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Commodore 64

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   8-bit home computer introduced in 1982
   "C64" redirects here. For other uses, see C64 (disambiguation).
   For the hip-hop band, see Commodore 64 (band).

   CAPTION: Commodore 64

   Commodore 64.svg
   C64 hardware
      Manufacturer    Commodore Business Machines (CBM)
          Type        Home computer
      Release date    August 1982; 40 years ago (1982-08)^[1]
   Introductory price US$595 (equivalent to $1,670 in 2021)
      Discontinued    April 1994; 28 years ago (1994-04)
       Units sold     12.5^[2] - 17^[3] million
    Operating system
     * Commodore KERNAL/BASIC 2.0
     * GEOS (optionally)

          CPU MOS Technology 6510/8500
     * @ 1.023 MHz (NTSC version)
     * @ 0.985 MHz (PAL version)

         Memory       64 KB (65,536 bytes) (IEC: KiB) RAM + 20 KB ROM
        Graphics      VIC-II (320 *200, 16 colors, sprites, raster interrupt)
         Sound        SID 6581/8580 (3 * osc, 4 * wave, filter, ADSR, ring)
     * 2 * CIA 6526 (joystick, GPIO/RS-232/keyboard)
     * Power (+5V DC & 9V AC)
     * ROM cartridge
     * Video/audio (RF/A/V)
     * Serial IEEE 488 bus (floppy disk/printer)
     * Digital tape

     * Commodore VIC-20
     * Commodore MAX Machine

     * Commodore 128
     * Amiga

   The Commodore 64, also known as the C64, is an 8-bit home computer
   introduced in January 1982 by Commodore International (first shown at
   the Consumer Electronics Show, January 7-10, 1982, in Las Vegas).^[4]
   It has been listed in the Guinness World Records as the highest-selling
   single computer model of all time,^[5] with independent estimates
   placing the number sold between 12.5 and 17 million units.^[2] Volume
   production started in early 1982, marketing in August for US$595
   (equivalent to $1,671 in 2021).^[6] Preceded by the Commodore VIC-20
   and Commodore PET, the C64 took its name from its 64 kilobytes (65,536
   bytes) of RAM. With support for multicolor sprites and a custom chip
   for waveform generation, the C64 could create superior visuals and
   audio compared to systems without such custom hardware.

   The C64 dominated the low-end computer market (except in the UK and
   Japan, lasting only about six months in Japan^[7]) for most of the
   later years of the 1980s.^[8] For a substantial period (1983-1986), the
   C64 had between 30% and 40% share of the US market and two million
   units sold per year,^[9] outselling IBM PC compatibles, Apple
   computers, and the Atari 8-bit family of computers. Sam Tramiel, a
   later Atari president and the son of Commodore's founder, said in a
   1989 interview, "When I was at Commodore we were building 400,000 C64s
   a month for a couple of years."^[10] In the UK market, the C64 faced
   competition from the BBC Micro and the ZX Spectrum,^[11] but the C64
   was still the second most popular computer in the UK after the ZX
   Spectrum.^[12] The Commodore 64 failed to make any impact in Japan. The
   Japanese market was dominated by Japanese computers, such as the NEC
   PC-8801, Sharp X1, Fujitsu FM-7, and MSX.^[13]

   Part of the Commodore 64's success was its sale in regular retail
   stores instead of only electronics or computer hobbyist specialty
   stores. Commodore produced many of its parts in-house to control costs,
   including custom integrated circuit chips from MOS Technology. In the
   United States, it has been compared to the Ford Model T automobile for
   its role in bringing a new technology to middle-class households via
   creative and affordable mass-production.^[14] Approximately 10,000
   commercial software titles have been made for the Commodore 64,
   including development tools, office productivity applications, and
   video games.^[15] C64 emulators allow anyone with a modern computer, or
   a compatible video game console, to run these programs today. The C64
   is also credited with popularizing the computer demoscene and is still
   used today by some computer hobbyists.^[16] In 2011, 17 years after it
   was taken off the market, research showed that brand recognition for
   the model was still at 87%.^[5]
   [ ]


     * 1 History
          + 1.1 Reception
          + 1.2 Market war: 1982-1983
          + 1.3 1984-1987
          + 1.4 1988-1994
     * 2 C64 family
          + 2.1 Commodore MAX
          + 2.2 Commodore Educator 64
          + 2.3 SX-64
          + 2.4 Commodore 128
          + 2.5 Commodore 64C
          + 2.6 Commodore 64 Games System
          + 2.7 Commodore 65
     * 3 Software
          + 3.1 BASIC
          + 3.2 Alternative operating systems
          + 3.3 Networking software
          + 3.4 Online gaming
     * 4 Hardware
          + 4.1 CPU and memory
          + 4.2 Joysticks, mice, and paddles
          + 4.3 Graphics
          + 4.4 Text modes
               o 4.4.1 Character block animation
               o 4.4.2 Hardware sprites
          + 4.5 Sound
          + 4.6 Hardware revisions
               o 4.6.1 ICs
               o 4.6.2 Motherboard
          + 4.7 Power supply
          + 4.8 Specifications
               o 4.8.1 Internal hardware
               o 4.8.2 Input/output (I/O) ports and power supply
               o 4.8.3 Memory map
               o 4.8.4 Peripherals
          + 4.9 Manufacturing cost
          + 4.10 Clones
          + 4.11 Newer compatible hardware
          + 4.12 Brand reuse
          + 4.13 Virtual Console
          + 4.14 THEC64 and THEC64 Mini
     * 5 Emulators
     * 6 See also
     * 7 Footnotes
          + 7.1 References
          + 7.2 Sources
     * 8 External links


   The Commodore 64 startup screen

   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, named MOS Technology VIC-II (Video Integrated Circuit for
   graphics) and MOS Technology SID (Sound Interface Device for audio),
   was completed in November 1981.^[6] Commodore then began a game console
   project that would use the new chips--called the Ultimax or the
   Commodore MAX Machine, engineered by Yash Terakura from Commodore
   Japan. This project was eventually cancelled after just a few machines
   were manufactured for the Japanese market.^[17] At the same time,
   Robert "Bob" Russell (system programmer and architect on the VIC-20)
   and Robert "Bob" Yannes (engineer of the SID) were critical of the
   current product line-up at Commodore, which was a continuation of the
   Commodore PET line aimed at business users. With the support of Al
   Charpentier (engineer of the VIC-II) and Charles Winterble (manager of
   MOS Technology), they proposed to Commodore CEO Jack Tramiel a low-cost
   sequel to the VIC-20. Tramiel dictated that the machine should have 64
   KB of random-access memory (RAM). Although 64-Kbit dynamic
   random-access memory (DRAM) chips cost over US$100 (equivalent to
   $251.95 in 2021) at the time, he knew that 64K DRAM prices were falling
   and would drop to an acceptable level before full production was
   reached. The team was able to quickly design the computer because,
   unlike most other home-computer companies, Commodore had its own
   semiconductor fab to produce test chips; because the fab was not
   running at full capacity, development costs were part of existing
   corporate overhead. The chips were complete by November, by which time
   Charpentier, Winterble, and Tramiel had decided to proceed with the new
   computer; the latter set a final deadline for the first weekend of
   January, to coincide with the 1982 Consumer Electronics Show (CES).^[6]

   The product was code named the VIC-40 as the successor to the popular
   VIC-20. The team that constructed it consisted of Yash Terakura,^[18]
   Shiraz Shivji,^[19] Bob Russell, Bob Yannes, and David A. Ziembicki.
   The design, prototypes, and some sample software were finished in time
   for the show, after the team had worked tirelessly over both
   Thanksgiving and Christmas weekends. The machine used the same case,
   same-sized motherboard, and same Commodore BASIC 2.0 in ROM as the
   VIC-20. BASIC also served as the user interface shell and was available
   immediately on startup at the READY prompt. When the product was to be
   presented, the VIC-40 product was renamed C64. The C64 made an
   impressive debut at the January 1982 Consumer Electronics Show, 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?'"^[6]^[20] The answer was vertical
   integration; due to Commodore's ownership of MOS Technology's
   semiconductor fabrication facilities, each C64 had an estimated
   production cost of US$135.^[6]


