giving it much of the appeal of dedicated video game consoles like the Atari 2600. The pricing of the C64 is considered to be a major catalyst in the video game crash of 1983.

Approximately 10,000 software titles were made for the Commodore 64—this includes development tools, office applications, and games. The machine is also credited with popularizing the computer demo scene. Though the original hardware is now used only by a few hobbyists, emulators allow anyone with a modern computer to run these programs on their desktop.





Close-up of C64
Close-up of C64

In January 1981, MOS Technology, Inc., Commodore's integrated-circuit design subsidiary, initiated a project to design the graphic and audio chips for a next generation video game console. Design work for the chips was completed in November 1981, but the console project was soon cancelled after a meeting with Commodore president Jack Tramiel. Tramiel wanted the chips to form the base for a sequel to the very popular VIC-20. He proposed that the new system ship with with 64 kB of RAM, which was double the quantity that most home computers contained in late 1981. Although 64 kB of RAM cost over US$ 100 at the time, Tramiel knew that DRAM prices were falling, and would drop to an acceptable level before full production was reached.

The design team was given less than two months to develop a working prototype — codenamed the VIC-30 — so that it could be finished in time for the winter Consumer Electronics Show in January 1982. The C64 made an impressive debut, as recalled by Production Engineer David A. Ziembicki: "All we saw at our booth were Atari people with their mouths dropping open, saying, 'How can you do that for $595?'" The answer, as it turned out, was vertical integration; thanks to Commodore's ownership of MOS Technology's semiconductor fabrication facilities, each C64 had an estimated production cost of only $135.

Winning the market war

The C64 faced a wide range of competing home computers at its introduction in August 1982. With an impressive price point coupled with the 64's advanced hardware, it quickly out-classed many of its competitors. In the United States the greatest competitors to the C64 were the Atari 800 and Apple II. The Atari 800 was very similar in hardware terms, but it was very expensive to build, which soon forced Atari to move their production to the Far East. It also forced Atari to redesign their machine to be more cost effective, resulting in the 600XL/800XL line. The aging Apple II was no match for the C64's graphics and sound abilities, but was very expandable with its internal expansion slots, a feature lacking in the 64.

In the United Kingdom, the primary competitors to the C64 were the British-built Sinclair ZX Spectrum and the Amstrad CPC. Released a few months ahead of the C64, and selling for almost half the price, the Spectrum quickly became the market leader. The C64 would rival the Spectrum in popularity in the latter half of the 1980s, eventually outliving the Spectrum (which was discontinued in 1992).

One key to the C64's success was Commodore's aggressive marketing tactics. Commodore sold the C64 not only through its network of authorized dealers, but also placed it on the shelves of department stores, discount stores, and toy stores. Since it had the ability to output composite video, the C64 did not require a specialized monitor, but could be plugged into a television set. This allowed it (like its predecessor, the VIC-20) to compete directly against video game consoles such as the Atari 2600.

Aggressive pricing of the C64 is considered to be a major catalyst in the video game crash of 1983. In 1983, Commodore offered a $100 rebate in the United States on the purchase of a C64 upon receipt of any video game console or computer. To take advantage of the $100 rebate, some mail-order dealers and retailers offered a Timex Sinclair 1000 for as little as $10 with purchase of a C64 so the consumer could send the computer to Commodore, collect the rebate, and pocket the difference.[3] Timex Corporation departed the marketplace within a year. The success of the VIC-20 and C64 also contributed significantly to the exit of Texas Instruments' TI-99/4A and other competitors from the field.

C64 successors and the 64C

Commodore SX-64 (1984)
Commodore SX-64 (1984)

In 1984 Commodore released the SX-64, a portable version of the C64. The SX-64 has the distinction of being the first full-color portable computer. The base unit featured a 5 inch (127 mm) CRT and an integral 1541 floppy disk drive. Although critically acclaimed, due to its significantly higher price over the standard C64, fewer than 10,000 had been sold by the time it was discontinued in 1986.

