A History of Commodore’s 8-bit Computers

Best known for the Commodore 64, the best selling single model in the history of computing, Commodore International was one of the first companies to enter the personal computing market and the first with a million-selling computer. Its first model was the Commodore PET.

Before the PET

Commodore got its start long before personal computers arrived. It was founded in Toronto, Ontario, Canada in 1954 as the Commodore Portable Typewriter Company by Polish immigrant Jack Tramiel. The company incorporated as Commodore Business Machines in 1955. In 1962, it was listed on the New York Stock Exchange as Commodore International.

When Japanese imports forced most North American typewriter manufacturers out of business in the late 1950s, Tramiel moved to adding machines. Then in the late 1960s, Japanese adding machines hit the North American market, once again threatening Commodore’s existence.

Tramiel went to Japan to figure out how to compete and came back with the idea of producing electronic calculators instead of mechanical adding machines. Once again, Commodore had a successful product on its hands – until in 1975 Texas Instruments (TI) entered the market with calculators that cost less than Commodore was paying for parts (TI was one of Commodore’s important suppliers).

Tramiel decided to head in another direction, took out a $3 million loan, and acquired chip manufacturer MOS Technology, Inc. to assure a steady supply of chips for his gear. Part of the agreement was that Chuck Peddle, MOS Tech’s chip designer, would join Commodore.

KIM-1 single-board computer

Commodore’s First Computer

Before home computers, there were hobbyist computers. The KIM-1 was one of the first, developed as a way for MOS Technology to demonstrate its 6502 CPU. The KIM-1 was the world’s first single-board computer when it was released in 1976. It had 1 KB of memory, a 6-digit LED display, a cassette interface, and 15 input/output ports. It sold for $245 and only required a power supply and some sort of enclosure for the 9″ x 10″ board.

This became the basis for many different projects and laid the foundation for Commodore’s first personal computer, which was released in 1977.

The Commodore PET

Peddle convinced Tramiel that calculators were a dead end, so Commodore should turn its attention to the fledgling personal computer market (often called home computers back then). Peddle designed a machine with a metal case, a keyboard, a built-in monitor, and a built-in cassette tape drive for loading and saving software and files. This was the Commodore PET 2001, which came to market in October 1977.

The PET was named in part for the pet rock fad, which lasted about six months during 1975. Silly as it sounds, 1.5 million pet rocks were sold during that period for $4.00 each, making their creator a millionaire. Officially, P.E.T. stood for Personal Electronic Transactor.

There were only two other home computers at that time: The Apple II, also built around the MOS 6502 CPU, had arrived in June 1977, replacing the Apple 1, which had been more of a do-it-yourself project. The Apple II sold for $1,298 with 4 KB of memory and could be used with a composite monitor or with a color or black-and-white TV (with an RF modulator) and cassette tape recorder, which many homes already had.

The other was the TRS-80 Model I, on sale at Radio Shack stores across the US since August 1977. It was based on the Zilog Z-80 CPU, and the 4 KB version retailed at $599, which included a screen and tape recorder.

The PET sold for $495 with the same 4 KB as its competitors. Commodore could only produce 30 units per day at that time, and orders came in so quickly that Tramiel decided to raise the price to $595. Next Commodore started pushing the 8 KB version at $795, since the 4 KB model left only 3 KB available for the user. In all, Commodore sold 500 PETs in 1977.

A Better BASIC

Commodore acquired a BASIC license from Microsoft, allowing it to install Commodore BASIC on as many machines as it could produce for a single, one-time fee. Over the years, it was installed on tens of millions of Commodore computers. Microsoft BASIC included floating point operations; the BASIC used in the TRS-80 and Apple II at that time only worked with integers.

The Datasette

The Datasette tape drive reads and writes data at 1500 bits per second, but the computer reads and writes data twice to verify integrity as well as using a parity bit. Unlike the cassette tape units used with other personal computers, the Datasette is a digital device, not analog.

It would take over 2 minutes to load an 8 KB program from tape, something developers addressed starting in 1980. The PET Rabbit for 16 KB and 32 KB PET and CBM computers used routines that made saving and loading data 4x as fast. At $30, it was a lot less expensive than a disk drive. (The January 1985 issue of Compute! magazine included TurboTape as a free type-it-in program for the Commodore 64 and a VIC-20 with at least 8 KB of memory expansion. TurboSaved programs did not require TurboTape to load. Like The PET Rabbit, it speeded up tape operations four-fold.)