   In July 1983, BYTE magazine stated that "the 64 retails for $595. At
   that price it promises to be one of the hottest contenders in the
   under-$1,000 personal computer market." It described the SID as "a true
   music synthesizer ... the quality of the sound has to be heard to be
   believed", while criticizing the use of Commodore BASIC 2.0, the floppy
   disk performance which is "even slower than the Atari 810 drive", and
   Commodore's quality control. BYTE gave more details, saying the C64 had
   "inadequate Commodore BASIC 2.0. An 8K-byte interpreted BASIC" which
   they assumed was because "Obviously, Commodore feels that most home
   users will be running prepackaged software - there is no provision for
   using graphics (or sound as mentioned above) from within a BASIC
   program except by means of POKE commands." This was one of very few
   warnings about C64 BASIC published in any computer magazines. ^[21]
   Creative Computing said in December 1984 that the 64 was "the
   overwhelming winner" in the category of home computers under $500.
   Despite criticizing its "slow disk drive, only two cursor directional
   keys, zero manufacturer support, non-standard interfaces, etc.", the
   magazine said that at the 64's price of less than $200 "you can't get
   another system with the same features: 64K, color, sprite graphics, and
   barrels of available software". The Tandy/Radio Shack Color Computer
   was the runner up. However, this was only one of twelve categories
   being voted on, depending on the price and what people wanted to do
   with a computer. The same article also said "Although there was no
   single best all-around system, we noted that one system stood out
   because it was mentioned in so many categories. Although many systems
   were mentioned in two categories, just two systems were mentioned in
   three categories, and only one in four categories--the Apple
   Macintosh." Apart from this, the Apple II was the winner in the
   category of home computer over $500, which was the category the
   Commodore 64 was in when it was first released at the price of

Market war: 1982-1983[edit]

   Game cartridges for Radar Rat Race and International Soccer

   Commodore had a reputation for announcing products that never appeared,
   so sought to quickly ship the C64. Production began in spring 1982 and
   volume shipments began in August.^[6] The C64 faced a wide range of
   competing home computers,^[23] but with a lower price and more flexible
   hardware, it quickly outsold many of its competitors.

   In the United States the greatest competitors were the Atari 8-bit 400,
   the Atari 800, and the Apple II. The Atari 400 and 800 had been
   designed to accommodate previously stringent FCC emissions requirements
   and so were expensive to manufacture. Though similar in specifications,
   the two computers represented differing design philosophies; as an open
   architecture system, upgrade capability for the Apple II was granted by
   internal expansion slots, whereas the C64's comparatively closed
   architecture had only a single external ROM cartridge port for bus
   expansion. However, the Apple II used its expansion slots for
   interfacing to common peripherals like disk drives, printers, and
   modems; the C64 had a variety of ports integrated into its motherboard
   which were used for these purposes, usually leaving the cartridge port
   free. Commodore's was not a completely closed system, however; the
   company had published detailed specifications for most of their models
   since the Commodore PET and VIC-20 days, and the C64 was no exception.
   C64 sales were nonetheless relatively slow due to a lack of software,
   reliability issues with early production models, particularly high
   failure rates of the PLA chip, which used a new production process, and
   a shortage of 1541 disk drives, which also suffered rather severe
   reliability issues. During 1983, however, a trickle of software turned
   into a flood and sales began rapidly climbing, especially with price
   cuts from $600 to just $300 (equivalent to $1600 to $800 in 2021).

   Commodore sold the C64 not only through its network of authorized
   dealers, but also through department stores, discount stores, toy
   stores and college bookstores. The C64 had a built-in RF modulator and
   thus could be plugged into any television set. This allowed it (like
   its predecessor, the VIC-20) to compete directly against video game
   consoles such as the Atari 2600. Like the Apple IIe, the C64 could also
   output a composite video signal, avoiding the RF modulator altogether.
   This allowed the C64 to be plugged into a specialized monitor for a
   sharper picture. Unlike the IIe, the C64's NTSC output capability also
   included separate luminance/chroma signal output equivalent to (and
   electrically compatible with) S-Video, for connection to the Commodore
   1702 monitor, providing even better video quality than a composite

   Aggressive pricing of the C64 is considered to have been a major
   catalyst in the video game crash of 1983. In January 1983, Commodore
   offered a $100 rebate in the United States on the purchase of a C64 to
   anyone that traded in another video game console or computer.^[24] To
   take advantage of this rebate, some mail-order dealers and retailers
   offered a Timex Sinclair 1000 (TS1000) for as little as $10 with
   purchase of a C64. This deal meant that the consumer could send the
   TS1000 to Commodore, collect the rebate, and pocket the difference;
   Timex Corporation departed the computer market within a year.
   Commodore's tactics soon led to a price war with the major home
   computer manufacturers. The success of the VIC-20 and C64 contributed
   significantly to the exit from the field of Texas Instruments and other
   smaller competitors.

   The price war with Texas Instruments was seen as a personal battle for
   Commodore president Jack Tramiel.^[25] Commodore dropped the C64's list
   price by $200 within two months of its release.^[6] In June 1983 the
   company lowered the price to $300, and some stores sold the computer
   for $199. At one point, the company was selling as many C64s as all
   computers sold by the rest of the industry combined. Meanwhile, TI lost
   money by selling the TI-99/4A for $99.^[26] TI's subsequent demise in
   the home computer industry in October 1983 was seen as revenge for TI's
   tactics in the electronic calculator market in the mid-1970s, when
   Commodore was almost bankrupted by TI.^[27]

   All four machines had similar memory configurations which were standard
   in 1982-83: 48 KB for the Apple II+^[28] (upgraded within months of
   C64's release to 64 KB with the Apple IIe) and 48 KB for the Atari
   800.^[29] At upwards of $1,200,^[30] the Apple II was about twice as
   expensive, while the Atari 800 cost $899. One key to the C64's success
   was Commodore's aggressive marketing tactics, and they were quick to
   exploit the relative price/performance divisions between its
   competitors with a series of television commercials after the C64's
   launch in late 1982.^[31] The company also published detailed
   documentation to help developers,^[32] while Atari initially kept
   technical information secret.^[33]

   Although many early C64 games were inferior Atari 8-bit ports, by late
   1983 the growing installed base caused developers to create new
   software with better graphics and sound.^[34] It was the only
   non-discontinued, widely available home computer by then, with more
   than 500,000 sold during the Christmas season;^[35] because of
   production problems in Atari's supply chain, by the start of 1984 "the
   Commodore 64 largely has [the low-end] market to itself right now", The
   Washington Post reported.^[36]


     Some of the graphics modes on the 64 are really strange, and they
     have no analogs to the Atari or Apple, like the ability to change
     color of the character basis across the screen. That gave us a lot
     of color capability that had not been exploited.

   -- Craig Nelson of Epyx, 1986^[34]

   With sales booming and the early reliability issues with the hardware
   addressed, software for the C64 began to grow in size and ambition
   during 1984. This growth shifted to the primary focus of most US game
   developers. The two holdouts were Sierra, who largely skipped over the
   C64 in favor of Apple and PC compatible machines, and Broderbund, who
   were heavily invested in educational software and developed primarily
   around the Apple II. In the North American market, the disk format had
   become nearly universal while cassette and cartridge-based software all
   but disappeared. So most US-developed games by this point grew large
   enough to require multi-loading.

   At a mid-1984 conference of game developers and experts at Origins Game
   Fair, Dan Bunten, Sid Meier, and a representative of Avalon Hill said
   that they were developing games for the C64 first as the most promising
   market.^[37] By 1985, games were an estimated 60 to 70% of Commodore 64
   software.^[38] Computer Gaming World stated in January 1985 that
   companies such as Epyx that survived the video game crash did so
   because they "jumped on the Commodore bandwagon early".^[39] Over 35%
   of SSI's 1986 sales were for the C64, ten points higher than for the
   Apple II. The C64 was even more important for other companies,^[40]
   which often found that more than half the sales for a title ported to
   six platforms came from the C64 version.^[41] That year, Computer
   Gaming World published a survey of ten game publishers that found that
   they planned to release forty-three Commodore 64 games that year,
   compared to nineteen for Atari and forty-eight for Apple II,^[42] and
   Alan Miller stated that Accolade developed first for the C64 because
   "it will sell the most on that system".^[43]

   In Europe, the primary competitors to the C64 were British-built
   computers: the Sinclair ZX Spectrum, the BBC Micro, and the Amstrad CPC
   464. In the UK, the 48K Spectrum had not only been released a few
   months ahead of the C64's early 1983 debut, but it was also selling for
   -L-175, less than half the C64's -L-399 price. The Spectrum quickly
   became the market leader and Commodore had an uphill struggle against
   it in the marketplace. The C64 did however go on to rival the Spectrum
   in popularity in the latter half of the 1980s. Adjusted to the size of
   population, the popularity of Commodore 64 was the highest in Finland
   at roughly 3 units per 100 inhabitants,^[44] where it was subsequently
   marketed as "the Computer of the Republic".^[45]

