Commodore PET
Model:PET 2001
Introduced:January 1977
Released:June 1977
Price:US $795
CPU:MOS 6502, 1MHz
RAM:4K, later 8K
Display:40 X 25 text
built-in 9" screen
Ports:IEEE-488, cassette
parallel, system bus
Storage:Built-in cassette
OS:BASIC in ROM

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This is the first Commodore computer, the PET, or the Personal Electronic Transactor. It appears that they just made up that description, though, as the name "PET" was apparently chosen to capitalize on the pet rock fad going on at the time.

Some PETs have a black screen-trim, some are blue. The black-trim PET seen above has a simple adhesive sticker applied for the large label seen below the screen, but the blue-trim system has a nice painted metal plaque.

Where did the PET come from?
There was an earlier Commodore computer, the KIM-1, but Commodore didn't design it, they inherited it when they bought MOS Technologies, who designed and produced computer chips - the KIM-1 was a way to demonstrate the power of the MOS 6502 CPU to the industrial community.

Chuck Peddle was an engineer at MOS who worked on their 6502 CPU, as well as the KIM-1 computer. When Commodore wanted a reliable source of chips for their computers, they bought MOS, renamed it as the Commodore Semiconductor Group, and Chuck Peddle became a full-time Commodore employee.

His first order of business - convince Commodore that calculators were "out", computers were "in". It worked - Chuck Peddle went on to design the PET, one of the very first user-friendly computers. It was designed around the MOS Technologies 6502 CPU, which eventually came to be used in many of the popular computers of the day - the Apple II, Atari 400/800, AIM-65, and others.

The PET has a built-in display, although it looks like a monitor perched on top. It is part of the machine and does not come off. Very stylish and user-friendly.

This is one of the few computers with a built-in cassette drive - very handy, but the keyboard is one of the worst! The keys are of a type known as 'chiclet', tiny and difficult to type on. Touch-typing is impossible.



The PET has four external expansion ports. A parallel port, a cassette recorder port, the system bus, and an IEEE-488 port. The IEEE-488 is relatively complex, allowing up to 15 devices on the bus. Commodore released a giant dual-drive floppy-disk unit which plugged into the IEEE-488 port. You can see it on the PET 4032 page.

That built-in cassette drive is very convenient, but its origins are less than impressive - it's merely a modified generic external cassette tape recorder bolted to the underside of the PET body. Saving money is the name of the game!

Early on, PET users figured-out a way to make the screen update faster, hence the entire system would run faster. This was accomplished by typing in the "POKE 59458,62" command sequence from the keyboard.

To test this theory, I ran this short BASIC program on my PET 2001-8:

10 FOR X=1 TO 1000
20 PRINT X;
30 NEXT X

  • It took 19 seconds to finish in 'normal' mode.
  • It took 13 seconds to finish after I entered the POKE sequence listed above.
    • It works! The only obvious side-effect seems to be random 'twinkling' on the screen.

    [Technical explanation: The PET will not update the video memory (static RAM) while painting the display, only in between screens. You can trick the system by switching bit 5 of the 6522 VIA I/O Register B from "input mode" to "output mode" - now the system no longer waits for the video sync signal, thinking that it's always present, and updates the screen as fast as it can. There is a penalty for this, though, as the display will now show random speckles throughout.]

    Unfortunately, on later versions of the PET, this POKE command sequence will NOT make the system run faster, instead it distorts the screen and can eventually damage the circuit.
    This became known as the "Killer Poke", because it might kill your computer.







    The requisite PET 2001 "open hood" photo - the top of the PET, normally screwed down, opens for maintenance like the hood of your car.

    There's really not much the owner can do inside of the PET, except increase the RAM from 4K to 8K, if this has not already been done.

    The entire body of the PET - the base, the upper section, and the monitor, are all made of sheet metal.

    Here you can also see the cassette drive held in-place by brackets and bolts.



    This nice 'blue' PET has some especially old ROM chips installed - white ceramic! With just a hint of rust...

    Most IC chips seen are encased in black plastic - cheaper and more durable. Both of these ceramic chips are cracked.


