Commodore VIC 1001, VIC 20, VC 20

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Commodore VIC 1001, VIC 20, VC 20
Logo from Commodore International

Commodore VIC 20
Commodore International
Sales start and new price
JapanJapanSeptember 1980 for 69,800 yen
(2019 equivalent to 93,274 yen) March 1981 for 299.95 US dollars (2019 equivalent to 828.60 US dollars) October 1981 for £ 199.99 (2019 equivalent to £ 579.70) October 1981 for 899 DM (equivalent to 2019 € 910.20)
United StatesUnited States

United KingdomUnited Kingdom

Cessation of production
June 1984
Main processor
MOS 6502 @ 1.02 MHz (NTSC)
MOS 6502 @ 1.10 MHz (PAL)
RAM ex works
Graphics output
Various text and graphic modes
Color selection from a palette of 8 or 16 colors
Sound output
4 tone generators (output via TV)
Scope of delivery (USA, until 1982)
Computer, power supply unit, antenna cable and crossover, external HF modulator with channel selector switch, instructions, two styrofoam shells, packaging

The first home computer from the US company Commodore International premiered in Japan in September 1980 as the Commodore VIC 1001 . From March 1981 it was also available in the USA - but there under the name Commodore VIC 20 , and in October further sales markets were added. At the instigation of Commodore's German branch, the devices intended for the West German market had previously been renamed Commodore VC 20 . The computer is based on the MOS 6502 microprocessor .

For the first time in the history of home computers, a manufacturer provided an advertising budget in the millions for marketing its home computer and hired a well-known advertising agency. Countless large-format newspaper advertisements and TV spots with prominent brand ambassadors, such as William Shatner , advertised the computer as being very user-friendly and therefore particularly suitable for beginners under the slogan “The Friendly Computer”.

Despite the price war that Texas Instruments started in the home computer industry at the end of 1982 , Commodore was able to hold its own with its technically inferior device. In addition, Commodore claims to be the first manufacturer to exceed the limit of 1 million sold home computers of the same type. After the announcement of the official successor model Commodore 16 in early 1984, Commodore stopped production in June 1984. In total, around 2.5 million copies of the computer had been sold worldwide by mid-1985.

The computer, also known as the “bread box” and “little brother of the C64”, enjoyed great popularity as it enabled many interested parties to enter the “world of colored computers” due to its excellent price-performance ratio. The often criticized inefficient hardware and the expensive upgrades in relation to the computer price were accepted by many users. The computer is considered to be a pioneer for the even greater success model Commodore 64 and an important part of home computer history.


Contrary to the previous company policy of only building high-quality computers with integrated monitors in addition to electronic pocket calculators, Commodore's company founder Jack Tramiel decided in 1979 to manufacture an inexpensive computer "for the masses". Like the video game consoles of its time, the device intended for private use should be connectable to the home television. With the planned color screen output - not a matter of course for many contemporary game consoles and computers - and a particularly low price, it was hoped to be able to take market share from the US competition, and in particular the Apple II . Just like the Apple II, the new home computer was to be equipped with the main processor model 6502 from the manufacturer MOS , which has meanwhile been bought by Commodore .

Development and prototypes

The majority of the Commodore engineers in the development center in the Californian Moorpark stuck to the proven philosophy of an integrated device with monitor in the tradition of PET 2001 , contrary to Tramiel's demand for a cheap computer . Therefore, they initially concentrated on its further development towards a color-capable computer. The economic guidelines of the company management were largely ignored.

Micro PET

Independently of the engineers in California, an employee of the Commodore Semiconductor Group (formerly MOS Technology ) had also been working on a computer since the beginning of 1980 . Such a device should enable larger quantities of the VIC I graphics processor, which has been produced for medical display devices and gaming machines since 1977, to be used, as the search for other customers had previously been unsuccessful. A hand-wired prototype of the computer was presented to Tramiel in May 1980 as a micro-PET . He immediately seized the opportunity to promote the project.

Video interface computer

By the time the world's largest trade fair for entertainment electronics, the Consumer Electronics Show (CES) in June 1980, the developers from California had also designed a computer prototype based on the VIC I, but had already equipped it with the BASIC programming language . The development teams for the two competing pre-series models met for the first time at the trade fair. In doing so, they independently decided to combine the largely functioning inner workings of the Californian device with the presentable housing of the otherwise poorly developed prototype of the Commodore Semiconductor Group. The resulting computer - also in view of the announced price of no more than 300 US dollars - was very popular with the trade fair audience. At the CES, Commodore announced the first official model name Video Interface Computer ( VIC ) and made the decision to bring the device to series production. Work began immediately after CES under the code name Vixen .