   Rumors spread in late 1983 that Commodore would discontinue the
   C64.^[46] By early 1985 the C64's price was $149; with an estimated
   production cost of $35-50, its profitability was still within the
   industry-standard markup of two to three times.^[6] Commodore sold
   about one million C64s in 1985 and a total of 3.5 million by mid-1986.
   Although the company reportedly attempted to discontinue the C64 more
   than once in favor of more expensive computers such as the Commodore
   128, demand remained strong.^[47]^[48] In 1986, Commodore introduced
   the 64C,^[49] a redesigned 64, which Compute! saw as evidence
   that--contrary to C64 owners' fears that the company would abandon them
   in favor of the Amiga and 128--"the 64 refuses to die".^[50] Its
   introduction also meant that Commodore raised the price of the C64 for
   the first time, which the magazine cited as the end of the
   home-computer price war.^[51] Software sales also remained strong;
   MicroProse, for example, in 1987 cited the Commodore and IBM PC markets
   as its top priorities.^[52]


   By 1988, PC compatibles were the largest and fastest-growing home and
   entertainment software markets, displacing former leader
   Commodore.^[53] Commodore 64 software sales were almost unchanged in
   the third quarter of 1988 year over year while the overall market grew
   42%,^[54] but the company was still selling 1 to 1.5 million units
   worldwide each year of what Computer Chronicles that year called "the
   Model T of personal computers".^[55] Epyx CEO David Shannon Morse
   cautioned that "there are no new 64 buyers, or very few. It's a
   consistent group that's not growing... it's going to shrink as part of
   our business."^[56] One computer gaming executive stated that the
   Nintendo Entertainment System's enormous popularity - seven million
   sold in 1988, almost as many as the number of C64s sold in its first
   five years - had stopped the C64's growth. Trip Hawkins reinforced that
   sentiment, stating that Nintendo was "the last hurrah of the 8-bit

   SSI exited the Commodore 64 market in 1991, after most
   competitors.^[58] Ultima VI, released in 1991, was the last major C64
   game release from a North American developer, and The Simpsons,
   published by Ultra Games, was the last arcade conversion. The latter
   was a somewhat uncommon example of a US-developed arcade port as after
   the early years of the C64, most arcade conversions were produced by UK
   developers and converted to NTSC and disk format for the US market,
   American developers instead focusing on more computer-centered game
   genres such as RPGs and simulations. In the European market, disk
   software was rarer and cassettes were the most common distribution
   method; this led to a higher prevalence of arcade titles and smaller,
   lower-budget games that could fit entirely in the computer's memory
   without requiring multiloads. European programmers also tended to
   exploit advanced features of the C64's hardware more than their US
   counterparts.^[citation needed]

   In the United States, demand for 8-bit computers all but ceased as the
   1990s began and PC compatibles completely dominated the computer
   market. However, the C64 continued to be popular in the UK and other
   European countries. The machine's eventual demise was not due to lack
   of demand or the cost of the C64 itself (still profitable at a retail
   price point between -L-44 and -L-50), but rather because of the cost of
   producing the disk drive. In March 1994, at CeBIT in Hanover, Germany,
   Commodore announced that the C64 would be finally discontinued in
   1995,^[59] noting that the Commodore 1541 cost more than the C64

   However, only one month later in April 1994, the company filed for
   bankruptcy. When Commodore went bankrupt, all production on their
   inventory, including the C64, was discontinued, thus ending the C64's
   11 and a half year production. Claims of sales of 17, 22 and 30 million
   of C64 units sold worldwide have been made. Company sales records,
   however, indicate that the total number was about 12.5 million.^[60]
   Based on that figure, the Commodore 64 was still the third most popular
   computing platform into the 21st century until 2017 when the Raspberry
   Pi family replaced it.^[61] While 360,000 C64s were sold in 1982, about
   1.3 million were sold in 1983, followed by a large spike in 1984 when
   2.6 million were sold. After that, sales held steady at between 1.3 and
   1.6 million a year for the remainder of the decade and then dropped off
   after 1989. North American sales peaked between 1983 and 1985 and
   gradually tapered off afterward, while European sales remained quite
   strong into the early 1990s.^[2]

   The computer's designers claimed that "The freedom that allowed us to
   do the C-64 project will probably never exist again in that
   environment"; by spring 1983 most had left to found Ensoniq.

C64 family[edit]

Commodore MAX[edit]

   Main article: Commodore MAX Machine
   Commodore MAX Machine

   In 1982, Commodore released the Commodore MAX Machine in Japan. It was
   called the Ultimax in the United States and VC-10 in Germany. The MAX
   was intended to be a game console with limited computing capability and
   was based on a cut-down version of the hardware family later used in
   the C64. The MAX was discontinued months after its introduction because
   of poor sales in Japan.^[62]

Commodore Educator 64[edit]

   Main article: Commodore Educator 64
   Commodore Educator 64

   1983 saw Commodore attempt to compete with the Apple II's hold on the
   US education market with the Educator 64,^[63] essentially a C64 and
   "greenscale" monochrome monitor in a PET case. Schools preferred the
   all-in-one metal construction of the PET over the standard C64's
   separate components, which could be easily damaged, vandalized, or
   stolen.^[64] Schools did not prefer the Educator 64 to the wide range
   of software and hardware options the Apple IIe was able to offer, and
   it was produced in limited quantities.^[65]


   Main article: Commodore SX-64

   Commodore SX-64

   Also in 1983, Commodore released the SX-64, a portable version of the
   C64. The SX-64 has the distinction of being the first commercial
   full-color portable computer.^[66] While earlier computers using this
   form factor only incorporate monochrome ("green screen") displays, the
   base SX-64 unit features a 5 in (130 mm) color cathode-ray tube (CRT)
   and one integrated 1541 floppy disk drive. Even though Commodore
   claimed in advertisements that it would have dual 1541 drives, when the
   SX-64 was released there was only one and the other became a floppy
   disk storage slot. Also, unlike most other C64s, the SX-64 does not
   have a datasette connector so an external cassette was not an

  Commodore 128[edit]

   Main article: Commodore 128

   Two designers at Commodore, Fred Bowen and Bil Herd, were determined to
   rectify the problems of the Plus/4. They intended that the eventual
   successors to the C64--the Commodore 128 and 128D computers
   (1985)--were to build upon the C64, avoiding the Plus/4's
   flaws.^[68]^[69] The successors had many improvements such as a BASIC
   with graphics and sound commands (like almost all home computers not
   made by Commodore ^[70]^[71]^[72]), 80-column display ability, and full
   CP/M compatibility. The decision to make the Commodore 128 plug
   compatible with the C64 was made quietly by Bowen and Herd, software
   and hardware designers respectively, without the knowledge or approval
   by the management in the post Jack Tramiel era. The designers were
   careful not to reveal their decision until the project was too far
   along to be challenged or changed and still make the impending Consumer
   Electronics Show (CES) in Las Vegas.^[68] Upon learning that the C128
   was designed to be compatible with the C64, Commodore's marketing
   department independently announced that the C128 would be 100%
   compatible with the C64, thereby raising the bar for C64 support. In a
   case of malicious compliance, the 128 design was altered to include a
   separate "64 mode" using a complete C64 environment to try to ensure
   total compatibility.^[citation needed]

  Commodore 64C[edit]

   Commodore 64C with 1541-II floppy disk drive and 1084S monitor
   displaying television-compatible S-Video

   The C64's designers intended the computer to have a new, wedge-shaped
   case within a year of release, but the change did not occur.^[6] In
   1986, Commodore released the 64C computer, which is functionally
   identical to the original. The exterior design was remodeled in the
   sleeker style of the Commodore 128.^[48] The 64C uses new versions of
   the SID, VIC-II, and I/O chips being deployed. Models with the C64E
   board had the graphic symbols printed on the top of the keys, instead
   of the normal location on the front. The sound chip (SID) was changed
   to use the MOS 8580 chip, with the core voltage reduced from 12V to 9V.
   The most significant changes include different behavior in the filters
   and in the volume control, which result in some music/sound effects
   sounding differently than intended, and in digitally-sampled audio
   being almost inaudible, respectively (though both of these can mostly
   be corrected-for in software). The 64 KB RAM memory went from eight
   chips to two chips. BASIC and the KERNAL went from two separate chips
   into one 16 KB ROM chip. The PLA chip and some TTL chips were
   integrated into a DIL 64-pin chip. The "252535-01" PLA integrated the
   color RAM as well into the same chip. The smaller physical space made
   it impossible to put in some internal expansions like a
   floppy-speeder.^[73] In the United States, the 64C was often bundled
   with the third-party GEOS graphical user interface (GUI)-based
   operating system, as well as the software needed to access Quantum
   Link. The 1541 drive received a matching face-lift, resulting in the
   1541C. Later, a smaller, sleeker 1541-II model was introduced, along
   with the 800 KB^[74] 3.5-inch microfloppy 1581.