The Display

The original PET has a 9″ display showing 25 lines of text with up to 40 characters per line (this uses just 1000 Bytes of memory). When Commodore introduced the PET 4000 series, it displayed the same amount of text on a 12″ screen, and the CBM 8000 family provides 80 columns of text, twice as much as earlier Commodores (also using twice as much system memory, 2000 Bytes).

The Keyboard and Character Set

One clever feature of the PET and later Commodore computers was the PETSCII character set, also known as CBM ASCII. In addition to the standard characters found on a keyboard, Commodore computers had a whole range of graphical symbols that could be accessed from the keyboard – and these characters were even printed on the keycaps for easy access.

The biggest complain about the original PET was its keyboard, which was laid out in a grid (see above keyboard layout) and not like a typewriter keyboard. Within a year Commodore introduced the PET 2001-N (right), which removed the tape drive and added a standard keyboard along with a numeric keypad (something the TRS-80 had but the Apple II did not).

In 1978, Commodore also expanded into Europe, where it sold its computers for twice as much as in the States – and it found ready buyers. European models were called CBM models, since Philips had a trademark on the PET name. The first models were the CBM 3008 (8 KB), 3016 (16 KB), and 3032 (32 KB).

Floppy Drives

In 1979, Commodore introduced its first floppy drive, the CBM 2040 dual drive with DOS 1.0 built into it. Like later Commodore floppy drives, it is an intelligent device with its own CPUs (two of them) and RAM that connected to the PET’s IEEE-422 parallel port. Each disk could store 170 KB of data on a single-sided 5-1/4″ floppy. Single drive mechanisms came later.

Because Commodore DOS was built into the floppy drive, you had to buy a new drive to get the latest version of DOS. The 2040 had DOS 1.0, the 4040 used 2.0 and later 2.1, the 8050 included DOS 2.5 and support for 500 KB high-density disks, and the 8250 had DOS 2.7 and could store 1 MB on a double-sided 5.25″ high-density floppy.

Improving PET

By 1980, the PET had moved from its original 9″ display to a 12″ screen, and along the way the metal case had been replaced by a plastic one. The European versions were the called the CBM 4016 and 4032.

Commodore also introduced the 8000 series, which featured 80 characters per row instead of 40 and was geared more toward business use.

VIC-20: The Wonder Computer of the 1980s

About three years after it announced the PET 2001, Commodore introduced the VIC-20, a low cost home computer.

PETs were monochrome computers, but Apple had been selling color computers since 1976. Commodore jumped on the color bandwagon with a new model designed for the home market and intended to be hooked up to your TV or a color monitor. The Commodore VIC-20 was a price breakthrough at US$299.99 when it was released in 1980.

It was first introduced in Japan in 1980, where it was called the VIC-1001 and included Japanese character support. It proved such a hit that some Japanese companies cancelled their plans for lower-cost computers. The VIC-20 became available in the rest of the world in 1981. Commodore sold 800,000 units in 1982 and was able to build up to 9,000 a day.

VIC stands for Video Interface Chip, the component that lets the VIC-20 display color. As for the 20, nobody knows for sure. The VIC-20 displays 22 characters of text per line and 23 lines of text (506 Bytes, just over half as much memory at the PET and 40-column CBM models used), and with a 16 KB memory cartridge it has a total 21 KB of RAM, but Michael Tomczyk, Commodore’s VIC Czar, says the number just sounded friendly.

The VIC-20 uses the same 1 MHz 6502 CPU found in the PET and Apple II, but it is equipped with far less memory than other 1980 machines – just 5 KB, of which 3.5 KB is available for programs. It uses the PETSCII character set, has 4 function keys on the right, works with any DE-9 Atari compatible joystick, and has a cartridge slot for games, programs, and memory expansion to a maximum of 40 KB (BASIC can only access 27.5 KB of memory).

Commodore pushed VIC-20 to the masses, including an ad campaign featuring William Shatner, Captain Kirk from Star Trek. And where PETs had been sold exclusively by computer dealers, VICs were sold in stores such as K-mart. The VIC-20 was the first computer to sell 1 million units.

Perhaps the most popular accessory was the Commodore 1530 C2N-B Datasette, which was much less expensive than a floppy drive – besides which the 1540 floppy drive, the model designed to work with the VIC-20’s disk drive port, wasn’t available until 1982.

Text adventures from Adventure International were put on cartridges and generated over $1.5 million in sales for Commodore.

