The Commodore 64, also called the C64, is an 8-bit home computer that was first introduced in January 1982 by Commodore International. It was first displayed at the Consumer Electronics Show in Las Vegas from January 7–10, 1982. It holds the record in the Guinness World Records as the best-selling desktop computer model of all time, with estimates suggesting between 12.5 and 17 million units were sold. Production began in early 1982, and it was marketed in August 1982 for $595 (about $1,990 in 2025). The C64 came after the VIC-20 and Commodore PET computers and was named for its 64 kibibytes (65,536 bytes) of RAM. It had special features like multicolor images and a custom chip to create sounds and visuals, which made its graphics and audio better than other systems without such technology.

The C64 was the most popular computer in the low-end market for most of the 1980s, except in the UK, France, and Japan, where it had limited success. From 1983 to 1986, the C64 had between 30% and 40% of the US market and sold about 2 million units each year, outperforming IBM PC compatibles, the Apple II, and Atari 8-bit computers. Sam Tramiel, who later became president of Atari and was the son of Commodore’s founder, said in a 1989 interview that Commodore produced 400,000 C64s each month for several years. In the UK, the C64 competed with the BBC Micro, ZX Spectrum, and later the Amstrad CPC 464, but it remained the second most popular computer after the ZX Spectrum. In Japan and France, the C64 was not successful because those markets were dominated by other computers, such as the NEC PC-8801, Sharp X1, Fujitsu FM-7, MSX, ZX Spectrum, Thomson MO5, TO7, and Amstrad CPC 464.

Part of the C64’s success was its sale in regular retail stores, not just electronics or hobbyist specialty stores. Commodore made many of its parts in-house to control costs, including custom chips from MOS Technology. In the United States, the C64 is often compared to the Ford Model T for its role in making a new technology widely available to middle-class households through affordable mass production. About 10,000 software programs were created for the C64, including tools for work, productivity, and video games. Today, C64 emulators let people use modern computers or video game consoles to run these programs. The C64 helped start the computer demoscene and is still used by some hobbyists. In 2011, 17 years after it was no longer sold, studies found that 87% of people still recognized the C64 model.

History

In January 1981, MOS Technology, a part of Commodore that designs computer chips, started a project to create the graphics and sound chips for a new video game console. The chips, called MOS Technology VIC-II (Video Integrated Circuit for graphics) and MOS Technology SID (Sound Interface Device for audio), were completed in November 1981. Commodore then began a project to build a new game console called the Ultimax or MAX Machine, designed by Yash Terakura from Commodore Japan. This project was later canceled after only a few units were made for the Japanese market.

At the same time, Robert "Bob" Russell (a system programmer and architect for the VIC-20) and Robert "Bob" Yannes (engineer of the SID) were unhappy with Commodore’s current products, which were based on the Commodore PET line for business users. With help from Al Charpentier (engineer of the VIC-II) and Charles Winterble (manager of MOS Technology), they suggested to Commodore’s CEO, Jack Tramiel, that the company should create a low-cost follow-up to the VIC-20. Tramiel wanted the new computer to have 64 KB of random-access memory (RAM). Though 64K DRAM chips cost over $100 at the time, Tramiel believed prices would drop before full production began.

Because Commodore had its own chip-making factory, which was not fully used, the team could design the computer quickly and at lower cost. The chips were finished by November, and Charpentier, Winterble, and Tramiel decided to move forward with the project. They set a deadline for the first weekend of January 1982 to prepare for the Consumer Electronics Show (CES).

The product was first called the VIC-40, meant to replace the popular VIC-20. The team included Yash Terakura, Shiraz Shivji, Bob Russell, Bob Yannes, and David A. Ziembicki. They completed the design, prototypes, and sample software in time for the show, working hard during Thanksgiving and Christmas. The machine used the same case, motherboard size, and Commodore BASIC 2.0 in ROM as the VIC-20. BASIC also acted as the user interface, appearing at the READY prompt when the computer started.

Before the show, the VIC-40 was renamed C64. The C64 made a strong impression at the January 1982 CES, as described by Production Engineer David A. Ziembicki: "At our booth, people from Atari were surprised, saying, 'How can you do that for $595?'" The answer was vertical integration—Commodore’s ownership of its chip-making factories allowed each C64 to cost about $135 to produce.