  Commodore 64 Games System[edit]

   Main article: Commodore 64 Games System

   Commodore 64 Games System "C64GS"

   In 1990, the C64 was repackaged in the form of a game console, called
   the C64 Games System (C64GS), with most external connectivity
   removed.^[75] A simple modification to the 64C's motherboard was made
   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. Designed to compete with the Nintendo Entertainment System
   and the Sega Master System, it suffered from very low sales compared to
   its rivals. It was another commercial failure for Commodore, and it was
   never released outside Europe. The Commodore game system lacked a
   keyboard, so any software that requires a keyboard could not be used.

  Commodore 65[edit]

   Main article: Commodore 65

   In 1990, an advanced successor to the C64, the Commodore 65 (also known
   as the "C64DX"), was prototyped, but the project was canceled by
   Commodore's chairman Irving Gould in 1991. The C65's specifications
   were impressive for an 8-bit computer, bringing specs comparable to the
   16-bit Apple IIGS. For example, it could display 256 colors on the
   screen, while OCS based Amigas could only display 64 in HalfBrite mode
   (32 colors and half-bright transformations). Although no specific
   reason was given for the C65's cancellation, it would have competed in
   the marketplace with Commodore's lower-end Amigas and the Commodore


   Main article: Commodore 64 software

   In 1982, the C64's graphics and sound capabilities were rivaled only by
   the Atari 8-bit family and appeared exceptional when compared with the
   widely publicized Atari VCS and Apple II. The C64 is often credited
   with starting the computer subculture known as the demoscene (see
   Commodore 64 demos). It is still being actively used in the
   demoscene,^[76] especially for music (its SID sound chip even being
   used in special sound cards for PCs, and the Elektron SidStation
   synthesizer). Even though other computers quickly caught up with it,
   the C64 remained a strong competitor to the later video game consoles
   Nintendo Entertainment System (NES) and Sega Master System, thanks in
   part to its by-then established software base, especially outside North
   America, where it comprehensively outsold the NES.^[citation needed]

   Because of lower incomes and the domination of the Sinclair Spectrum in
   the UK, almost all British C64 software used cassette tapes. Few
   cassette C64 programs were released in the US after 1983 and, in North
   America, the diskette was the principal method of software
   distribution. The cartridge slot on the C64 was also mainly a feature
   used in the computer's first two years on the US market and became
   rapidly obsolete once the price and reliability of 1541 drives
   improved. A handful of PAL region games used bank switched cartridges
   to get around the 16 KB memory limit.


   Main article: Commodore BASIC

   The Simons' BASIC interpreter start-up screen. Note the altered
   background and text colors (vs the ordinary C64 blue tones) and the 8
   KB reduction of available BASIC-interpreter program memory allocation,
   due to the address space used by the cartridge.

   As is common for home computers of the early 1980s, the C64 comes with
   a BASIC interpreter, in ROM. KERNAL, I/O, and tape/disk drive
   operations are accessed via custom BASIC language commands. The disk
   drive has its own interfacing microprocessor and ROM (firmware) I/O
   routines, much like the earlier CBM/PET systems and the Atari 400 and
   Atari 800. This means that no memory space is dedicated to running a
   disk operating system, as was the case with earlier systems such as the
   Apple II and TRS-80.

   Commodore BASIC 2.0 is used instead of the more advanced BASIC 4.0 from
   the PET series, since C64 users were not expected to need the
   disk-oriented enhancements of BASIC 4.0. The company did not expect
   many to buy a disk drive, and using BASIC 2.0 simplified VIC-20 owners'
   transition to the 64.^[77] "The choice of BASIC 2.0 instead of 4.0 was
   made with some soul-searching, not just at random. The typical user of
   a C64 is not expected to need the direct disk commands as much as other
   extensions, and the amount of memory to be committed to BASIC were to
   be limited. We chose to leave expansion space for color and sound
   extensions instead of the disk features. As a result, you will have to
   handle the disk in the more cumbersome manner of the 'old days'."^[78]

   The version of Microsoft BASIC is not very comprehensive and does not
   include specific commands for sound or graphics manipulation, instead
   requiring users to use the "PEEK and POKE" commands to access the
   graphics and sound chip registers directly. To provide extended
   commands, including graphics and sound, Commodore produced two
   different cartridge-based extensions to BASIC 2.0: Simons' BASIC and
   Super Expander 64. Other languages available for the C64 include
   Pascal, C,^[79]^[80] Logo, Forth, and FORTRAN. Compilers for BASIC 2.0
   such as Petspeed 2 (from Commodore), Blitz (from Jason Ranheim), and
   Turbo Lightning (from Ocean Software) were produced. Most commercial
   C64 software was written in assembly language, either cross-developed
   on a larger computer, or directly on the C64 using a machine code
   monitor or an assembler. This maximized speed and minimized memory use.
   Some games, particularly adventures, used high-level scripting
   languages and sometimes mixed BASIC and machine language.

  Alternative operating systems[edit]

   Many third-party operating systems have been developed for the C64. As
   well as the original GEOS, two third-party GEOS-compatible systems have
   been written: Wheels and GEOS megapatch. Both of these require hardware
   upgrades to the original C64. Several other operating systems are or
   have been available, including WiNGS OS, the Unix-like LUnix, operated
   from a command-line, and the embedded systems OS Contiki, with full
   GUI. Other less well-known OSes include ACE, Asterix, DOS/65, and
   GeckOS. A version of CP/M was released, but this requires the addition
   of an external Z80 processor to the expansion bus. Furthermore, the Z80
   processor is underclocked to be compatible with the C64's memory bus,
   so performance is poor compared to other CP/M implementations. C64 CP/M
   and C128 CP/M both suffer a lack of software; although most commercial
   CP/M software can run on these systems, software media is incompatible
   between platforms. The low usage of CP/M on Commodores means that
   software houses saw no need to invest in mastering versions for the
   Commodore disk format. The C64 CP/M cartridge is also not compatible
   with anything except the early 326298 motherboards.^[citation needed]

  Networking software[edit]

   During the 1980s, the Commodore 64 was used to run bulletin board
   systems using software packages such as Punter BBS, Bizarre 64, Blue
   Board, C-Net, Color 64, CMBBS, C-Base, DMBBS, Image BBS, EBBS, and The
   Deadlock Deluxe BBS Construction Kit, often with sysop-made
   modifications. These boards sometimes were used to distribute cracked
   software. As late as December 2013, there were 25 such Bulletin Board
   Systems in operation, reachable via the Telnet protocol.^[81] There
   were major commercial online services, such as Compunet (UK),
   CompuServe (US - later bought by America Online), The Source (US), and
   Minitel (France) among many others. These services usually required
   custom software which was often bundled with a modem and included free
   online time as they were billed by the minute. Quantum Link (or Q-Link)
   was a US and Canadian online service for Commodore 64 and 128 personal
   computers that operated from November 5, 1985, to November 1, 1994. It
   was operated by Quantum Computer Services of Vienna, Virginia, which in
   October 1991 changed its name to America Online and continued to
   operate its AOL service for the IBM PC compatible and Apple Macintosh.
   Q-Link was a modified version of the PlayNET system, which Control
   Video Corporation (CVC, later renamed Quantum Computer Services)

  Online gaming[edit]

   Further information: History of massively multiplayer online games

   The first graphical character-based interactive environment is Club
   Caribe. First released as Habitat in 1988, Club Caribe was introduced
   by LucasArts for Q-Link customers on their Commodore 64 computers.
   Users could interact with one another, chat and exchange items.
   Although the game's open world was very basic, its use of online
   avatars and the combination of chat and graphics was revolutionary.
   Online graphics in the late 1980s were severely restricted by the need
   to support modem data transfer rates as low as 300 bits per second.
   Habitat's graphics were stored locally on floppy disk, eliminating the
   need for network transfer.^[82]


   This section may contain content that is repetitive or redundant of
   text elsewhere in the article. Please help improve it by merging
   similar text or removing repeated statements. (April 2010)

   Block diagram of the C64

  CPU and memory[edit]

   Main article: MOS Technology 6510

   The C64 uses an 8-bit MOS Technology 6510 microprocessor. It is almost
   identical to the 6502 but with three-state buses, a different pinout,
   slightly different clock signals and other minor changes for this
   specific application. It also has six I/O lines on otherwise unused
   legs on the 40-pin IC package. These are used for two purposes in the
   C64: to bank-switch the machine's read-only memory (ROM) in and out of
   the processor's address space, and to operate 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 are available to
   built-in Commodore BASIC 2.0 on startup. There is 20 KB of ROM, made up
   of the BASIC interpreter, the KERNAL, and the character ROM. As the
   processor could only address 64 KB at a time, the ROM was mapped into
   memory, and only 38911 bytes of RAM (plus 4 KB in between the ROMs)
   were available at startup. Most "breadbin" Commodore 64s used 4164
   DRAM, with eight chips to total up 64K of system RAM. Later models,
   featuring Assy 250466 and Assy 250469 motherboards, used 41464 DRAM
   (64K *4) chips which stored 32 KB per chip, so only two were required
   Since 4164 DRAMs are 64K *1, eight chips are needed to make an entire
   byte, and the computer will not function without all of them present.
   Thus, the first chip contains Bit 0 for the entire memory space, the
   second chip contains Bit 1, and so forth. This also makes detecting
   faulty RAM easy, as a bad chip will display random characters on the
   screen and the character displayed can be used to determine the faulty

   The C64 performs a RAM test on power up and if a RAM error is detected,
   the amount of free BASIC memory will be lower than the normal 38911
   figure. If the faulty chip is in lower memory, then an ?OUT OF MEMORY
   IN 0 error is displayed rather than the usual BASIC startup banner. The
   color RAM at $D800 uses a separate 2114 SRAM chip and is gated directly
   to the VIC-II.