In 1984, Commodore released the Commodore Plus/4. While many industry critics viewed this as an attempt to replace the C64, it was in fact a replacement for the VIC-20. The Plus/4 offered a higher-color display, a better implementation of BASIC (V3.5), and built-in software. But because it was a replacement for the VIC-20 and not the C64, Commodore committed what was perceived by critics and consumers as a major strategic error by making it incompatible with a majority of the existing C64 software library. To top it all off, the Plus/4 lacked hardware sprite capability and had much poorer sound - even inferior to that of the VIC-20 - thus seriously underperforming in two of the areas that had made the C64 a star. Furthermore, none of the C64's external peripherals save for the monitor and most joysticks were compatible with the port connections on the Plus/4, and the promised floppy drives were not available for the first three months the Plus/4 was in the stores. The misconceived and misperceived new machine flopped, to no one's surprise except Commodore's, while demand for the C64 merely increased as old store stock was being liquidated to make room for the supposedly superior replacements.

On a side note, the Plus/4 was later dumped on TV audiences the next year via phone sales and two-minute "infomercials". Commodore created a dummy company called the C.O.M.B. Company. While the acronym reportedly stood for "Commodore Overstock Management Bureau", it was more commonly referred to as an acronym for "Crawling Out My Butt", referring to the sheer numbers of Plus/4s that were stuck in warehouses across the country that were eventually returned to Commodore.

Commodore was determined not to repeat the same mistake, and made sure that the eventual successors to the C64—the Commodore 128 and 128D computers (1985)—were as good as, and fully compatible with, the original, as well as offering a host of long-sought improvements (such as a structured BASIC with graphics and sound commands, 80-column display capability, and full CP/M compatibility). The basic design of the 128, in fact, had already been marketed successfully in the Northern European and Scandinavian countries as early as 1983 as the Commodore B-128. As the Commodore 128 and other manufacturers' more advanced computers came onto the market, Commodore positioned the 64 as an entry-level computer, lowering the price as necessary.

Commodore 64C system with 1541-II floppy drive and 1084S RGB monitor (1986)
Commodore 64C system with 1541-II floppy drive and 1084S RGB monitor (1986)

In 1986, Commodore released the Commodore 64C (C64C) computer, which was functionally identical to the original, but whose exterior design was remodelled in the spirit of the C128 and other contemporary design trends. In the U.S., the C64C often came bundled with the third-party GEOS GUI-based operating system.

An active demoscene

At the time of its introduction, the C64's graphics and sound capabilities were rivaled only by the Atari 8-bit family. This was at a time when most IBM PCs and compatibles had text-only graphics cards, green screen monitors, and sound consisting of squeaks and beeps from the built-in tiny, low-quality speaker.

Due to its advanced graphics and sound, the 64 is often credited with starting the computer subculture known as the demoscene (see Commodore 64 demos). As of the turn of the millennium, it is still being actively used as a demo machine, especially for music (its sound chip even being used in special sound cards for PCs). For all other than die-hard enthusiasts, however, the C64 lost its top position among demo coders when the 16-bit Atari ST and Commodore Amiga were released in the mid-80s.

The demoscene is far from being dead even more than 20 years after the C64 was invented. New games are still being developed. A noteworthy one is Enhanced Newcomer, which took almost 10 years of development.

The differences between PAL and NTSC C64s cause compatibility problems between US/Canadian C64s and those from most other countries. Most demos run only on PAL machines.

1990s and 2000s hardware

In 1990 the C64 was re-released in the form of a games console, called the C64 Games System (C64GS). It was basically a C64 motherboard modified to orient the cartridge connector to a vertical position, to allow cartridges to be inserted from above. A modified ROM replaced the BASIC interpreter with a boot screen to inform the user to insert a cartridge. Needless to say, the C64GS was another commercial failure for Commodore, and was never even released outside of Europe. In 1990/91, an advanced intended successor to the C64, the Commodore 65 (also known as the "C64DX"), was prototyped, but never released.