Vixen project

After the presentation at the CES, the new computer was to be supplemented with connection options for peripheral devices within just one month and finally brought to series production. Commodore chose the installed technical components mainly for economic reasons. For example, a decision was made in favor of a comparatively inexpensive but slow serial interface for operation with floppy disk drives and printers. Equally helpful in minimizing costs was the use of main memory , which was originally manufactured for the PET 2001, which has since been discontinued, and which could now be reused. A former Commodore employee summarized the resulting device as "PET with VIC chip".

Transfer to production

After the system architecture and most of the hardware components had been developed, the prototype was handed over to Commodore's branch in Japan in July 1980. There, in close cooperation with the US marketing department under the direction of Michael Tomczyk, all the work that was still to be carried out was carried out in order to make the device user-friendly and to ensure smooth production in the company's own Japanese factory. Especially with regard to the inferior keyboards of the more expensive competing computers, those responsible decided to equip the device with a professional typewriter keyboard. It was also hoped that potential buyers would be able to overlook the otherwise comparatively low performance of the computer more easily. Production in Japan finally started in September 1980, initially with a daily output of around 100 computers.


In the spring of 1980, Commodore's marketing department gave the device, which was still under construction at the time, the image of a user- and family-friendly computer (English slogan and brand name The Friendly Computer ) in order to reduce the fear of contact with computers, which was often present at the time . With the emerging Japanese computer industry in view, Tramiel decided at the same time, contrary to the original plans, to initially concentrate all resources and efforts on sales in Japan. With this strategic decision he intended to put the long-term planning Japanese manufacturers with the cheap computers in their own country under pressure and thus prevent them from expanding into the USA. The unrivaled low sales price only served as a purchase incentive for quick customer loyalty, especially for computer beginners. Rather, Commodore's business model relied on the subsequent, much more profitable sales of accessories and software, because the computer alone was hardly useful. In parallel to the preparations for production, Commodore had therefore also initiated the construction of extensions and the provision of peripheral devices.

VIC 1001

The name Commodore VIC 1001 chosen for sales in Japan goes back to employees there. The number after it placed the new computer in a row with the PET 2001, which was also sold in Japan and whose reputation it was intended to profit from. On the day of the premiere in September 1980 , around 1200 orders were received at the premiere location, a Tokyo department store - an unexpected amount of this magnitude. In addition to the low price of 69,800 yen, this successful start was not least due to the software offering that was launched at the same time - Commodore had previously licensed and ported numerous popular arcade classics for the new computer. The publication of the device was accompanied by an advertising campaign in the Japanese print media. Full-page advertisements also presented the VIC 1001 as a computer, the use of which extends far beyond entertainment purposes, as it can be expanded in many ways and thus offers something for every taste and budget.

VIC 20 and VC 20

After the first signs of paralysis in the Japanese computer industry, Commodore decided in September 1980 to also market the computer internationally. This was followed by the official announcement of the now Commodore VIC 20 device in the Four Seasons in New York on September 30, 1980 . At the same time, an advertising campaign was launched in the USA and the home computer was presented at smaller national computer fairs in the months that followed. Only a little later, Commodore presented the device at the CES in January 1981 and made it known to an international specialist audience. During the fair, the high number of around 4,000 pre-orders was made for the time, whereupon Tramiel pushed the start of global production. After the manuals were completed in early January, the first US sales of relabeled computers of Japanese production followed, which had meanwhile reached a daily output of about 400 computers. The VIC 20 was initially sold exclusively through authorized Commodore dealers at a price of $ 299.95.

In Europe, Commodore first presented the computer at the Hanover Fair in April 1981, where the variant of the VIC 20 intended for West Germany could also be seen. Due to the possible offensive pronunciation of the word VIC, this had been renamed Commodore VC 20 at the instigation of the German branch . New product code VC gave German employees based on the very popular brand VW of Volkswagen also an entirely new meaning, namely that of a two-letter word for people computer - a computer for the masses. The official presentation of the VIC 20 in Great Britain took place a little later in mid-June at the 2nd International Commodore PET Show in London. Shortly before, Commodore had already started accepting US trade orders at Summer CES.

Production and delivery were delayed in both America and Europe due to numerous problems. In the USA, technical enhancements to ensure electromagnetic compatibility and color generation were necessary, in Europe adjustments to the power supply units and the image output. While the first US devices produced in Santa Clara, California, were available nationwide in March 1981, the manufacture of computers intended for Europe did not start until the summer of 1981 in Braunschweig, West Germany. In October, the computer was finally available in West Germany for DM 899 and in Great Britain for DM 199 .99 pounds sterling to be purchased. In the other European countries supplied, sales did not begin until November. In Japan, Commodore was already selling the VIC 1001 at a rate of 10,000 units per month.