In July 1983, BYTE magazine noted the C64 sold for $595 and was a top contender in the under-$1,000 personal computer market. It praised the SID chip as a high-quality music synthesizer but criticized Commodore BASIC 2.0, the slow floppy disk drive, and quality control. BYTE also mentioned that BASIC 2.0 had limited features, such as the need to use POKE commands for graphics or sound. This was one of the few times a magazine warned about BASIC 2.0.

Creative Computing called the C64 "the overwhelming winner" in the under-$500 home computer category in December 1984, despite noting its slow disk drive and limited ports. The Tandy Color Computer was the runner-up, and the Apple II won in the over-$500 category.

Commodore had a history of announcing products that never reached the market, so it worked quickly to launch the C64. Production began in spring 1982, and large shipments started in August. The C64 faced competition from many home computers, but its lower price and flexible hardware helped it outsell many rivals.

In the United States, the C64’s main competitors were the Atari 8-bit computers, the Apple II, and the TI-99/4A. The Atari 400 and 800 were expensive to make due to FCC regulations. The C64 and Apple II had different designs: the Apple II used expansion slots for peripherals, while the C64 used built-in ports. Commodore shared detailed specifications for its models, unlike the TI-99/4A, which focused on less technical users.

Early C64 sales were slow due to a lack of software, reliability issues with the PLA chip, and shortages of 1541 disk drives. However, software availability grew in 1983, and sales increased rapidly.

Commodore sold the C64 through dealers, department stores, discount stores, toy stores, and college bookstores. The C64 had a built-in RF modulator, allowing it to connect to any television, competing with video game consoles like the Atari 2600. It could also output a composite video signal, avoiding the RF modulator, and used a separate luminance/chroma signal for better video quality.

Commodore’s aggressive pricing, including a $100 rebate for trading in other consoles or computers, contributed to the video game crash of 1983. Some retailers sold the Timex Sinclair 1000 for as little as $10 with a C64 purchase, leading to Timex leaving the computer market within a year.

C64 family

In 1982, Commodore released the MAX Machine in Japan. It was called the Ultimax in the United States and the VC-10 in Germany. The MAX was designed as a game console with basic computing power and used a simplified version of the hardware later used in the C64. The MAX was stopped from being sold months after its release due to low sales in Japan.

In 1983, Commodore tried to compete with the Apple II in the US education market by releasing the Educator 64. This device was essentially a C64 and a green monochrome monitor in a PET case. Schools preferred the PET’s single, strong metal design over the C64’s separate parts, which were easier to break, damage, or steal. Schools did not choose the Educator 64 because the Apple IIe offered more software and hardware options, and the Educator 64 was made in limited numbers.

Also in 1983, Commodore released the SX-64, a portable version of the C64. The SX-64 was the first commercial full-color portable computer. Earlier portable computers only had monochrome ("green screen") displays, but the SX-64 had a 5-inch color cathode ray tube (CRT) and one built-in 1541 floppy disk drive. Commodore advertised that the SX-64 would have two 1541 drives, but only one was included. The other drive became a storage slot instead. Unlike most C64 models, the SX-64 did not have a datasette connector, so using external cassette tapes was not possible.

Two designers at Commodore, Fred Bowen and Bil Herd, worked to fix the problems of the Plus/4. They planned for the C64’s successors, the Commodore 128 and 128D (1985), to improve on the C64 and avoid the Plus/4’s flaws. These successors had features like a BASIC programming language with graphics and sound commands, an 80-column display, and full CP/M compatibility. Bowen and Herd secretly decided to make the Commodore 128 compatible with the C64 without management approval. They kept the plan secret until the project was too far along to change before the Consumer Electronics Show (CES) in Las Vegas. After learning about the compatibility, Commodore’s marketing department announced the C128 would be 100% compatible with the C64. To ensure full compatibility, the 128 design was changed to include a separate "64 mode" with a complete C64 environment.

The C64’s designers planned to release a new, wedge-shaped case within a year of the C64’s launch, but this did not happen. In 1986, Commodore released the 64C, which was functionally the same as the original C64. The original C64 was nicknamed the "Breadbin 64" after the 64C’s release. The 64C had a redesigned, sleeker exterior similar to the Commodore 128. It used updated versions of the SID, VIC-II, and I/O chips. Some models had graphic symbols printed on the top of the keys instead of the front. The sound chip (SID) was changed to the MOS 8580, reducing its voltage from 12V to 9V. This change affected how some music and sound effects sounded. The 64 KiB RAM was reduced from eight chips to two. BASIC and the KERNAL were combined into one 16 KiB ROM chip. The PLA chip and some TTL chips were integrated into a single DIL 64-pin chip. The "252535-01" PLA chip also included color RAM. The smaller design made it impossible to add certain internal expansions, like a floppy-speeder. In the United States, the 64C often came with a third-party GEOS graphical user interface (GUI) operating system and software for Quantum Link. The 1541 floppy drive was also redesigned as the 1541C. Later, a smaller 1541-II model and the 800 KB 3.5-inch microfloppy 1581 were introduced.