In the summer of 2004, after an absence from the marketplace of more than 10 years, PC manufacturer Tulip Computers BV (owners of the Commodore brand since 1997) announced the C64 Direct-to-TV (C64DTV), a joystick-based TV game based on the C64 with 30 games built into ROM. Designed by Jeri Ellsworth, a self-taught computer designer who had earlier designed the modern C-One C64 implementation, the C64DTV was similar in concept to other mini-consoles based on the Atari 2600 and Intellivision which had gained modest success earlier in the decade. The product was advertised on QVC in the United States for the 2004 holiday season. Some users have installed 1541 floppy disk drives, hard drives, second joysticks and keyboards to these units, which give the DTV devices nearly all of the capabilities of a full Commodore 64. The DTV hardware is also used in the mini-console/game Hummer, sold at Radio Shack mid-2005.

As of 2005 C64 enthusiasts still develop new hardware, including Ethernet cards, specially adapted hard disks and Flash Card interfaces.


Graphics and sound

The C64 used an 8-bit MOS Technology 6510 microprocessor (a close derivative of the 6502 with an added 6-bit internal I/O port that in the C64 is used for two purposes: to bank-switch the machine's ROM in and out of the processor's address space, and to operate the datasette tape recorder) and had 64 kilobytes of RAM, of which 38 kB were available to built-in Commodore BASIC 2.0.

The graphics chip, VIC-II, featured 16 colors, eight sprites, scrolling capabilities, and two bitmap graphics modes. The standard text mode featured 40 columns, like most Commodore PET models. Computer/video game and demo programmers quickly learned how to exploit quirks in the VIC-II to gain additional capabilities, like making more than 8 sprites appear, and move, simultaneously.

The sound chip, SID, had three channels with several different waveforms, ring modulation and filter capabilities. It, too, was very advanced for its time. It was designed by Bob Yannes, who would later co-found synthesizer company Ensoniq. Yannes criticized other contemporary computer sound chips as "primitive, obviously (...) designed by people who knew nothing about music." Often the game music became a hit of its own among C64 users. Well-known composers and programmers of game music on the C64 were Rob Hubbard, Ben Daglish and Martin Galway, among many others.

The SID chip has a distinctive sound which retained a following of devotees. In 1999, Swedish company Elektron produced a "SID Station" synth module, built around the SID chip, using remaining stocks of the chip.

Hardware revisions

Cost reduction was the driving force for hardware revisions to the C64's motherboard. Reducing manufacturing costs was vitally important to Commodore's survival during the price war and leaner years of the 16-bit era. The C64's original (NMOS based) motherboard would go through two major redesigns, (and numerous sub-revisions) exchanging positions of the VIC-II, SID and PLA chips. Initially, a large proportion of the cost was lowered by reducing the number of discrete components used, such as diodes and resistors.

An early C64 motherboard. (Rev A PAL 1982)
An early C64 motherboard. (Rev A PAL 1982)
A C64C motherboard ("C64E" Rev B PAL 1992)
A C64C motherboard ("C64E" Rev B PAL 1992)

The VIC-II was manufactured with 5 micrometer NMOS technology, clocked at 8 MHz. At such a high clock rate, it generated a lot of heat, forcing MOS Technology to use a ceramic DIL package (called a "CERDIP"). The ceramic package was more expensive, but it dissipated heat more effectively than plastic.

After a redesign in 1983, the VIC-II was encased in a plastic DIL package, which reduced costs substantially, but it did not eliminate the heat problem. Without a ceramic package, the VIC-II required the use of a heatsink. To avoid extra cost, the metal RF shielding doubled as the heatsink for the VIC, although not all units shipped with this type of shielding. Most C64s in Europe shipped with a cardboard RF shield, coated with a layer of metal foil. The effectiveness of the cardboard was highly questionable, and worse still it acted as an insulator, blocking airflow which trapped heat generated by the SID, VIC and PLA chips.

The SID was manufactured using NMOS at 7 and in some areas 6 micrometers. The prototype SID and some very early production models featured a ceramic DIL package, but unlike the VIC-II, these are extremely rare as the SID was encased in plastic when production started in early 1982.

In 1986 Commodore released the last revision to the "classic" C64 motherboard. It was otherwise identical to the 1984 design, except that it now used two 64 kbit ×4 DRAM chips rather than the original eight 64 kbit ×1.