Mass marketing

While the supply started in Europe, Commodore consistently expanded the worldwide advertising campaign in close cooperation with the renowned New York advertising agency Kornhauser & Calene . With the help of the multi-million dollar advertising budget - a novelty in home computer history - large numbers of full-page advertisements were placed in well-known trade magazines and regional commercials were produced. In the USA, for example, the popular actor William Shatner was specifically chosen as Commodore's brand ambassador. Thanks to Shatner, who became famous for playing the commander of Starship Enterprise , the VIC 20 was given the promotional image of a futuristic high-tech device in addition to its advertised user-friendliness.

At the end of 1981, Commodore began delivering to the US supermarket chain K-Mart , bringing pure mass marketing ever closer. As production increased - the factories were now producing thousands of devices a day - other large American retail companies such as Sears , Toys “R” Us , Musicland and JC Penny were added. Europe, and in particular Great Britain, suffered from delivery bottlenecks, for which Commodore opened a factory in Northamptonshire, England, at the end of the year. By the end of 1981, Commodore had sold around 100,000 of the inexpensive computers worldwide.

Later revisions and accessories

Despite numerous tests, around 100,000 devices from the first production series showed considerable design defects. In addition to failures due to overheating, there were sometimes slight burns on the fingers of users because the plug-in module slot, which was also used for heat dissipation, became too hot. Initially, Commodore made do with rather cosmetic changes to the case to improve ventilation. But only a revision of the circuit board was able to solve the problems to a satisfactory degree.

The computers built from 1982 onwards received a completely revised and reduced circuit board, mainly to simplify the production process and save costs. At the same time, the engineers relocated the heat-intensive voltage regulation previously housed in the computer case to the external power supply unit, which finally eliminated the overheating problems. At the same time, these new models - unofficially referred to as cost reduced - with a modernized nameplate.

At the beginning of January 1982, Commodore presented further additions to its first home computer at the CES, including the Commodore VIC 1540 floppy disk drive and extensive software, largely produced in-house. To underline the advertised versatility of the computer, a particularly inexpensive modem for remote data transmission was added to the product range in March 1982. At the same time, Commodore created appropriate framework conditions for its use in the USA: Contracts with large telecommunications service providers such as Compuserve made it possible to access a wide range of offers such as the online magazine Commodore Information Network .

In the spring of 1982, in the face of emerging competition, they were forced to an initial price reduction for the computer, whereupon the recommended retail price in the USA fell to about 240 US dollars. Only a little later, Commodore began to expand the distribution of home computers to department store chains in Europe and especially in Great Britain. According to Tramiel, Commodore sold more home computers worldwide by the summer of 1982 than Apple Inc. had in all previous years.

Home computer wars and bundle offers

After the VIC 20 had established itself as a fixture on the international home computer market within a year, other manufacturers saw their sales markets increasingly threatened. Texas Instruments responded in September 1982 with a drastic discount on its own TI-99 / 4A home computer . This should deprive Commodore's device of its greatest advantage - its previously unattainable low price. Originally priced at $ 300, the TI-99 / 4A was now available for $ 199. The price of the VIC 20 had been undercut by 40 US dollars. However, Commodore responded that same day by lowering the price of the VIC to $ 199.95. Despite the subsequent ruinous price wars in the home computer industry ("home computer wars"), Commodore announced at the Winter CES in January 1983 that it was the first manufacturer to have sold 1 million home computers of the same type. In West Germany, for example, there were around 60,000 devices. These sales figures were made possible not least by the daily production output, which has now increased to 9,000 devices.

In the wake of the sales success - and also with regard to the promotion of the second home computer and premium model Commodore 64 , which appeared at the end of 1982 - the price of the computer was initially reduced to 125 US dollars and then to 99 US dollars from January 1983. There were also numerous bundled offers with accessories and software. For example, the VIC 20 was available in Great Britain from June 1983, complete with a datassette and five software cartridges, for £ 139. In West Germany, the VC 20 could be purchased in the Christmas business of the same year with a Datassette, four games and a matching sports bag for 498 DM. With all these sales-promoting measures, Commodore was able to sell 2 million computer copies as the first manufacturer. In 1984, the suggested retail price finally dropped to a low of $ 79 without Commodore incurring any losses - the actual manufacturing cost of the computer was estimated at less than $ 60 by the contemporary trade press.

Cessation of production

After the announcement of the official successor models Commodore 16 and the Commodore 116 intended exclusively for West Germany, Commodore ceased production of the VIC in June 1984. From then on, activities were limited to the sale of pre-produced devices. Together with these extensive stocks, Commodore probably sold a total of 2.5 million VIC computers worldwide, 1.5 million of them in the USA alone and about 250,000 in West Germany.