   The C64 uses a somewhat complicated memory banking scheme; the normal
   power-on default is to have the BASIC ROM mapped in at
   $A000-$BFFF and the screen editor/KERNAL ROM at $E000-$FFFF. RAM
   underneath the system ROMs can be written to, but not read back without
   swapping out the ROMs. Memory location $01 contains a register with
   control bits for enabling/disabling the system ROMs as well as the I/O
   area at $D000. If the KERNAL ROM is swapped out, BASIC will be removed
   at the same time,^[83]^: 264 ^[84] and it is not possible to have BASIC
   active without the KERNAL (as BASIC often calls KERNAL routines and
   part of the ROM code for BASIC is in fact located in the KERNAL ROM).

   The character ROM is normally not visible to the CPU. It has two
   mirrors at
   $1000 and $9000, but only the VIC-II can see them; the CPU will see RAM
   in those locations. The character ROM may be mapped into $D000-$DFFF
   where it is then visible to the CPU. Since doing so necessitates
   swapping out the I/O registers, interrupts must be disabled first.
   Graphics memory and data cannot be placed at $1000 or $9000 as the
   VIC-II will see the character ROM there instead.

   By removing I/O from the memory map,
   $D000-$DFFF becomes free RAM. The color RAM at $D800 is swapped out
   along with the I/O registers and this area can be used for static
   graphics data such as character sets since the VIC-II cannot see the
   I/O registers (or color RAM via the CPU mapping). If all ROMs and the
   I/O area are swapped out, the entire 64k RAM space is available aside
   for locations $0/$1.

   $C000-$CFFF is free RAM and not used by BASIC or KERNAL routines;
   because of this, it is an ideal location to store short machine
   language programs that can be accessed from BASIC. The cassette buffer
   at $0334-$03FF can also be used to store short machine language
   routines provided that a Datasette is not used, which will overwrite
   the buffer.

   C64 cartridges map into assigned ranges in the CPU's address space and
   the most common cartridge auto starting requires the presence of a
   special string at
   $8000 which contains "CBM80" followed by the address where program
   execution begins. A few early C64 cartridges released in 1982 use
   Ultimax mode (or MAX mode), a leftover feature of the failed MAX
   Machine. These cartridges map into $F000 and displace the KERNAL ROM.
   If Ultimax mode is used, the programmer will have to provide code for
   handling system interrupts. The cartridge port has 16 address lines,
   which grants access to the entire address space of the computer if
   needed. Disk and tape software normally load at the start of BASIC
   memory ($0801) and use a small BASIC stub (e.g., 10 SYS(2064)) to jump
   to the start of the program. Although no Commodore 8-bit machine except
   the C128 can automatically boot from a floppy disk, some software
   intentionally overwrites certain BASIC vectors in the process of
   loading so that execution begins automatically rather than requiring
   the user to type RUN at the BASIC prompt following loading.

   Around 300 cartridges were released for the C64, mostly in the
   machine's first
   2+1/2 years on the market, after which most software outgrew the 16 KB
   cartridge limit. In the final years of the C64, larger software
   companies such as Ocean Software began releasing games on bank-switched
   cartridges to overcome this 16 KB cartridge limit.

   Commodore did not include a reset button on any of their computers
   until the CBM-II line, but there were third-party cartridges with a
   reset button on them. It is possible to trigger a soft reset by jumping
   to the CPU reset routine at
   $FCE2 (64738). A few programs use this as an "exit" feature, although
   it does not clear memory.

   The KERNAL ROM went through three separate revisions, mostly designed
   to fix bugs. The initial version is only found on 326298 motherboards,
   used in the first production models, and cannot detect whether an NTSC
   or PAL VIC-II is present. The second revision is found on all C64s made
   from late 1982 through 1985. The third and last KERNAL ROM revision was
   introduced on the 250466 motherboard (late breadbin models with 41464
   RAM) and is found in all C64Cs. The 6510 CPU is clocked at 1.023 MHz
   (NTSC) and 0.985 MHz (PAL),^[85] lower than some competing systems (for
   example, the Atari 800 is clocked at 1.79 MHz). A small performance
   boost can be gained by disabling the VIC-II's video output via a
   register write. This feature is often used by tape and disk fastloaders
   as well as the KERNAL cassette routine to keep a standard CPU cycle
   timing not modified by the VIC-II's sharing of the bus.

   The Restore key is gated directly to the CPU's NMI line and will
   generate an NMI if pressed. The KERNAL handler for the NMI checks if
   Run/Stop is also pressed; if not, it ignores the NMI and simply exits
   back out. Run/Stop-Restore normally functions as a soft reset in BASIC
   that restores all I/O registers to their power on default state, but
   does not clear memory or reset pointers, so any BASIC programs in
   memory will be left untouched. Machine language software usually
   disables Run/Stop-Restore by remapping the NMI vector to a dummy RTI
   instruction. The NMI can be used for an extra interrupt thread by
   programs as well, but runs the risk of a system lockup or undesirable
   side effects if the Restore key is accidentally pressed, as this will
   trigger an inadvertent activation of the NMI thread.

  Joysticks, mice, and paddles[edit]

   Original Commodore white and black joystick
   Commodore analog paddles
   Commodore mouse
   The DE-9 Atari-style joystick ports
   Commodore's version of the classic Atari joystick, a set of analog
   paddles, a 1350/1351 mouse and the DE-9 Atari-style joystick ports

   The C64 retained the DE-9 joystick Atari joystick port from the VIC-20
   and added another; any Atari-specification game controller can be used
   on a C64. The joysticks are read from the registers at
   $DC00 and $DC01, and most software is designed to use a joystick in
   port 2 for control rather than port 1, as the upper bits of $DC00 are
   used by the keyboard and an I/O conflict can result. Although it is
   possible to use Sega game pads on a C64, it is not recommended as the
   slightly different signal generated by them can damage the CIA chip.
   The SID chip's register $D419 is used to control paddles and is an
   analog input. Atari paddles are electrically compatible with the C64,
   but have different resistance values than Commodore's paddles, which
   means most software will not work properly with them.^[citation needed]
   However, only a handful of games, mostly ones released early in the
   computer's life cycle, can use paddles. In 1986, Commodore released two
   mice for the C64 and C128, the 1350 and 1351. The 1350 is a digital
   device, read from the joystick registers (and can be used with any
   program supporting joystick input); while the 1351 is a true, analog
   potentiometer based, mouse, read with the SID's analog-to-digital


   Main article: MOS Technology VIC-II

   The graphics chip, VIC-II, features 16 colors, eight hardware sprites
   per scanline (enabling up to 112 sprites per PAL screen), scrolling
   capabilities, and two bitmap graphics modes.

   CAPTION: Commodore 64 palette

   Color # Name  Hexadecimal RGB value
   0       Black

   1 White
   2 Red
   3 Cyan
   4 Purple
   5 Green
   6 Blue
   7 Yellow
   8 Orange
   9 Brown
   10 Light Red
   11 Dark-Gray
   12 Mid-Gray
   13 Light Green
   14 Light Blue
   15 Light-Gray

  Text modes[edit]

   The standard text mode features 40 columns, like most Commodore PET
   models; the built-in character encoding is not standard ASCII but
   PETSCII, an extended form of ASCII-1963. The KERNAL ROM sets the VIC-II
   to a dark blue background on power up with a light blue text and
   border. Unlike the PET and VIC-20, the C64 uses "fat" double-width text
   as some early VIC-IIs had poor video quality that resulted in a fuzzy
   picture. Most screenshots show borders around the screen, which is a
   feature of the VIC-II chip. By utilizing interrupts to reset various
   hardware registers on precise timings it was possible to place graphics
   within the borders and thus use the full screen.^[86]

   The two PETSCII character sets of the C64

   The C64 has a resolution of 320 *200 pixels, consisting of a 40 *25
   grid of 8 *8 character blocks. The C64 has 255 predefined character
   blocks, called PETSCII. The character set can be copied into RAM and
   altered by a programmer.