After the release of the C64C, MOS Technology began to reconfigure the C64's chipset to use HMOS technology. The main benefit of using HMOS was that it required less voltage to drive the IC, which consequently generates less heat. This enhanced the overall reliability of the SID and VIC-II. The new chipset was re-numbered to 85xx in order to reflect the change to HMOS.

In 1987 Commodore released C64Cs with a totally redesigned motherboard commonly known as a "short board". The new board used the new HMOS chipset, featuring new 64-pin PLA chip. The new "SuperPLA" as it was dubbed, integrated many discrete components and TTL chips. The 2114 color RAM was integrated into the last revision of the PLA.

Power problems

The C64 used an external power supply. While this saved valuable space within the computer's case, the supply itself was inadequate for the C64's power requirements and often failed from overheating. Commodore's infamous "brick" power supplies being the most likely offenders. Many users purchased heavier-duty, better-cooled, third-party power supplies. Later in the Commodore's lifetime, third-party power supplies became increasingly important when used in conjuction with Creative Micro Designs' peripherals. Of particular note, a C64 coupled with a RAM expansion or CMD SuperCPU required more power than the original Commodore power supply could provide.

External hardware

Main article: Commodore 64 peripherals


Main article: Commodore 64 software

Representative screenshots

Additional screenshots can be found on the Commodore 64 software page.


Internal hardware

  • Microprocessor CPU:
  • Video: MOS Technology VIC-II 6567/8567 (NTSC), 6569/8569 (PAL)
    • 16 colors
    • Text mode: 40×25 characters; 256 user-defined chars (8×8 pixels, or 4×8 in multicolor mode); 4-bit color RAM defines foreground color
    • Bitmap modes: 320×200 (2 colors in each 8×8 block), 160×200 (3 colors plus background in each 4×8 block)
    • 8 hardware sprites of 24×21 pixels (12×21 in multicolor mode)
    • Smooth scrolling, raster interrupts
  • Sound: MOS Technology 6581/8580 SID
  • RAM:
    • 64 kB (65,536 bytes), of which 38 kB minus 1 byte (38911 bytes) were available for BASIC programs
    • 0.5 kB color RAM (1 k nybbles)
    • Expandable to 320 kB with Commodore 1764 256 kB RAM Expansion Unit (REU); although only 64 kB directly accessible; REU mostly intended for GEOS. REUs of 128 kB and 512 kB, originally designed for the C128, were also available, but required the user to buy a stronger power supply from some third party supplier; with the 1764 this was included.
  • ROM:
    • 20 kB (9 kB BASIC 2.0; 7 kB KERNAL; 4 k character generator, providing two 2 k character sets)

I/O ports and power supply

  • I/O ports:
    • 8-pin DIN plug containing composite video output, separate Y/C outputs, and sound input/output. (Some early C64 units utilized a 5-pin DIN connector that omitted the Y/C output.)
    • Integrated RF modulator antenna output via a RCA connector
    • 2 × screwless DE9M game controller ports (compatible with Atari 2600 controllers), each supporting five digital inputs and two analog inputs. Available peripherals included digital joysticks, analog paddles, a light pen, the Commodore 1351 mouse, and the unique KoalaPad.
    • Cartridge expansion slot (slot for edge connector with 6510 CPU address/data bus lines and control signals, as well as GND and voltage pins; used for program modules and memory expansions, among others)
    • PET-type Datassette 300 baud tape interface (edge connector with cassette motor/read/write/sense signals and GND and +5 V pins; the motor pin is powered to directly supply the motor)
    • User port (edge connector with TTL-level RS-232 signals, for modems, etc; and byte-parallel signals which can be used to drive third-party parallel printers, among other things; with 17 logic signals, 7 GND and voltage pins, including 9 V AC voltage)
    • Serial bus (serial version of IEEE-488, 6-pin DIN plug) for CBM printers and disk drives
  • Power supply: 5 V DC and 9 V AC from external "monolithic power brick", attached to computer's 7-pin female DIN-connector


  • The Commodore 64's startup screen was spoofed in the startup sequence of the 2002 computer/video game Grand Theft Auto: Vice City.
  • Population: Tire, a game from animated flash site, also starts up with a spoofed screen of the Commodore 64, called "Compydore 64".
  • The Commodore 64's BASIC V2, the programming language which came built-in the computer, could be crashed by executing PRINT""+-[x] (where x is any integer).