In 1990, the C64 was repackaged as a game console called the C64 Games System (C64GS). Most external connections were removed, and a simple modification to the 64C’s motherboard allowed cartridges to be inserted from above. A modified ROM replaced the BASIC interpreter with a boot screen that told users to insert a cartridge. The C64GS was designed to compete with the Nintendo Entertainment System and Sega’s Master System but had very low sales. It was a commercial failure and was never sold outside Europe. The C64GS lacked a keyboard, so software requiring a keyboard could not be used.

In 1990, an advanced successor to the C64, the Commodore 65 (also called the "C64DX"), was planned but canceled in 1991 by Commodore’s chairman, Irving Gould. The C65 had powerful features for an 8-bit computer, comparable to the 16-bit Apple IIGS. For example, it could display 256 colors on screen, while OCS-based Amigas could only show 64 in HalfBrite mode (32 colors with half-brightness). No specific reason was given for the C65’s cancellation, but it would have competed with Commodore’s lower-end Amigas and the Commodore CDTV.

Software

In 1982, the C64's graphics and sound abilities were only matched by the Atari 8-bit computers and were much better than the Apple II. The C64 is often credited with starting the demoscene subculture (see Commodore 64 demos). It is still used today in the demoscene, especially for music. Its SID sound chip is even used in special sound cards for PCs and in the Elektron SidStation synthesizer. Even though other computers soon matched its abilities, the C64 stayed a strong competitor to later video game consoles like the Nintendo Entertainment System (NES) and Master System, partly because of its large collection of software.

In the UK, most C64 software used cassette tapes because of lower incomes and the popularity of the ZX Spectrum. Few cassette-based C64 programs were released in the US after 1983. In North America, floppy disks were the main way to share software. The C64's cartridge slot was mostly used in its first two years in the US market and became less useful once floppy drives became more reliable and cheaper. Some games in the PAL region used bank switched cartridges to work around the 16 KiB memory limit.

Like many home computers from the early 1980s, the C64 came with a BASIC interpreter stored in its ROM. KERNAL, I/O, and tape/disk drive operations were controlled through special BASIC commands. The floppy drive had its own microprocessor and ROM for handling I/O tasks, similar to earlier systems like the CBM/PET and Atari 400 and 800. This meant no memory was used for a disk operating system, unlike systems such as the Apple II and TRS-80.

The C64 used Commodore BASIC 2.0 instead of the more advanced BASIC 4.0 from the PET series because it was not expected to need features for working with disks. The company believed few users would buy a disk drive, and using BASIC 2.0 made it easier for users of the VIC-20 to switch to the C64. "We chose BASIC 2.0 because users likely wouldn’t need direct disk commands. We saved memory space for features like color and sound instead of disk-related tools. This means you’ll need to use older methods for handling disks."

The version of Microsoft BASIC on the C64 lacked commands for sound or graphics and required users to use "PEEK and POKE" commands to control the graphics and sound chips directly. To add more features, Commodore created two cartridge-based extensions for BASIC 2.0: Simons' BASIC and Super Expander 64. Other programming languages available for the C64 included Pascal, C, Logo, Forth, and FORTRAN. Compilers for BASIC 2.0, such as Petspeed 2, Blitz, and Turbo Lightning, were also developed. Most commercial C64 software was written in assembly language, either on a larger computer or directly on the C64 using a machine code monitor or assembler. This helped speed and save memory. Some games, especially adventures, used high-level scripting languages and mixed BASIC with machine code.

Many third-party operating systems were created for the C64. In addition to the original GEOS, two GEOS-compatible systems, Wheels and GEOS megapatch, were developed. These required hardware upgrades. Other systems included WiNGS OS, LUnix (a Unix-like system), Contiki (an embedded system with a GUI), ACE, Asterix, DOS/65, and GeckOS. C64 OS, though not a full operating system, is still available and being developed. It includes a full GUI and modern features. A version of CP/M was released but required an external Z80 processor, which slowed performance. CP/M on the C64 and C128 had limited software because few companies made versions for Commodore disks. The C64 CP/M cartridge only worked with early 326298 motherboards.