   There are two colour modes, high resolution, with two colours available
   per character block (one foreground and one background) and multicolour
   with four colours per character block (three foreground and one
   background). In multicolour mode, attributes are shared between pixel
   pairs, so the effective visible resolution is 160 *200 pixels. This is
   necessary since only 16 KB of memory is available for the VIC-II video

   As the C64 has a bitmapped screen, it is possible to draw each pixel
   individually. This is, however, very slow. Most programmers used
   techniques developed for earlier non-bitmapped systems, like the
   Commodore PET and TRS-80. A programmer redraws the character set and
   the video processor fills the screen block by block from the top left
   corner to the bottom right corner.

   Two different types of animation are used: character block animation
   and hardware sprites.

    Character block animation[edit]

   The user draws a series of characters of a person walking, say, two in
   the middle of the block, and another two walking in and out of the
   block. Then the user sequences them so the character walks into the
   block and out again. Drawing a series of these and the user gets a
   person walking across the screen. By timing the redraw to occur when
   the television screen blanks out to restart drawing the screen there
   will be no flicker. For this to happen, the user programs the VIC-II
   that it generates a raster interrupt when the video flyback occurs.
   This is the technique used in the classic Space Invaders arcade game.

   Horizontal and vertical pixelwise scrolling of up to one character
   block is supported by two hardware scroll registers. Depending on
   timing, hardware scrolling affects the entire screen or just selected
   lines of character blocks. On a non-emulated C64, scrolling is
   glasslike and blur-free.

    Hardware sprites[edit]

   Sprites on screen in a C64 game

   A sprite is a movable character which moves over an area of the screen,
   draws over the background and then redraws it after it moves. Note this
   is very different from character block animation, where the user is
   just flipping character blocks. On the C64, the VIC-II video processor
   handles most of the legwork in sprite emulation; the programmer simply
   defines the sprite and where they want it to go.

   The C64 has two types of sprites, respecting their colour mode
   limitations. Hi-res sprites have one colour (one background and one
   foreground) and multicolour sprites three (one background and three
   foreground). Colour modes can be split or windowed on a single screen.
   Sprites can be doubled in size vertically and horizontally up to four
   times their size, but the pixel attributes are the same - the pixels
   become "fatter". There are 8 sprites in total and all 8 can be shown in
   each horizontal line concurrently. Sprites can move with glassy
   smoothness in front of and behind screen characters and other sprites.

   The hardware sprites of a C64 can be displayed on either a bitmapped
   (high resolution) screen or, alternatively, on a text mode screen in
   conjunction with fast and smooth character block animation. In
   contrast, software emulated sprites found on systems without support
   for hardware sprites such as the Apple II and ZX Spectrum required a
   bitmapped screen.

   Sprite-sprite and sprite-background collisions are detected in hardware
   and the VIC-II can be programmed to trigger an interrupt accordingly.


   Main article: MOS Technology SID

   The SID chip has three channels, each with its own ADSR envelope
   generator and filter capabilities. Ring modulation makes use of channel
   no. 3, to work with the other two channels. Bob Yannes developed the
   SID chip and later co-founded 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 has become a hit of its own among C64 users. Well-known
   composers and programmers of game music on the C64 are Rob Hubbard,
   Jeroen Tel, Tim Follin, David Whittaker, Chris Huelsbeck, Ben Daglish,
   Martin Galway, Kjell Nordbo/ and David Dunn among many others. Due to
   the chip's three channels, chords are often played as arpeggios,
   coining the C64's characteristic lively sound. It was also possible to
   continuously update the master volume with sampled data to enable the
   playback of 4-bit digitized audio. As of 2008, it became possible to
   play four channel 8-bit audio samples, 2 SID channels and still use

   An example of SID chip generated music

   There are two versions of the SID chip: the 6581 and the 8580. The MOS
   Technology 6581 was used in the original ("breadbin") C64s, the early
   versions of the 64C, and the Commodore 128. The 6581 was replaced with
   the MOS Technology 8580 in 1987. While the 6581 sound quality is a
   little crisper and many Commodore 64 fans say they prefer its sound, it
   lacks some versatility available in the 8580 - for example, the 8580
   can mix all available waveforms on each channel, whereas the 6581 can
   only mix waveforms in a channel in a much more limited fashion. The
   main difference between the 6581 and the 8580 is the supply voltage.
   The 6581 uses a 12 volt supply--the 8580, a 9 volt supply. A
   modification can be made to use the 6581 in a newer 64C board (which
   uses the 9 volt chip). The SID chip's distinctive sound has allowed it
   to retain a following long after its host computer was discontinued. A
   number of audio enthusiasts and companies have designed SID-based
   products as add-ons for the C64, x86 PCs, and standalone or Musical
   Instrument Digital Interface (MIDI) music devices such as the Elektron
   SidStation. These devices use chips taken from excess stock, or removed
   from used computers. In 2007, Timbaland's extensive use of the
   SidStation led to the plagiarism controversy for "Block Party" and "Do
   It" (written for Nelly Furtado).

   In 1986, the Sound Expander was released for the Commodore 64. It was a
   sound module that contained a Yamaha YM3526 sound chip capable of FM
   synthesis. It was primarily intended for professional music

  Hardware revisions[edit]

   Three case styles were used: C64 (top, 1982), C64C (1986, middle) and
   C64G (1987, bottom)

   Commodore made many changes to the C64's hardware during its lifetime,
   sometimes causing compatibility issues.^[90] The computer's rapid
   development, and Commodore and Tramiel's focus on cost cutting instead
   of product testing, resulted in several defects that caused developers
   like Epyx to complain and required many revisions to fix; Charpentier
   said that "not coming a little close to quality" was one of the
   company's mistakes.^[6]

   Cost reduction was the reason for most of the revisions. 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 went through two major redesigns and
   numerous sub-revisions, exchanging positions of the VIC-II, SID and PLA
   chips. Initially, a large portion of the cost was eliminated by
   reducing the number of discrete components, such as diodes and
   resistors, which enabled the use of a smaller printed circuit board.
   There were 16 total C64 motherboard revisions, aimed at simplifying and
   reducing manufacturing costs. Some board revisions were exclusive to
   PAL regions. All C64 motherboards were manufactured in Hong Kong.

   IC locations changed frequently on each motherboard revision, as did
   the presence or lack thereof of the metal RF shield around the VIC-II.
   PAL boards often had aluminized cardboard instead of a metal shield.
   The SID and VIC-II are socketed on all boards; however, the other ICs
   may be either socketed or soldered. The first production C64s, made in
   1982 to early 1983, are known as "silver label" models due to the case
   sporting a silver-colored "Commodore" logo. The power LED had a
   separate silver badge around it reading "64". These machines also have
   only a 5-pin video cable and cannot output S-video. In late 1982,
   Commodore introduced the familiar "rainbow badge" case, but many
   machines produced into early 1983 also used silver label cases until
   the existing stock of them was used up. In the spring of 1983, the
   original 326298 board was replaced by the 250407 motherboard which
   sported an 8-pin video connector and added S-video support for the
   first time. This case design was used until the C64C appeared in 1986.
   All ICs switched to using plastic shells while the silver label C64s
   had some ceramic ICs, notably the VIC-II. The case is made from ABS
   plastic which may become brown with time. This can be reversed by using
   a process known as "retrobright".

   An early C64 motherboard (Rev A PAL 1982)

   A C64C motherboard ("C64E" Rev B PAL 1992)


   The VIC-II was manufactured with 5 micrometer NMOS technology^[6] and
   was clocked at either 17.73447 MHz (PAL) or 14.31818 MHz (NTSC).
   Internally, the clock was divided down to generate the dot clock (about
   8 MHz) and the two-phase system clocks (about 1 MHz; the exact pixel
   and system clock speeds are slightly different between NTSC and PAL
   machines). At such high clock rates, the chip generated a lot of heat,
   forcing MOS Technology to use a ceramic dual in-line 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 dual
   in-line package, which reduced costs substantially, but it did not
   totally eliminate the heat problem.^[6] Without a ceramic package, the
   VIC-II required the use of a heat sink. To avoid extra cost, the metal
   RF shielding doubled as the heat sink 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 originally
   manufactured using NMOS at 7 micrometers and in some areas 6
   micrometers.^[6] The prototype SID and some very early production
   models featured a ceramic dual in-line 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 for
   the two 64 kilobit * 4 bit DRAM chips that replaced the original eight
   64 kilobit * 1 bit ICs. After the release of the Commodore 64C,^[91]
   MOS Technology began to reconfigure the original C64's chipset to use
   HMOS production 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 renumbered to 85xx to reflect the change to HMOS.