  1. ^  A contemporary rumor stated that while Commodore scavenged most trade-in computers for spare parts, its employees used the TS1000s as door stops.

See also



  • Bagnall, Brian (2005). On the Edge: the Spectacular Rise and Fall of Commodore. Variant Press. ISBN 0-9738649-0-7.
  • Commodore Business Machines, Inc., Computer Systems Division (1982). Commodore 64 Programmer's Reference Guide. Self-published by CBM. ISBN 0-672-22056-3.
  • Angerhausen, M.; Becker, Dr. A.; English, L.; Gerits, K. (1983, 84). The Anatomy of the Commodore 64. Abacus Software (US ed.) / First Publishing Ltd. (UK ed.). ISBN 0-948015-004 (UK ed.). German original edition published by Data Becker GmbH, Düsseldorf.
  • Tomczyk, Michael (1984). The Home Computer Wars: An Insider's Account of Commodore and Jack Tramiel. COMPUTE! Publications, Inc. ISBN 0-942386-75-2.

Magazine articles

  • Perry, Tekla S.; Wallich, Paul. "Design case history: the Commodore 64". IEEE Spectrum. March 1985. [4]
  • Jeffries, Ron. "A best buy for '83: Commodore 64". Creative Computing, January 1983. [5]

External links

Wikimedia Commons has media related to:


Link portals


  • The Digital Dungeon (TDD) – FTP site full of old and recent C64 software
  • – An archive of C64 demos
  • GameBase 64 – C64 game software information site
  • Lemon 64 – Site with general information, game reviews and a forum
  • Games That Weren't 64 – Large project archive dedicated to finding and researching lost C64 games.
  • C64HQ – Graphically nice site with interviews of famous C64 game creators & sceners, game- and demodownloads and more
  • C64 Walkthrough Site – Walkthrough and solution archive for C64 adventure games with discussion forum
  • Project 64 – Manuals for C64/128 games and software
  • The Ultimate C64 Tape Page – Large preservation archive of C64 cassettes. Also contains scans of cassette covers and manuals
  • The C64 Internet Games Database – over 30000 entries! After a 64 game? Then find it here!
  • The-Commodore-Zone – Archive of C64 games, speech box, legends of the 64, discussion forum, online databases, links


  • SIDPLAY – A freeware SID music player (a "SID chip emulator")
  • HVSC - High Voltage SID Collection – Large collection of SID files which can be downloaded as a complete archive for use with SIDPLAY
  • C64 Music – Commodore 64 music in the real world & other related SID stories blog
  • Press Play on Tape – Danish 'C64 revival' band
  • Mr. Pacman – American band that performs C64 covers & re-workings; band member Silver Ghost uses a SX-64 as a bass synthesizer
  • SLAY Radio – Radio with live DJs playing Remixes of C64 game and demo music
  • – Remixes of C64 game music in mp3-format
  • Remix64 – Online magazine and community centre for the C64 music remixing scene
  • Sidstation by Elektron – Swedish company Elektron makes the Sidstation, a synthesizer using the C64 SID chip, with midi support and realtime tweaking
  • Tree Wave – American band that creates original and sophisticated music and video using Commodore 64 machines and other 8-bit computers and peripherals, often for live performances.
  • Welle:Erdball – German bitpop group who credit their beefed-up C64 as a band member
  • Kawasaki Synthesizer & Rhythm Rocker – One of the first standalone(no additional hardware required other than C64/PC itself) music software ever written for personal computer history which became widely accepted and commercially successful. The page is provided by the author Ryo Kawasaki himself.



                List of Commodore microcomputers

MOS Technology 6502-based (8-bit):   MOS/CBM KIM-1 | PET/CBM | CBM-II (aka B/P series) | VIC-20/VC-20 | C64 | SX-64 | C16 & 116 | Plus/4 | C128

M68K-based (16/32-bit):   Amiga 1000 | Amiga 500 | Amiga 2000 | Amiga 500+ | Amiga 2500 | Amiga 3000, UX, T | Amiga 600 | Amiga 1200 | Amiga 4000