Commodore PET History Origins And The Early Models

Although it was no top seller outside the Canadian, US, and UK educational markets, it was Commodore's first full-featured computer and would form the basis for their future success.

1 History

1.1 Origins and the early models

In the 1970s Texas Instruments was the main supplier of CPUs for use in calculators. Many companies sold calculator designs based on their chip sets, including Commodore. However, in 1975 TI increased the price to the point where the chip set alone cost more than what TI sold their entire calculators for, and the industry they had built up was frozen out of the market.

Commodore responded by looking for a chip set of their own they could purchase outright, and quickly found MOS Technology, Inc. who were bringing their 6502 microprocessor design to market. Along with the company came Chuck Peddle's KIM-1 design, a small computer kit based on the 6502. At Commodore, Peddle convinced Jack Tramiel that calculators were a dead-end. Instead they should focus on making a "real" machine out of the KIM-1, and selling that for much higher profits.

The result was the first all-in-one home computer, the PET. The first model was the PET 2001, including either 4 KB (the 2001-4) or 8KB (2001-8) of RAM. It was essentially the KIM-1 with a new display chip (the MOS 6545) driving a small built-in monochrome monitor with 40x25 character graphics. The machine also included a built-in Datassette for data storage located on the front of the case, which left little room for the keyboard. The 2001 was announced in 1977For the album by Ash, see 1977 (album). Events January 1 First woman Episcopal priest ordained January 6 EMI sacks the Sex Pistols January 18 Scientists identify a previously unknown bacterium as the cause of the mysterious " legionnaire's disease" Januar and started deliveries around September. However they remained back-ordered for months, and to ease deliveries they eventually cancelled the 4K version early the next year.

Although the machine was fairly successful, almost everyone complained about the tiny keyboard. This was addressed in upgraded "dash N" and "dash B" versions of the 2001, which put the cassette outside the case, and included a much larger and better feeling keyboard. Internally a newer and simpler motherboard was used, along with an upgrade in memory to 8K, 16K or 32K, known as the 2001-N-8, 2001-N-16 or 2001-N-32, respectively.

Sales of the newer machines was strong, and Commodore then introduced the models to Europe. However there was already a machine called PET for sale in Europe from the huge Dutch PhilipsCompany logo Koninklijke Philips Electronics N. Royal Philips Electronics), usually known as Philips is one of the largest consumer electronics producers in the world. In 2003, their sales were €29. 0 billion and they employed 164,000 people in more company, and the name had to be changed. The result was the CBM 3000 series ('CBM' standing for Commodore Business Machines), which included the 3008, 3016 and 3032 models. Like the 2001-N-8, the 3008 was quickly dropped.

1.2 Education, business, and computer science

The final version of what could be thought of as the "classic" PET was the PET 4000 series. This was essentially the later model 2000 series, but with a larger black-and-green monitor and a newer version of Commodore's BASICCommodore BASIC is the dialect of BASIC used in Commodore International's 8-bit home computer line, stretching from the PET of 1977 to the C128 of 1985. The core part was based on 6502 Microsoft BASIC, licensed from the young Microsoft on a "pay once, no programming language. By this point Commodore had noticed that many customers were buying the "low memory" versions of the machines and installing their own RAM chips, so the 4008 and 4016 had the sockets punched out of the motherboard.

The 4032 was a huge success in schools, where its tough all-metal construction and all-in-one design made it better able to stand up to the rigors of classroom use. Just as important in this role was the otherwise underutilized IEEE 488 port the PET included. Used wisely, the port could be used as a simple "network" and allowed printers and disk drives (at this point in time, very expensive devices) to be shared among all of the machines in the classroom.

Two more machines were released in the PET series. The CBM 8000 included a new display chip which drove a 80x25 character screen, but this resulted in a number of software incompatibilities with programs designed for the 40 column screen, and it appears to have not been popular as a result.

The machine shipped with 32K standard as the 8032, but allowed another 64K to be added externally. Later the upgrade was installed from the factory, creating the 8096. Later models used an improved case with a separate keyboard and swivel mount for the monitor, known as the SK's and Execudesk.