   In 1987, Commodore released a 64C variant with a highly redesigned
   motherboard commonly known as a "short board". The new board used the
   new HMOS chipset, featuring a new 64-pin PLA chip. The new "SuperPLA",
   as it was dubbed, integrated many discrete components and
   transistor-transistor logic (TTL) chips. In the last revision of the
   64C motherboard, the 2114 4-bit-wide color RAM was integrated into the

  Power supply[edit]

   Joystick ports, power switch, power inlet

   The C64 used an external power supply, a conventional transformer with
   multiple tappings (as opposed to switch mode, the type now used on PC
   power supplies). It was encased in an epoxy resin gel, which
   discouraged tampering but tended to increase the heat level during use.
   The design saved space within the computer's case and allowed
   international versions to be more easily manufactured. The 1541-II and
   1581 disk drives, along with various third-party clones, also come with
   their own external power supply "bricks", as did most peripherals
   leading to a "spaghetti" of cables and the use of numerous double
   adapters by users.

   Commodore power supplies often failed sooner than expected. The
   computer reportedly had a 30% return rate in late 1983, compared to the
   5-7% the industry considered acceptable.^[92] Creative Computing
   reported four working computers out of seven C64s.^[93] Malfunctioning
   power bricks were particularly notorious for damaging the RAM chips.
   Due to their higher density and single supply (+5V), they had less
   tolerance for an overvoltage condition. The usually failing voltage
   regulator could be replaced by piggy-backing a new regulator onto the
   board and fitting a heat sink on top.^[94]

   The original PSU included on early 1982-83 machines had a 5-pin
   connector that could accidentally be plugged into the video output of
   the computer. To prevent the user from making this damaging mistake,
   Commodore changed the plug design on 250407 motherboards to a 3-pin
   connector in 1984.^[citation needed] Commodore later changed the design
   yet again, omitting the resin gel in order to reduce costs. The
   follow-on model, the Commodore 128, used a larger, improved power
   supply that included a fuse. The power supply that came with the
   Commodore REU was similar to that of the Commodore 128's unit,
   providing an upgrade for customers who purchased that accessory.


    Internal hardware[edit]

     * Microprocessor CPU:
          + MOS Technology 6510/8500 (the 6510/8500 is a modified 6502
            with an integrated 6-bit I/O port)
          + Clock speed: 0.985 MHz (PAL) or 1.023 MHz (NTSC)
     * Video: MOS Technology VIC-II 6567/8562 (NTSC), 6569/8565 (PAL)
          + 16 colors^[95]
          + Text mode: 40 *25 characters; 256 user-defined chars (8 *8
            pixels, or 4 *8 in multicolor mode); or extended background
            color; 64 user-defined chars with 4 background colors, 4-bit
            color RAM defines foreground color
          + Bitmap modes: 320 *200 (2 unique colors in each 8 *8 pixel
            block),^[96] 160 *200 (3 unique colors + 1 common color in
            each 4 *8 block)^[96]
          + 8 hardware sprites of 24 *21 pixels (12 *21 in multicolor
          + Smooth scrolling, raster interrupts
     * Sound: MOS Technology 6581/8580 SID
          + 3-channel^[95] synthesizer with programmable ADSR envelope
          + 8 octaves
          + 4 waveforms per audio channel: triangle, sawtooth, variable
            pulse, noise
          + Oscillator synchronization, ring modulation
          + Programmable filter: high pass, low pass, band pass, notch
     * Input/Output: Two 6526 Complex Interface Adapters
          + 16 bit parallel I/O
          + 8 bit serial I/O
          + 24-hours (AM/PM) Time of Day clock (TOD), with programmable
            alarm clock^[97]
          + 16 bit interval timers
     * RAM:
          + 64 KB, of which 38 KB were available for BASIC programs
          + 1024 nybbles^[83]^: 262 color RAM (memory allocated for screen
            color data storage)^[98]
          + Expandable to 320 KB with Commodore 1764 256 KB RAM Expansion
            Unit (REU); although only 64 KB directly accessible; REU used
            mostly for the 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.

   Creative Micro Designs also produced a 2 MB REU for the C64 and C128,
   called the 1750 XL. The technology actually supported up to 16 MB, but
   2 MB was the biggest one officially made. Expansions of up to 16 MB
   were also possible via the CMD SuperCPU.
     * ROM:
          + 20 KB (9 KB Commodore BASIC 2.0; 7 KB KERNAL; 4 KB character
            generator, providing two 2 KB character sets)

    Input/output (I/O) ports and power supply[edit]

   Commodore 64 ports (from left: Joy1, Joy2, Power, ROM cartridge,
   RF-adj, RF modulator, A/V, Serial 488 bus, Tape, User)

     * I/O ports:^[99]^[better source needed]
          + ROM cartridge expansion slot (44-pin slot for edge connector
            with 6510 CPU address/data bus lines and control signals, as
            well as GND and voltage pins;^[100] used for program modules
            and memory expansions, among others)
          + Integrated RF modulator television antenna output via an RCA
            connector. The used channel could be adjusted from number 36
            with the potentiometer to the left.
          + 8-pin DIN connector containing composite video output,
            separate Y/C outputs and sound input/output. This is a 262DEG
            horseshoe version of the plug, rather than the 270DEG circular
            version. Early C64 units (with motherboard Assy 326298) use a
            5-pin DIN connector that carries composite video and luminance
            signals, but lacks a chroma signal.^[101]
          + Serial bus (proprietary serial version of IEEE-488, 6-pin DIN
            plug) for CBM printers and disk drives
          + PET-type Commodore Datassette 300 baud tape interface (edge
            connector with digital cassette motor/read/write/key-sense
            signals), Ground and +5V DC lines. The cassette motor is
            controlled by a +5V DC signal from the 6510 CPU. The 9V AC
            input is transformed into unregulated 6.36V DC^[102] which is
            used to actually power the cassette motor.^[103]
          + User port (edge connector with TTL-level signals, for modems
            and so on; byte-parallel signals which can be used to drive
            third-party parallel printers, among other things, 17 logic
            signals, 7 Ground and voltage pins, including 9V AC)
          + 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 graphics tablets such as the KoalaPad.
     * Power supply:
          + 5V DC and 9V AC from an external "power brick", attached to a
            7-pin female DIN-connector on the computer.^[104]

   The 9 volt AC is used to supply power via a charge pump to the SID
   sound generator chip, provide 6.8V via a rectifier to the cassette
   motor, a "0" pulse for every positive half wave to the time-of-day
   (TOD) input on the CIA chips, and 9 volts AC directly to the user-port.
   Thus, as a minimum, a 12 V square wave is required. But a 9 V sine wave
   is preferred.^[105]^[106]^[better source needed]

    Memory map[edit]

   Address Size
   [KB] Description
   0x0000 32.0 RAM ^[107]
   0x8000 8.0 RAM Cartridge ROM ^[107]
   0xA000 8.0 RAM BASIC ROM ^[107]
   0xC000 4.0 RAM ^[107]
   0xD000 4.0 RAM   I/O/Color RAM Character ROM ^[107]
   0xE000 8.0 RAM KERNAL ROM ^[107]

   Note that even if an I/O chip like the VIC-II only uses 64 positions in
   the memory address space, it will occupy 1,024 addresses because some
   address bits are left undecoded.^[107]


   See also: Commodore 64 peripherals

     * Commodore 1541 floppy drive
       Commodore 1541 floppy drive
     * Commodore 1541C floppy drive
       Commodore 1541C floppy drive
     * Commodore 1541-II floppy drive
       Commodore 1541-II floppy drive
     * Commodore 1530 Datasette
       Commodore 1530 Datasette
     * Commodore MPS-802 dot matrix printer
       Commodore MPS-802 dot matrix printer
     * Commodore VIC-Modem
       Commodore VIC-Modem
     * Commodore 1351 mouse
       Commodore 1351 mouse
     * Commodore 1702 video monitor
       Commodore 1702 video monitor
     * Commodore 1581 3.5" double-sided floppy drive
       Commodore 1581 3.5" double-sided floppy drive

  Manufacturing cost[edit]

   Vertical integration was the key to keeping Commodore 64 production
   costs low. At the introduction in 1982, the production cost was US$135
   and the retail price US$595. In 1985, the retail price went down to
   US$149 (US$380 today) and the production costs were believed to be
   somewhere between US$35-50 (c.  US$90-130 today). Commodore would not
   confirm this cost figure. Dougherty of the Berkeley Softworks estimated
   the costs of the Commodore 64 parts based on his experience at Mattel
   and Imagic.