    Want composite video from your PET-2001? Try this circuit from the Commodore Pet Users Club of England!
    (Correction: 2200mf = 2200pf)

    The PET was quite popular in schools due to its simple use and all-in-one design - Commodore released numerous PET systems, each slightly different than the other, but the original 2001 series is the only one with the internal cassette drive and the tiny keyboard.
  • PET 3032
  • PET 4032
  • CBM 4016
  • CBM 8032
  • CBM 8296

    Easter-egg? - In an early PET Microsoft Basic, type the command WAIT 6502. The screen will fill with the text "MICROSOFT". This apparently was inserted by Bill Gates himself in order to assert Microsoft's copyright on PET BASIC after he had had an argument with Commodore founder Jack Tramiel. This does NOT work on my PET 2001-8 system, it requires the newer version of BASIC available on the 'full-size keyboard' models.

    Related Links

  • Inside the Commodore PET
  • Here are schematic diagrams of different Commodore computers
  • Welcome to the Commodore 8-bit server
  • Dan's 8-bit Commodore Info
  • The Secret Weapons of Commodore
  • The Commodore Billboard
  • 6502.org




    • History of Commodore Computers

    • 1953: Jack Tramiel opens a typewriter repair shop in the Bronx, New York.
    • 1954: Tramiel founds Commodore.
    • 1955: Tramiel relocates to Toronto and becames the biggest manufacturer of low cost office furniture in Canada
    • 197? Commodore manufactures calculators and digital watches, but gets killed by Texas Instruments.
    • 1976: Commodore purchases MOS Technologies, an American maker of IC chips. MOS' senior engineer, Chuck Peddle was working on the 6502 micro processor. A popular 8 bit processor that soon would be used in machines like the Apple II, the Atari 800, the Commodore PET and 64.
    • 1977: January - Commodore first shows a prototype PET computer at the Winter Consumer Electronics Show.
    • 1977: January - Commodore's Chuck Peddle shows the first PET to Radio Shack, hoping to have Radio Shack sell it.
    • 1977: April - Commodore Business Machines Inc. shows its PET 2001 computer for US$600. The computer shown is a one-of prototype.
    • 1977: June - Commodore shows its first production PET computers at the Summer Consumer Electronics Show.
    • 1980: May - Commodore Business Machines introduces the CBM 8032 microcomputer, with 32KB RAM and an 80-column monochrome display.
    • 1980: May - Commodore Business Machines introduces the CBM 8050 dual 5 1/4-inch floppy disk drive unit.
    • 1980: Commodore Japan introduces the VIC-1001 (later called the VIC-20 in the USA).
    • 1981: January - Commodore announces the VIC-20, for US$299. During its life, production peaks at 9,000 units per day.
    • 1982: Hi-Toro Incorporated is formed by a group of midwest investors trying to cash in on the video game craze. The name was later changed to Amiga, Incorporated after being confused with the lawn-mower manufacturer, Toro. Within one year, there are rumours of an incredible computer codenamed Lorraine featuring unheard of graphics and sound capabilities, multitasking, 80 column display, 5+ megs of Ram and MORE!
    • 1982: January - Commodore announces the Commodore 64 microcomputer, showing a prototype at the Winter CES, for US$600) for US$595.
    • 1982: January - Commodore introduces the 16K SuperVIC.
    • 1982: April - Commodore announces the B (700) and P (500) series of microcomputers, for US$1700-3000.
    • 1982: June - Commodore Business Machines introduces the BX256 16-bit multiprocessor professional microcomputer, for US$3000.
    • 1982: June - Commodore Business Machines introduces the B128 microcomputer, for US$1700.
    • 1982: June - Commodore Business Machines announces the P128 microcomputer. It is to be an enhanced Commodore 64 with 128KB RAM expandable to 896KB. Price US$995.
    • 1982: September - Commodore Business Machines begins shipping the Commodore 64. Suggested retail price is US$595.
    • 1982: Commodore releases the 1540 Single-Drive Floppy for the VIC-20.
    • 1983: January - Commodore Business Machines begins selling the Commodore 64 through mass merchants, which drops the retail price to US$400.
    • 1983: January - At the Winter CES, Commodore debuts the Commodore SX-100, a portable version of the Commodore 64, with bundled B/W screen, for US$995. Price with color screen and two drives is US$1295.
    • 1983: January - At the Winter CES, Commodore demonstrates the HHC-4 (Hand-Held Computer). It features 24-character LCD screen with 4 KB RAM expandable to 16 KB. This was one of Commodore's pre-PET business products. Price is US$199.