Commodore developed the first modem to retail for under US$100 for the VIC-20, and the 300 bps VICModem became the first modem to sell 1 million units. A later version, the 15670, supports 1200 bps operation.

Commodore sold over 1 million VIC-20s, and in 1982 it was the best selling computer on the market. But it was about to be eclipsed by a more expensive upstart, and Commodore ended up dropping VIC’s price below $100 in April 1983. Production of the VIC-20 ended in 1984.

Commodore 64: The Upstart

Commodore 64

Rather than wait for the VIC-20 to peak before introducing its successor, Commodore chose to strike while the iron was hot and get the Commodore 64 to market as quickly as it could at the price point it wanted to reach. 64 KB of RAM cost over $100 in 1981, yet Commodore aimed at a US$595 retail price. Because Commodore owned MOS Technology and made most of its own chips, and because memory prices kept falling, it knew $595 was an attainable target.

Commodore 64 sales brochure In January 1982, the very year that the VIC-20 was the best selling personal computer, Commodore previewed the Commodore 64 (C-64) at the Consumer Electronics Show. It would go on to become the best selling single computer model of all time, as attested by Guinness World Records, although the exact number sold is unknown (at least 10 million and possibly as many as 17 million, although a figure of 12.7 million seems the most credible).

Where the VIC-20 had 5 KB of RAM, the C-64 had 64 KB. Where the VIC-20 had 23 lines of 22 characters, the C-64 had 24 lines of 40 characters. Commodore had a new version of the VIC chip, a new sound chip, and an enhanced version of the 6502 CPU known as the 6510 that let the computer access a full 64 KB of memory alongside 20 KB of ROM.

The VIC-1540 floppy drive had introduced for the VIC-20 in 1982. It includes DOS 2.6 and connects to the VIC-20 via a serial port. (Previous Commodore drives used the parallel port found in PETs and CBM models. The VIC-20 and its descendants do not have parallel ports.) Its 170 KB disk format is “mostly compatible” with earlier PET/CBM floppy drives.

The VIC-20 was the first personal computer to sell for under US$1,000 with a floppy drive.

The Commodore 64 was officially introduced in August 1982. Despite serious competition at home from Atari’s 8-bit computers and the Apple IIe, the $595 C-64 was the value champion at half the price of the Apple IIe with no need to add cards for floppy drives, printers, modems, and so on. (In the UK, the competition came from the BBC Micro and Sinclair ZX Spectrum.)

For VIC-20 owners, it was easy to move the Datasette and a printer to the C-64. The VIC-1540 floppy drive was not compatible with the C-64, so Commodore released the 1541 floppy drive for the C-64, which originally retailed at US$399.95. The 1541 also uses DOS 2.6.

The success of the VIC-20 and C-64 helped drive the Timex Sinclair 1000 and Texas Instruments 99/4A out of the market during the 1983 home computer price war. Commodore dropped the C-64 to $300 in June 1983, which TI countered by selling for TI 99/4A for $99 – losing money on every sale.

The Commodore 64 remained on the market until 1994, 12 years after its introduction. Commodore had hoped to keep the C-64 going for another year but ended up filing for bankruptcy in April 1994.

Commodore Bombs

Despite the success of the VIC-20 and C-64, Commodore made some poor moves while trying to grow its market.

Max – or Not

Commodore tried to sell a game console in 1982. It was called Max Machine in Japan, Ultimax in the US, and VC-10 in Germany. With just 2 KB of RAM, the same 6510 CPU as the C-64, and a target price of US$200, it couldn’t compete with the VIC-20 for value. It was discontinued within a few months due to dismal sales in Japan.

A C-64 to Go

In 1983, Commodore introduced the SX-64 executive computer, a portable C-64 along the lines of Osborne (5″ display, 24.5 lb.), Kaypro (9″ display, 29 lb.), Compaq (28 lb.), Zenith (Z-138 left, 24.2 lb., 2,600 cubic inches. I used one for a brief time while working at a Heath/Zenith store), and other luggable CRT-based portables larger than a big briefcase. The SX-64 has a built-in 1541 floppy drive (with storage space above the drive for a stack of floppies) and a 5″ CRT display. It sold for US$995 and was the first of these portables to include a color display.

The SX-64 weighed just 23 lb. (10.5 kg), and measured approximately 16.9″ x 14.6″ x 5.3″ (430 x 370 x 135 mm) – just over 1,300 cubic inches.