   CAPTION: Cost^[6]

   Count Price in 1985 US$ Part
   3 1 ROMs^[6]
   8 1.85 Dynamic RAMs
   4 SID (sound) chip
   4 VIC-II (graphics) chip
   3 RF modulator package
   1-2 6510 8-bit microprocessor
   5 A handful of TTL, buffers, power regulators and capacitors
   10 max Keyboard
   1-2 Printed circuit board
   1-2 Plastic case
   5-10 Power supply and miscellaneous connectors
   1-2 Packaging and manual
   Total: 52.8-61.8

   To lower costs, TTL chips were replaced with less expensive custom
   chips and ways to increase the yields on the sound and graphics chips
   were found. The video chip 6567 had the ceramic package replaced with
   plastic but heat dissipation demanded a redesign of the chip and the
   development of a plastic package that can dissipate heat as well as


   C64 Direct-to-TV

   Clones are computers that imitate C64 functions. In the middle 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 video 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.^[108] By modifying the circuit board, it is possible to attach
   C1541 floppy disk drives, a second joystick, and PS/2 keyboards to
   these units, which gives the DTV devices nearly all the capabilities of
   a full Commodore 64.^[citation needed] The DTV hardware is also used in
   the mini-console Hummer, sold at RadioShack in mid-2005.

   In 2015, a Commodore 64 compatible motherboard was produced by
   Individual Computers. Dubbed the "C64 Reloaded", it is a modern
   redesign of the Commodore 64 motherboard revision 250466 with a few new
   features.^[109] The motherboard itself is designed to be placed in an
   empty C64 or C64C case already owned by the user. Produced in limited
   quantities, models of this Commodore 64 "clone" sport either machined
   or ZIF sockets in which the custom C64 chips would be placed. The board
   also contains jumpers to accept different revisions of the VIC-II and
   SID chips, as well as the ability to jumper between the analogue video
   system modes PAL and NTSC. The motherboard contains several
   innovations, including selection via the RESTORE key of multiple KERNAL
   and character ROMs, built-in reset toggle on the power switch, and an
   S-video socket to replace the original TV modulator. The motherboard is
   powered by a DC-to-DC converter that uses a single power input of 12 V
   DC from a mains adapter to power the unit rather than the original and
   failure-prone Commodore 64 power supply brick.

  Newer compatible hardware[edit]

   As of 2008, C64 enthusiasts still develop new hardware, including
   Ethernet cards,^[110] specially adapted hard disks and flash card
   interfaces (sd2iec).^[111]

  Brand reuse[edit]

   The C64 "Web.it" Internet Computer

   In 1998, the C64 brand was reused for the "Web.it Internet
   Computer",^[112]^[113] a low-powered (even for the time)
   Internet-oriented, all-in-one x86 PC running MS-DOS and Windows 3.1.
   Despite its "Commodore 64" nameplate, the "C64 Web.it" is not directly
   compatible with the original (except via included emulation software),
   nor does it share its appearance. PC clones branded as C64x sold by
   Commodore USA, LLC, a company licensing the Commodore
   trademark,^[114]^[115] began shipping in June 2011.^[116] The C64x has
   a case resembling the original C64 computer, but - as with the "Web.it"
   - it is based on x86 architecture and is not compatible with the
   Commodore 64 on either hardware or software levels.

  Virtual Console[edit]

   Several Commodore 64 games were released on the Nintendo Wii's Virtual
   Console service in Europe and North America only. The games were
   unlisted from the service as of August 2013 for unknown
   reasons.^[citation needed]

  THEC64 and THEC64 Mini[edit]

   THEC64 Mini (top) next to an original C64

   Full-size THEC64 in its original box

   THEC64 Mini is an unofficial Linux-based console that emulates the
   Commodore 64, released in 2018 by UK-based Retro Games. The console
   takes the form of a decorative half-scale Commodore 64 with two USB and
   one HDMI port, plus a mini USB connection to power the system. The
   console's decorative keyboard is non-functional - the system is
   controlled via the included THEC64 joystick, or a separate USB
   keyboard.^[117] It is possible to load new software ROMs into the
   console, which uses emulator x64 (as part of VICE) to run software, and
   has a built-in graphical operating system.^[118]

   The full-size THEC64 was released in 2019 in Europe and Australia, and
   was scheduled for release in November 2020 in the North American
   market. The console and built-in keyboard are built to scale with the
   original Commodore 64, including a functional keyboard. Enhancements
   include VIC-20 emulation, four USB ports, and an upgraded joystick.

   Neither product features any of Commodore's trademarks - the Commodore
   key on the original keyboard is replaced with a THEC64 key, and Retro
   Games can call neither product a "C64" - although the system ROMs are
   licensed from Cloanto Corporation. The consoles can be switched between
   "carousel mode" for accessing the built-in game library, and "classic
   mode" in which the machine operates similarly to a traditional
   Commodore 64. USB storage can be used to hold disk, cartridge and tape
   images for use with the machine.


   Commodore 64 emulators include the open source VICE, Hoxs64,^[119] and
   CCS64. An iPhone app was also released with a compilation of C64 ports.

See also[edit]

     * List of Commodore 64 games
     * History of personal computers
     * IDE64 - P-ATA interface cartridge for the C64
     * SuperCPU - CPU upgrade for C64 and C128



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   Angerhausen, Michael; Becker, Achim; Englisch, Lothar; Gerits, Klaus (1
   December 1983). Hanson, Jeff; Hanson, Kirby; Lee, Arnie (eds.). Anatomy
   of the Commodore 64. A Data Becker book. Translated by Kesten, Detlev.
   Abacus Software. ISBN 978-0916439002. OCLC 1039401881. OL 8337785M -
   via Internet Archive.

     Bagnall, Brian (2005). On the Edge: the Spectacular Rise and Fall of
   Commodore. Variant Press. ISBN 0-9738649-0-7. See especially
   pp. 224-260.

     Tomczyk, Michael (1984). The Home Computer Wars: An Insider's Account
   of Commodore and Jack Tramiel. COMPUTE! Publications, Inc.
   ISBN 0-942386-75-2.

     Jeffries, Ron. "A best buy for '83: Commodore 64". Creative
   Computing, January 1983.

     Amiga Format News Special. "Commodore at CeBIT '94". Amiga Format,
   Issue 59, May 1994.

     Computer Chronicles; "Commodore 64 - Interview with Commodore
   president Max Toy", 1988.

     The C-64 Scene Database; "- Kjell Nordbo/ artist page (bio/release
   history) at CSDb".

     Steil, Michael (December 29, 2008). The Ultimate Commodore 64 Talk.
   25th Chaos Communication Congress (25c3). Berlin. Retrieved December
   28, 2013.

   The Ultimate Commodore 64 Talk. 25th Chaos Communication Congress

External links[edit]

   Wikimedia Commons has media related to Commodore 64.

     * Commodore 64 at Curlie
     * Commodore 64 history, manuals, and photos
     * C64-Wiki (wiki-based encyclopaedia)
     * Extensive collection of information on C64 programming
     * A History of Gaming Platforms: The Commodore 64 from October 2007
     * A Commodore 64 Web Server Using Contiki v2.3*

   Variations on the Commodore 64, archived from the original on May 4,
   2010, retrieved January 24, 2011

     Design case history: the Commodore 64, IEEE Spectrum, March 1985

     Comparing different unit sales analyses

     * v
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   Commodore International


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     * Irving Gould (CEO, 1984-1989)

     * Chuck Peddle
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     * Shiraz Shivji
     * Dave Haynie
     * Albert Charpentier

   Commodore C= logo.svg


     * Amiga Corporation
     * Commodore Business Machines
     * MOS Technology
          + Commodore Semiconductor Group

   Computers dagger

     * KIM-1
     * Commodore PET
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     * Commodore VIC-20
     * Commodore MAX Machine
     * Commodore 64
     * C64GS
     * Commodore SX-64
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     * Commodore Plus/4
     * Commodore 128

   (16-, 32-bit)
     * Amiga 1000
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     * Amiga 2000 (Amiga 2500)
     * Amiga 1500
     * Amiga CDTV
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     * (Amiga 3000UX
     * Amiga 3000T)
     * Amiga 500 Plus
     * Amiga 600
     * Amiga 1200
     * Amiga 4000
     * Amiga 4000T

   PC compatible
     * Commodore PC1
     * Commodore PC5
     * Commodore PC10
     * Commodore PC20
     * Commodore PC30
     * Commodore PC40
     * Commodore PC50
     * Commodore PC60

   Cancelled prototypes
     * Commodore LCD
     * Commodore 900
     * Commodore 65


     * 1351 mouse
     * Commodore 64 peripherals
     * Super Expander
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     * AmigaOS
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     * KERNAL
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   See also

     * Amiga, Inc.
     * Commodore USA
     * Escom AG

   dagger Listed in chronological order by category
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   Authority control: National libraries Edit this at Wikidata
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