The last in the series was the SP9000, known as the SuperPET or MicroMainframeThe designation Micromainframe (also rendered as MicroMainframe or Micro-mainframe may have at least two different meanings, depending on the context and originating company: The Commodore SP9000 SuperPET microcomputer The Intel iAPX 432 multiple-chip mic. This machine was designed at the University of WaterlooIn Detail) Motto: Concordia cum veritate ( Latin: In harmony with truth Chancellor Mike Lazaridis President David L. Johnston School type Public Religious affiliation Main campus: None Conrad Grebel: Mennonite Renison: Anglican St. Jerome's: Catholic St. for teaching programming. In addition to the basic CBM 8000 hardware, the 9000 added a second CPU in the form of the Motorola 6809The Motorola 6809 is an 8-bit microprocessor from Motorola, introduced circa 1979. The 6809 was a major advance over both its predecessors, the in-house Motorola 6800 and the latter's near clone the MOS Technology 6502. some would say 8/16-bit — see Descr and included a number of programming languages including BASIC in ROM for the 6502 and APL, COBOL, FORTRAN, Pascal and a 6809 assembler on floppies for the 6809. It also included a terminal program which allowed the machine to be used as a "smart terminal" as well, so this single machine could replace many of the boxes currently in use at the university. Additionally this machine became a remote development environment where the user could later upload their creation to a mainframe after completing development and testing on the SuperPET.

1.3 The graphics issue

As a home computer the line was quickly surpassed in sales by machines that included color graphics and sound, mainly the Apple II, Atari 8-bit family and TRS-80. In fact, it wasn't until an update fairly late in the history of the PET that the machine was even made capable of producing lower case letters. Although color was later solved in the Commodore VIC-20 and Commodore 64, the graphics issue could have been much less annoying if not for one problem -- the character set was "hard wired" in ROM, meaning it could not be changed. On other machines the location of the character graphics could be changed and pointed to RAM, where new characters could be drawn to create graphics. On the upside the PETs used a fairly good set of graphics characters (in their variation of ASCII, known as PETSCII) which allowed some rudimentary games to be created.

2 Model summary

2.1 PET 2001 series / 2001-N & -B series, CBM 3000 series

CPU: 6502, 1MHz

RAM: 4K, 8K, or 16K / 8K, 16K, or 32K

ROM: 18K, including BASIC 1.0 / 20K, including BASIC 2.0 (most CBM's with 3.0)

Video: MOS 6545, 9" monochrome monitor, 40×25 character display

Sound: none / single piezo "beeper"

Ports: MOS 6520 PIA, MOS 6522 VIA, 2 Datassette (1 used / 1 on the back), 1 IEEE-488

Notes: 69 key chiclet keyboard and built-in Datassette / full-sized, full-travel keyboard, no built-in Datassette

2.2 PET 4000 series / CBM 8000 series

CPU: MOS 6502, 1MHz

RAM: 8K, 16K or 32K / 32K or 96K

ROM: 20K, including BASIC 4.0

Video: MOS 6545, 9" or 12" / 12" monochrome monitor, 40×25 / 80×25 character display

Sound: single piezo "beeper"

Ports: MOS 6520 PIA, MOS 6522 VIA, 2 Datassette ports (1 on the back), 1 IEEE-488

Notes: basically an upgraded 2001 / basically a 4000 with 80 columns and slightly different keyboard with smaller (11 key) numeric pad

2.3 SuperPET 9000 series

CPU: MOS 6502 and Motorola 6809, 1MHz

RAM: 96K

ROM: 48K, including BASIC 4.0 and other programming languages

Video: MOS 6545, 12" monochrome monitor, 80×25 character display

Sound: single piezo "beeper"

Ports: MOS 6520 PIA, MOS 6522 VIA, MOS 6551 ACIA, 1 RS-232, 2 Datassette ports (1 on the back), 1 IEEE-488

Notes: basically an 8000 with ROMs for programming languages, it also had three character sets, and an RS-232 for use as a terminal

3 PET trivia

Seventeen years old at the time, British videogame designer-to-be Jeff Minter taught himself 6502 machine code on his school's PET 2001-8. At twenty, after dabbling with a UK ZX81, Minter founded his own company, Llamasoft (still in operation as of 2004), using his PET-obtained skills to develop games on his newly acquired VIC-20. He got his commercial breakthrough with the classic arcade shooter Gridrunner. Later Minter went on to write entertainment software for the C64 and Atari 400/800 as well as many non-6502 platforms such as the IBM PC, Atari Jaguar, and Nintendo Gamecube.

4 External links

Bo Zimmermann's pictures of CBM machines from his collection

List of Commodore microcomputers

Comm2 Comm2

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