Modern replicas

The simple architecture of the system and extensive documentation from the manufacturer enable the miniaturized replica of the electronics with today's technical means with at the same time manageable effort. Such a modern realization took place for the first time in 2008 - as with other home computer systems - as an implementation on a programmable logic circuit ( FPGA ) together with an embedding system .

Technical details

The housing of the computer contains a single circuit board with all electronic components, the peripheral connections, the external system bus for expansions, the screen output and, in the devices produced up to 1982, the voltage control for the external power supply unit. A later revision outsourced the heat-intensive voltage regulation to the external power supply and the VIC chip was given a metal housing for shielding.

Commovic20mb26049 (retouched) .jpgArbeitsspeicher (SRAM) Eingabe-/Ausgabe-Bausteine (MOS 6522) Ansteuerungselektronik Stiftleiste Anschluss für Datasette Anwenderport (Userport) Audio-/Video-Ausgang für den Anschluss eines Monitors (z. B. VC-1701) oder eines Fernsehgerätes Anschlussbuchse für Diskettenlaufwerke und Drucker (seriell) Aufnahmeschacht für Steckmodule (Software, Erweiterungen) Anschlussbuchse für Netzteil Betriebsschalter Anschlussbuchses für Joystick (z. B. VC-1311), Lightpen, Paddles (VC-1312) oder eines Grafiktabletts Elektrolytkondensator Ansteuerungselektronik Ansteuerungselektronik Video Interface Chip (VIC, MOS 6560) Festwertspeicher Ansteuerungselektronik Ansteuerungselektronik Ansteuerungselektronik Hauptprozessor (MOS 6502) Festwertspeicher Festwertspeicher Schmelzsicherung Leistungstransistor der Spannungsregelung mit Kühlblech Betriebsleuchte
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Main board of the computer in the version produced up to 1982 with internal voltage regulation and without metal shielding of the VIC. Hover over the individual components with the mouse pointer to identify them and click for further information.

Main processor

The system architecture is based on the 8-bit microprocessor MOS 6502. The CPU can access an address space of 65536 bytes , which also defines the theoretically possible upper limit of the main memory of 64 KB. The system clock for PAL devices is 1.10  MHz , for those with NTSC output it is 1.02 MHz.

Special module VIC

In order to generate graphics and sound, Commodore's first home computer uses a special, highly integrated electronic component, the video interface controller ( VIC for short ). It takes the data required to generate the audiovisual output from the working and read-only memory of the computer. The different television standards ( NTSC , PAL ) are essentially implemented by different versions of the VIC: the MOS 6560 was installed in NTSC computers for the Japanese and American markets , in those for PAL systems in Europe, for example, the MOS 6561 . In addition, the VIC is also used to read out paddle controllers and to determine the position of a light pen.


Programming screen with a resolution of 22 × 23 characters with 8 × 8 pixels each

With the VIC, a total of 200 image lines with 192 pixels each can be output on the television set or monitor. However, it does not make sense to use all of the pixels because the curvature of contemporary picture tubes leads to disruptive distortions in their edge areas. Because of this, the computer's system software supports only a smaller display area. For this rectangular section, Commodore chose the size of 176 horizontal and 184 vertical pixels. These seemingly arbitrary dimensions are due to the exclusive use of font graphics, which in turn subdivide the screen into lined-up blocks - the characters - of 8 × 8 or 8 × 16 pixels. This type of screen organization is particularly noticeable in the case of repetitive dot patterns, such as those that occur when displaying text, due to the low memory requirement.

The contents of the maximum 256 definable characters, which can be rasterized letters or parts of a graphic , for example , are loaded by the VIC either from the read-only memory or the main memory. In addition, each character can be assigned color values ​​from a palette of 8 or 16 colors that have to be previously stored in the color memory and in the control registers of the VIC. This data in turn can be processed in different ways by the VIC, resulting in different display modes with different resolutions and color options per character. The editing screen provided by the computer for programming in BASIC, for example, consists of a total of 22 × 23 characters, each with two colors. More advanced programming techniques allow the vertical mixing of the character set and color data interpreted differently by the VIC.


The VIC chip has three separate tone generators to generate and output tones. The first is used to generate lower, the second medium and the third high tones. No individual volume settings are possible for the respective channels, but the same volume value can be assigned to all of them. In addition, there is a special generator in the VIC chip that provides uniformly distributed random numbers ( white noise ), which can also be used to generate noises such as explosions in games.

Memory allocation, working and read-only memory

In Commodore's first home computer, the address space that can be addressed by the CPU and VIC is segmented into different sections of different sizes. For practical reasons, it is common for their addresses instead of decimal notation , the hexadecimal to use. It is usually preceded by a $ symbol to make it easier to distinguish. The addresses from 0 to 65535 in decimal notation correspond to addresses $ 0000 to $ FFFF in the hexadecimal system.