    • 1983: January - Commodore's sales of VIC-20s reaches 1,000,000.
    • 1983: January - Commodore introduces the SX-64, the first color portable computer. Weight is 10.5 kg. It incorporates a 5-inch color monitor and one or two 5.25 inch floppy drive. Price is US$1600.
    • 1983: April - Commodore drops dealer prices on the VIC-20, which allows it to drop below US$100 retail, the first color computer to hit that mark.
    • 1983: April - Commodore offers a US$100 rebate on the purchase of a Commodore 64 on receipt of any computer or videogame unit.
    • 1983: May - Commodore ships the Commodore Executive 64. It features 64KB RAM, detachable keyboard, 5-inch color monitor, 170KB floppy drive, for US$1000.
    • 1983: June - Commodore drops the dealer price of the Commodore 64 to US$200, allowing the retail price to drop to US$200-230.
    • 1983: June - At the Summer CES, Commodore shows the B128/256-80, formerly called P128. It has a monochrome monitor with 80-column display. They also show the Executive 64, formerly the Commodore SX-100. It has a 6-inch color monitor and is priced at US$995.
    • 1983: Commodore debuts the Exactron Stringy Floppy, a high-speed cassette-based data storage device.
    • 1984: January - Jack Tramiel,President of Commodore International, has a disagreement with the major share holder, Irvin Gould. Tramiel leaves the company and a few months later buys Atari.
    • 1984: January - At the Winter CES, Commodore shows the SX-64, formerly called Executive 64. It now includes a 5-inch monitor, and one 170KB 5 1/4 disk drive, for US$995.
    • 1984: January - Commodore announces that during 1983, Commodore sold US$1 billion worth of computers, the first personal computer company to do so.
    • 1984: June - Commodore announces the Commodore 16. Former name was TED-16 and is expected to sell for around US$100, and marketed as "The Learning Machine".
    • 1984: June - Commodore announces the Commodore Plus/4, formerly called the Commodore 264. It will now feature four built-in programs, not just one. Price should be around US$300.
    • 1984: August - Commodore purchases Amiga Corporation.
    • 1984: Commodore stops manufacturing the VIC-20.
    • 1985: January - Commodore unveils the Commodore 128 Personal Computer. It functions as three computers in one: a complete Commodore 64, a CP/M mode, and a new 128KB mode.
    • 1985: January - Commodore announces the 1571 Disk Drive, for the Commodore 128.
    • 1985: July - Commodore unveils the new Amiga 1000 in New York, for US$1300.
    • 1985: Commodore stops production of the Commodore 64 several times during the year, restarting each time based on public demand.
    • 1986: Commodore releases Transformer software for the Amiga, which, along with the Commodore 1020 5 1/4-inch disk drive, provides limited MS-DOS compatibility.
    • 1987: January - Commodore announces the Amiga 500 and the Amiga 2000.
    • 1987: January - Commodore debuts the Commodore 128D in the North American market.
    • 1988: December - Commodore announces the A2286D Bridgeboard for the Amiga 2000. The A2286D contains an 8-MHz Intel 80286 and a 1.2MB 5 1/4-inch disk drive.
    • 1988: Commodore introduces the Amiga 2000HD and the Amiga 2500.
    • 1989: January - Commodore announces that 1 million Amiga computers have been sold.
    • 1989: November - Commodore announces the Amiga 2500/30. It is essentially an Amiga 2000 with a 2630 Accelerator Board (25-MHz 68030 and 68882 math coprocessor).
    • 1990: April - Commodore offers Amiga 1000 owners US$1000 to trade in their Amiga on a new Amiga 2000.
    • 1990: June - Commodore ships the Amiga A3000 computer.
    • 1990: September - NewTek ships the Video Toaster, a hardware/software video effects tool for the Commodore Amiga 2000, for US$1600.
    • 1990: Commodore announces the Amiga 3000. Prices start at US$4100 with a monitor.
    • 1991: January - Commodore releases the CDTV package. It features a CD-ROM player integrated with a 7.16-MHz 68000-based Amiga 500. List price is US$1000.
    • 1992: Commodore introduces the Amiga 600 for a base price of $500.
    • 1992: September - Commodore introduces the Amiga 4000.
    • 1992: December - Commodore introduces the Amiga 1200.
    • 1994: Commodore International and Commodore Electronics (two of the many international components of Commodore Business Machines) file for voluntary liquidation.
    • 1995: April - At an auction in New York, ESCOM buys all rights, properties, and technologies of Commodore.
    • 1997: Gateway buys bankrupt Amiga.
      Source: Chronology of Events in the History of Microcomputers



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