In the 1980s, the C64 was used to run bulletin board systems with software like Punter BBS, Bizarre 64, Blue Board, C-Net, Color 64, CMBBS, C-Base, DMBBS, Image BBS, EBBS, and The Deadlock Deluxe BBS Construction Kit. These systems sometimes shared cracked software. As late as December 2013, 25 such systems were still active, accessible via Telnet. Major online services included Compunet (UK), CompuServe (US), The Source (US), and Minitel (France). These services often came with modems and free online time billed by the minute. Quantum Link (Q-Link), a US and Canadian online service for C64 and C128 computers, operated from 1985 to 1994. It was later renamed America Online and served IBM PCs and Macs. Q-Link was based on the PlayNET system.

The first graphical character-based interactive environment was Club Caribe. Originally called Habitat in 1988, it was created by LucasArts for Q-Link users on C64 computers. Users could chat, exchange items, and interact with others. Though the game’s world was simple, its use of online avatars and a mix of chat and graphics was groundbreaking. Online graphics in the late 1980s were limited by slow modem speeds (as low as 300 bits per second). Habitat’s graphics were stored on floppy disks, avoiding the need to transfer them over networks.

Hardware

The Commodore 64 uses an 8-bit MOS Technology 6510 microprocessor. This processor is similar to the 6502 but has three-state buses, a different pinout, slightly different clock signals, and other small changes. The C64 has six I/O lines on unused pins of its 40-pin IC package. These lines are used for two purposes: to switch the machine's read-only memory (ROM) in and out of the processor's address space, and to control the datasette tape recorder. The C64 has 64 KB of 8-bit-wide dynamic RAM, 1 KB of 4-bit-wide static color RAM for text mode, and 38 KB available for Commodore BASIC 2.0 when the computer starts. There is 20 KB of ROM, which includes the BASIC interpreter, the KERNAL, and the character ROM. Because the processor can only access 64 KB at a time, the ROM is mapped into memory, leaving 38,911 bytes of RAM (plus 4 KB between the ROMs) available at startup. Most "breadbin" Commodore 64s used 4164 DRAM with eight chips totaling 64 KB of system RAM. Later models, with Assy 250466 and Assy 250469 motherboards, used 41464 DRAM (64K×4) chips, which stored 32 KB per chip (so only two were needed). The 4164 DRAMs are 64K×1, so eight chips are needed to make a full byte; the computer will not work without all of them. The first chip contains Bit 0 for the memory space, the second chip contains Bit 1, and so on.

The C64 checks its RAM when it starts. If a problem is found in the RAM, less memory is available for BASIC programs than the normal 38,911 bytes. If the faulty chip is in lower memory, an error message "OUT OF MEMORY IN 0" appears instead of the usual BASIC startup screen.

The C64 uses a complex memory system. By default, the BASIC ROM is mapped into memory at $A000–$BFFF, and the screen editor (KERNAL) ROM is mapped at $E000–$FFFF. RAM under the system ROMs can be written to but not read back without swapping out the ROMs. Memory location $01 contains a register that controls whether the system ROMs and the I/O area at $D000 are enabled or disabled. If the KERNAL ROM is swapped out, BASIC is also removed. BASIC cannot work without the KERNAL because it often calls KERNAL routines, and part of BASIC's ROM code is in the KERNAL ROM.

The character ROM is normally hidden from the CPU. It can be mapped into $D000–$DFFF, making it visible to the CPU. However, this requires swapping out the I/O registers, so interrupts must first be disabled. Removing I/O from the memory map frees $D000–$DFFF to be used as RAM.

C64 cartridges are mapped into specific ranges in the CPU's address space. Common cartridges that start automatically use a string at $8000 containing "CBM80" followed by the program's start address. Some 1982 cartridges used Ultimax mode, a leftover feature from the failed MAX Machine. These cartridges mapped into $F000, replacing the KERNAL ROM. Using Ultimax mode requires programmers to handle system interrupts. The cartridge port has 16 address lines, allowing access to the computer's full memory if needed. Disk and tape software usually loads at the start of BASIC memory ($0801) and uses a small BASIC command (like "10 SYS(2064)") to jump to the program. Most C64 software loads into BASIC memory and requires the user to type "RUN" after loading.

About 300 cartridges were released for the C64, mainly in its first 2.5 years on the market. After that, most software needed more than 16 KB, so cartridges were no longer practical. One popular expansion was the Power Cartridge, made by Kolff Computer Supplies. It added tools for BASIC, a machine code monitor, a reset button, and fastload routines for faster cassette and disk access. Larger companies like Ocean Software used bank-switched cartridges later in the C64's life to overcome the 16 KB limit.