The computer was shipped from the factory with 5 KB of RAM, which occupies the segments $ 0000 to $ 03FF and $ 1000 to $ 1FFF. The 1024 bytes of the first region are doing the operating system and the BASIC - interpreter used to deposit required for the computer operating values. If the 3 KB extension VIC 1210 offered by Commodore is plugged in, then its main memory ranges from $ 0400 to $ 1FFF. The adjoining address range up to $ 7FFF is available for further working memory to be upgraded, which, however, cannot be used by the VIC chip. The character set for the image display is stored in the read-only memory, which extends from $ 8000 to $ 8FFF. The addresses of the electronic circuit for input / output as well as those for the VIC special component are located between $ 9000 and $ 912F. The memory provided for storing the color information is located either in the range from $ 9400 to $ 95FF or from $ 9600 to $ 97FF, depending on the configuration of the system. The content of ROM plug-in modules is displayed between $ A000 and $ BFFF. The program routines of the BASIC interpreter and the operating system ("Kernal") contained in the system ROM range from $ C000 to $ DFFF or $ E000 to $ FFFF.

Input and output, interfaces

Connections to the outside world are a controller socket for connecting various input devices, an output for the monitor or RF modulator to the television, the user port, a data cassette connection, the expansion slot for the use of plug-in modules and a socket for the proprietary serial interface ( Serial Input Output , SIO for short ) is available. The latter is used to operate appropriately equipped "intelligent" peripheral devices with identification numbers. A simplified and Commodore-specific variant of the IEEE-488 transmission protocol is used. Printer, diskette drives, and other devices with two SIO jacks can "so concatenated be connected". One of the two sockets is used to communicate between the device and the computer and the remaining socket is used to connect and manage another device. The standard interfaces RS-232C (serial) and Centronics (parallel) used in many other contemporary computer systems are provided by interface units that can be purchased separately.

Commovc20side5580-01 (retouched) .jpgAnschlussbuchse für Joystick, Lightpen, Maltablett und Paddles Ein-/Ausschalter Betriebsleuchte Anschlussbuchse für das externe Netzteil
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External RF modulator  
Commovc20back-01 (retouched) .jpgAudio-/Video-Ausgang für den Anschluss eines Monitors oder des externen HF-Modulators zum Betrieb an einem Fernsehgerät Buchse der seriellen Schnittstelle zum Anschluss eines Diskettenlaufwerks oder Druckers Betriebsleuchte Erweiterungssteckplatz zum Beispiel für Speicherzusätze, Spielmodule oder Baugruppenträger Anschluss für Datassetten Userport beispielsweise zum Anschluss des VIC-Modems
About this picture
To identify the individual components / connections, hover over them with the mouse pointer
and click for further information if necessary.

Extensions and peripherals

Because of its minimalist hardware equipment, the computer was only suitable for processing the simplest tasks when it was released. More ambitious projects and graphical applications required upgrades, for example of the main memory. Such extensions to expand the system were available both from Commodore and from numerous third-party manufacturers. The model names of Commodore's products are based on the Japanese name of the computer VIC 1001 , also in international sales . The last digit 1 characterizes the computer as the basic device. Expansions and peripheral devices are given sequential numbers such as 1020 , etc. The majority of external expansions are connected to the expansion port of the computer, while peripheral devices such as mass storage devices and printers are often connected to the serial port. An exception is the modem, which is operated using the parallel interface of the computer, the user port.


The computer only has a single expansion slot and can therefore only accommodate a single expansion at the factory. A subrack is also required so that additional RAM and plug-in module-based software, but also special peripheral devices, can be used at the same time. After connecting such a device to the expansion slot of the computer, several slots and corresponding control electronics are available for the actual expansions.

Among the best-known subracks are the models VIC 1010 and VIC 1020 ( called VC 1020 in West Germany ) with six expansion slots each, offered by Commodore from the beginning of 1982 . Third-party manufacturers also brought corresponding devices onto the market around the same time. In the UK, for example, Arfon Microelectronics Ltd. the VIC Expansion Unit and a little later also Arfon Micro . Both the VIC 1020 and the systems from Arfus, thanks to their robust construction, also served as bases for an eye-friendly, elevated positioning of image devices. In West Germany, Data Becker began selling its System 19 extension box with seven slots, which was intended more for a professional environment . The prices for the expansion systems available in West Germany ranged in 1982 from 500 DM for Commodore's unequipped VC 1020 to 11,000 DM for a fully expanded System 19.