The SX-64 was a thing of beauty, as you can see by enlarging its image on the CBM Museum website (in German). We’ve reduced it significantly for use here. The attention to detail tells you Commodore really did intend the SX-64 as an executive machine.

The SX-64 did not sell well (estimated at about 85,000 units based on serial number data), even as Commodore discounted its retail price to move inventory. Commodore had announced a dual-drive DX-64, and a few of these appear to have reached the market, but it never went into full production because of low SX-64 sales – driven lower by people waiting for the DX-64.

Commodore 16

Trying to replace the entry-level VIC-20, Commodore introduced the Commodore 16 in 1984. It had just 16 KB of memory, used a 7501 or 8501 CPU, and was intended to compete with sub-$100 computers. By the time the C-16 shipped, Timex Sinclair, Mattel, and Texas Instruments had left the home computer market.

Visually, it was quite attractive with its dark grey case and VIC-20/C-64 styling.

But the C-16 had an inferior graphics chip vs. the C-64, had no modem port, could not connect to the existing Datasette, and had no game port, making it in many ways inferior to the VIC-20. Commodore did produce a C-16 compatible Datasette and joysticks for the C-16, but this model never caught on in the US market.

An even cheaper machine, the Commodore 116, was sold in Europe. Although functionally identical to the C-16, it had a smaller case and a rubber chiclet keyboard.

Commodore Plus/4

Released in June 1984, the Plus/4 was similar to the C-64 and also had four built-in applications, an office suite with a word processor, database, spreadsheet, and graphics program. It is more compatible with the C-16 than with the C-64 – however, that wasn’t a good thing. The C-64 was selling for US$199 when the Plus/4 came to market at US$299.

Although Commodore considered the Plus/4 its flagship model, it never sold well and was finally phased out in 1988.

Finally, Something Better

The Commodore 64 would not die. Commodore’s newer models were doing nothing to cut into its market. The C-64 was joined by the Commodore 128 in January 1985. The new model has two 64 KB banks of memory, supports 80-column text, includes an extended keyboard with a numeric keypad, and also contains a Zilog Z-80 CPU, enabling it to run CP/M software from the business world – although both processors cannot run at the same time.

The C-128’s primary CPU is an 8502 running at 2 MHz, twice the speed of the VIC-20 and C-64. The C-128 has three operating modes: native C-128 mode, CP/M mode, and 1 MHz C-64 mode that is nearly 100% compatible with the older machine’s software.

Commodore sold 4 million C-128s before it was discontinued in 1989. The C-64 remained on the market until 1994.

Commodore introduced two new floppy drives for the C-128, both running CBM DOS 3.0. The single-sided 1570 floppy drive uses the same 170 KB format as previous Commodore computers, can also read CP/M formatted floppies, and supports MS-DOS disks with additional software. The 1571 is a double-sided floppy drive with twice the storage. Commodore was unable to keep up with demand for the US$300 double-sided 1571.

Commodore 128D

Later in 1985, Commodore released the Commodore 128D, which follows the styling of the Amiga 1000 and DOS PCs with a separate keyboard. The 128D was the first 8-bit Commodore desktop computer with a built-in floppy drive – the 1571 mentioned above. It even had a handle on the left side to facilitate transporting the computer.

In late 1986, Commodore introduced a “cost reduced” version of the 128D in North America and parts of Europe. The 128DCR had a metal chassis in place of the plastic one in the original and eliminated the carrying handle.

C-64, the Next Generation

In 1986, Commodore introduced a refreshed version of the C-64 called the Commodore 64C. It is functionally identical to the earlier model but takes its styling cues from the Commodore 128.

Another Bomb

In 1990, Commodore repackaged the C-64 as a gaming console to compete with the Nintendo Entertainment Systems (NES) and the Sega Master System. Commodore went after the gaming market but never got any traction, as the C-64 was only a little more expensive and included a keyboard. The C64GS was another commercial failure for Commodore.

The Big Step Forward: Amiga

The future of 8-bit home computers was drawing to a close by the mid 1980s. The IBM PC had established the Intel 8088, a 16-bit CPU with an 8-bit data bus, as the business standard, and Apple introduced its Lisa business computer in 1983, followed by the first Macintosh in 1984. These were the first commercial computers with a graphical user interface and a mouse, something Microsoft quickly copied in developing Windows for the IBM PC and compatible clones.

Lisa and Macintosh used the Motorola 68000 CPU, a 32-bit chip with 24-bit addressing on a 16-bit data bus. Commodore chose the same CPU for its next computer family, the Amiga, which we cover in a separate article.

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