Commodore did not include a reset button until the CBM-II line, but third-party cartridges had one. A soft reset can be triggered by jumping to the CPU reset routine at $FCE2. Some programs use this as an exit feature, but it does not clear memory.

The KERNAL ROM had three versions. The first was only used in early models with 326298 motherboards and could not detect if the VIC-II chip was NTSC or PAL. The second version was used from late 1982 to 1985. The third version was introduced with the 250466 motherboard (late breadbin models) and used in all C64Cs. The 6510 CPU runs at 1.023 MHz (NTSC) or 0.985 MHz (PAL), slower than some competitors like the Atari 800 (1.79 MHz). Performance can improve slightly by disabling the VIC-II's video output through a register write. This is used by fast loaders and the KERNAL cassette routine to keep standard CPU timing.

The restore key is connected directly to the CPU's NMI line. Pressing it triggers an NMI. The KERNAL checks if the run/stop key is also pressed. If not, it ignores the NMI. Run/stop-restore is a soft reset in BASIC, restoring I/O registers to default settings but not clearing memory or resetting pointers.

Clones and other reuse of the Commodore 64 name

C64 clones are computers that copy the functions of the Commodore 64. In mid-2004, after more than 10 years without being sold, PC maker Tulip Computers (which owned the Commodore brand since 1997) introduced the C64 Direct-to-TV (C64DTV). This was a TV game console that used a joystick and had 30 games stored in its memory. Designed by Jeri Ellsworth, a self-taught computer designer who also created the C-One C64 version, the C64DTV was similar to small game consoles based on the Atari 2600 and Intellivision. The C64DTV was sold on QVC in the United States during the 2004 holiday season.

In 2015, Individual Computers made a Commodore 64-compatible motherboard called the C64 Reloaded. This was a redesigned version of the Commodore 64 motherboard model 250466, with added features. The motherboard is meant to fit into an existing empty C64 or C64C case. Made in limited numbers, some models had special sockets for custom chips. The board included switches to use different versions of the VIC-II and SID chips and could switch between PAL and NTSC video systems. It also had options to choose different memory settings, a reset button on the power switch, and an S-Video port instead of the original TV modulator. The motherboard used a DC-to-DC converter powered by 12 V DC from an adapter, instead of the original Commodore 64 power supply.

In 1998, the Commodore 64 name was used again for the Web.it Internet Computer, a low-powered, Internet-focused PC that ran MS-DOS and Windows 3.1. It used an AMD Élan SC400 chip, had 16 MB of memory, a 3.5-inch floppy disk drive, a 56k modem, and a PC Card. Although it had the Commodore 64 name, it looked different and could only work with the original through included software that mimicked its functions. In 2011, Commodore USA, a company that licensed the Commodore trademark, began selling PC clones called C64x. These had cases similar to the original C64 but used x86 technology and were not compatible with the original Commodore 64.

Several Commodore 64 games were released on the Nintendo Wii’s Virtual Console service in Europe and North America. These games were removed from the service in August 2013.

A British company called Retro Games made two unofficial Linux-based emulation consoles based on the Commodore 64: THEC64 Mini in 2018 and the full-size THEC64 in 2019. Retro Games did not use the Commodore trademark, so the name THEC64 (without a space) was used instead. This also meant the original Commodore key on the keyboard was replaced with a THEC64 key.

THEC64 Mini is a small, decorative version of the Commodore 64 with two USB ports, one HDMI port, and a mini USB connection for power. Its keyboard does not work, and the system is controlled using a included THEC64 joystick or a separate USB keyboard. It uses the VICE emulator, which can also load extra software.

The full-size THEC64 is the same size as the original Commodore 64 and has a working keyboard. It includes features like VIC-20 emulation, two more USB ports, and an improved joystick.

• THEC64 Mini (top) next to an original C64
• Full-size THEC64 in its original box

In December 2025, Commodore International released the Commodore 64 Ultimate. This is a remake of the Commodore 64 using FPGA technology, with added features such as HDMI output and the ability to load software through USB, Wi-Fi, or Ethernet.

Emulators

Commodore 64 emulators include the open source VICE, Hoxs64, and CCS64. An iPhone app was also released with a compilation of C64 ports.

The Commodore PET, introduced in July 2015, was an Android smartphone with Commodore 64 and Amiga emulation built-in.