Plug-in accessories

With the factory-installed main memory with a capacity of only 5 KB, it was hardly possible to use the computer sensibly. Commodore itself offered corresponding external expansions for the main memory with up to 16 KB in the form of plug-in modules that found their place in the expansion slot or in the subrack. The storage capacities of the extensions from third-party manufacturers, which are also often designed as plug-in modules, reached up to 64 KB.

For programming and for the sensible use of application programs, it was necessary, in addition to increasing the working memory, to increase the number of displayable characters per screen line from the factory 22 to 40 or in special cases up to 80. Commodore itself did not publish any corresponding hardware extensions, but third-party manufacturers brought a large number of them onto the market from 1982 onwards. These extensions were often combined with additional memory. In addition, various graphics extensions had their own read-only memory with additional BASIC commands for easy use of the improved graphic capabilities.

A third group of extensions enables the operation of devices and programs that were not originally designed for the computer. For example, the VIC 1112 interface module brought out by Commodore allows the connection of some printers and floppy disk drives from Commodore's PET series of computers.

Mass storage

In the early 1980s, cassette recorders and floppy disk drives were the main sources of data backup for home computers, while hard drives and removable disk drives were increasingly being used for personal computers in the professional environment . The cheapest variant of data recording using compact cassettes generally has the disadvantage of lower data transfer rates and thus long loading times, whereas the faster and more reliable floppy and disk drives were much more expensive to purchase. When Commodore's first home computer was released, he only had cassette recorders as mass storage devices.

In contrast to other contemporary home computers such as the Tandy TRS-80 or the Sinclair ZX81 , the first home computer from Commodore cannot be operated with standard cassette recorders to store data ex works . Rather, he needs a device that is tailored to his special cassette socket, such as the C2N program recorder . In contrast to other contemporary home computer systems, the reliability is higher due to data blocks written twice, but the average data transfer rate of 300  bit / s and the maximum capacity of 30 KB per C30 compact cassette are significantly lower. Software-based changes to the recording format , such as those made available by Rabbit , Arrow and Turbo Tape , published in 1985, provided a solution. As with the Commodore 1531 Datassette, which was released later, data could be loaded and saved at about the same speed as with a floppy disk drive.

A suitable floppy disk drive, i. H. Commodore first presented a device adapted to Commodore's SIO interface at the Winter CES 1982. Due to technical problems, the device called VIC 1540 or VC 1540 was only available in spring 1982. With this floppy disk drive, 5¼ ″ floppy disks can be written on one side in single density with 690 sectors of 256 bytes each. 174.848 bytes of data can be saved per diskette. The data transfer rate is very low due to faulty peripheral components in the computer and reaches transfer rates of around 8 KB per 25 seconds (around 330 bit / s). Despite the numerous deficiencies of the device, which was initially very expensive at 595 US dollars (396 British pounds, 1798 DM), the demand was much greater than the number of devices provided by Commodore. For this reason, very few software manufacturers decided to also publish their programs in diskette format. The floppy disk drive Commodore VIC 1541 , which was released later for the Commodore 64, can be used with Commodore's first home computer without restrictions.

Input and output devices, remote data transmission

In addition to the keyboard with a total of 66 keys including four function keys, various devices, mainly to be connected to the joystick port, are available for input. These include joysticks from various manufacturers, rotary controls, light pens and graphics tablets from ChalkBoard and Koala Technologies Corp.

Text and graphics can be output both on a monitor and on a television set via an RF modulator. The needle-based printer models VIC 1515 and VIC 1525 , which differ from one another technically essentially only in terms of the system software and the type of paper feed, are used for writing . Third-party printers can only be operated with the help of appropriate extensions, as Commodore's first home computer does not have the appropriate standard interfaces.

To underline the advertised versatility, in the spring of 1982 Commodore presented a 300 baud modem for remote data transmission that was unrivaled at just under 110 US dollars and was unrivaled for US users . At the same time, Commodore created appropriate framework conditions for the sensible use of the device called VIC Modem 1600 . Contracts with large telecommunications service providers such as CompuServe allowed users to call up a wide variety of data, for example through the online magazine Commodore Information Network . So that the modem could be used, it was necessary to upgrade the computer with additional RAM.


As with other home computers of the 1980s, commercial additional software was also sold on various data carriers. The inexpensive compact cassettes, particularly popular with game manufacturers, were, however, very prone to errors due to the high mechanical stress on the magnetic tape, and their use was often associated with long loading times. In addition, certain operating modes, such as relative addressing, which is advantageous for operating databases, are not possible with datasettes. In the case of the plug-in modules, which are much more expensive to manufacture, the programs contained therein were available immediately after switching on the computer, which was a great advantage in particular for system software and frequently used applications. The range of programs for Commodore's first home computer includes not only the selection of commercial programs sold by Commodore but also software ( listings ) developed by third-party manufacturers and published in magazines and books .

System programs and BASIC

After the computer has been switched on, it is first tested for the presence of a ROM plug-in module with executable content. If this is not available, the computer is configured for operation with the BASIC interpreter, which is the responsibility of the operating system housed in the read-only memory . The 39 subroutines of this system program, also known as kernal , control various processes such as the implementation of input and output operations with connected peripheral devices and memory management; the start addresses of the individual subroutines are summarized in a jump table in order to maintain compatibility with later operating system revisions. Once the initialization has been completed, the editing screen is output with a switch-on message and a flashing cursor on the image unit. The computer is now ready for programming in BASIC or for loading programs. The Commodore BASIC 2.0 programming language used is largely identical to that of Commodore's PET and CBM office computer series.

Application programs and games

In addition to the BASIC programming language for creating your own applications, the range of programs only includes a small selection of ready-made commercial application software compared to other home computers. By far the largest part of the both commercial and freely available software for Commodore's first home computers are the games.

The first games were already available in September 1980 with the premiere of the VIC 1001. These were licensed editions of well-known arcade classics such as Space Invaders , Galaxian , Night Driver , Rally-X , Lunar Lander and Pac-Man . Commodore's managers in Japan had previously commissioned the external software manufacturer HAL Laboratories to port them as plug-in module versions . Shortly after the winter CES in early 1981, several titles were added for the US market, including the games Cosmic Jailbreak and Draw Poker programmed in BASIC . Further implementations of arcade games for plug-in modules followed only a little later. In addition, Commodore signed a license agreement with Scott Adams to port numerous adventure games. At the Summer CES in June 1981, Commodore was able to present a large number of games to the world in addition to its home computer. Due to licensing problems with Atari and Bally Midway , many of the entertainment programs went on sale with different names or changed graphic content, including a. as VIC Invaders , Midnight Drive and Jupiter Lander . In the course of 1981, further home conversions of well-known arcade classics such as Omega Race , Gorf and Clowns followed , for which Commodore's own development department was responsible. Due to the comparatively low price of 29.95 to 39.95 US dollars and successful machine implementations, many games developed into bestsellers. The software department became Commodore's most profitable line of business.

In view of the high number of computer sales, third-party manufacturers also joined in the software production. Over 100 companies - including well-known US manufacturers such as Atari , Broderbund , Epyx , Parker Brothers , Sega and Sierra On-Line - published games such as Choplifter , Lode Runner and Miner 2049er . In West Germany, Kingsoft mainly supplied the VC 20 with software. A total of 530 commercial programs had appeared by the end of 1983, including 35 applications, 30 learning titles and 15 programming aids. Commodore alone published 106 titles. The majority of the programs appeared on cassette, about 100 titles on cartridge.



A VIC 20 and its owner (1984).
A VIC 20 in a private science project (1986).

Shortly after its appearance, the western trade press consistently classified the computer as a hobby device. The performance of the computer is in the lower range and can best be compared with that of the Atari 400 and the Tandy TRS-80 Color Computer . However, the VIC 20 would stand out from the competition with its incomparably low price, good workmanship and ease of use. In turn, it differs from video game consoles, which are roughly the same price, in that it has the additional option of programming, which makes it very interesting.

Just like the British computer magazine Your Computer , the US press particularly praised the high-quality typewriter keyboard. It puts all of the competition's membrane and rubber keyboards in the shade and is in no way inferior to those of professional computers. In addition, there is excellent documentation that briefly and clearly explains the possibilities of the device to the user, which is not a matter of course in the more technology-oriented home computer area.

In addition to a few small things, the limited display of only 22 characters per line and the very small working memory of 5 KB were criticized. Professional work is difficult to do with the VIC 20. All other competing devices offer more, but are also much more expensive. Due to its expandability and expandability, the VIC 20 could also reach the lower limit of the performance of professional computers - but only a small consolation in view of the associated high upgrade costs.

All in all, the excellent price-performance ratio made the color-capable computer one of the best devices on the international home computer market in 1981. The high-circulation magazine Compute! For example, summarizes his device test with the words "The VIC 20 computer is unexcelled as a lost-cost, consumer oriented computer." (German "The cheap computer VIC 20 intended for private use is unrivaled."). The final rating of the prestigious Byte magazine is similar: "That the VIC is an astounding machine for the price is unquestioned." (German "It is undisputed that the VIC is an astonishingly good computer for its price."). But also magazines that are less specialized in computers, such as the science journal Popular Mechanics , end up with a positive overall rating:

“All in all, we think the VIC 20 is one of the most unusual and interesting of the lower priced computers. And for a price around $ 300, it's the only game in town that is more than just a game ”

“All in all, the VIC 20 is one of the most unusual and interesting among the cheap computers for us. And for a price of around $ 300, it is in a league of its own, although it is more than just a game. "

- Neil Shapiro, Popular Mechanics, Nov. 1981, p. 169.

These assessments were also confirmed in West Germany by the high-circulation magazine Chip and their choice of the VC 20 as the home computer of 1982. The following year, the widespread magazine Telematch, which specializes in video games, certified the VC 20 as performing well for its price class. Even if the full capacity of the "really cheap" device, according to the then widely read specialist author Dietmar Eirich, could only be accessed after expensive upgrades, especially of the main memory, the computer was definitely still recommended in 1984. The magazine HC-Heimcomputer sees a great advantage of the VC 20 in the fact that pupils can in many cases also use the software developed in school on the widely used school computers such as the PET and the CBM series on the VC 20 and vice versa.


In retrospect, the VIC 20 was perceived by the trade press as an extremely successful device and “million seller” shortly after its production was discontinued. Similar to the Sinclair ZX80 and ZX 81, its low price helped the computer to break through as a mass product. At the end of the 1990s, the non-fiction authors Jörg and Kerstin Allner attested the “little miracle calculator”, which was “little more than a keyboard with a built-in CPU”, a low price that “practically everyone could afford” and widespread use in West Germany. In addition, the computer is given the status of a “design legend” due to its characteristic housing shape - which its users "affectionately" refer to as a "bread box" or "neck roll" according to Allner.

Recent publications also speak of a cheap but low-performance entry-level device. The VC 20 "represented a cost-effective entry into the new, colorful world of home computers," writes Retro Gamer , a magazine that specializes in home computers and older video games . According to journalist Winnie Forster, the technology of the “unrivaled cheap” device was “already out of date at its debut” and according to the assessment of non-fiction authors Christian Zahn et al. "The VIC 20 ... compared to its big brothers in the 8000 series a step backwards". The US-American non-fiction authors Matt Barton and Bill Loguidice confirm with “Still, although the VIC 20 was a great value for the budget-conscious, its limitations were onerous for many enthusiasts” (German: “Nevertheless, although the VIC 20 the price-conscious much has offered, its limitations have made life difficult for many enthusiasts. ") and Steven L. Kent with" The VIC-20 was a pricing coup for its time ... the low end machine was a major success. " (German: "The VIC-20 was a prize coup for its time ... the low-end computer was a great success.") is the opinion of German authors. Brian Bagnall and Boris Kretzinger, on the other hand, see Commodore's pricing more differently: "The home computers were only apparently cheap ... because they weren't selling a full-fledged computer, but only a part ... of a whole computer system based on a modular system." And "This departure from the original all-in The one principle of PET was not criticized by the buyers ”.

The computer is often received in connection with the company history of its manufacturer and viewed as the basis for Commodore's triumphant advance in the home computer industry. From a German point of view, Zahn writes about the VC 20: "Although it was not the first successful home computer (that was the Sinclair ZX 81 due to its competitive price of DM 300), it was one that won many users for Commodore." The authors Matt Barton and Bill Loguidice are of the same opinion with “The VIC 20 was a smashing success, eventually selling millions of units and establishing Commodore's reputation for making highly capable computers at prices that rivaled the era's videogame consoles” (German: “Der VIC 20 was a resounding success with millions of units sold and established Commodore's reputation as a manufacturer of high-performance computers at the price of video consoles. ") And non-fiction author Roberto Dillon with" It was the first computer ever to sell more than one million units, catapulting Commodore into the arena of home entertainment while paving the way for all other 'home' machines to come, including the bestselling Commodore 64. ” (German: "It was the first computer from which more than a million pieces were sold. With it he catapulted Commodore into the home entertainment industry and at the same time paved the way for all other home computers, including the bestseller Commodore 64.").

Kretzinger goes one step further with his statement "VC-20 and C64 shape the home computer scene, not the expensive Apple II" and thus certifies the VC 20 a special role in home computer history. Retro Gamer magazine has a similar view:

"Even if the VC-20 was overshadowed by the Commodore 64: Retro fans shouldn't make the mistake of underestimating its role as an important (sic!) Pioneer of the 8-bit home computer."

- Retro gamer

The Commodore VIC 20 is a permanent exhibit in various computer museums, including the Berlin Computer Games Museum and the British National Museum of Computing .


Web links

Commons : Commodore VIC-20  - collection of pictures, videos and audio files
  • Sleeping Elephant - international forum for VIC-20 friends
  • VICE - emulator for different operating systems

Individual evidence

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This article was added to the list of excellent articles in this version on October 2, 2018 .