The COMMODORE PET (PERSONAL ELECTRONIC TRANSACTOR) is a line of home
/personal computers produced starting in 1977 by Commodore
International . A top-seller in the Canadian and United States
educational markets, it was Commodore's first full-featured computer,
and formed the basis for their entire
8-bit product line, including
* 1 History
* 1.1 Origins and the early models * 1.2 Education, business, and computer science * 1.3 Graphics display
* 2 Model summary
* 2.1 PET 2001 series / 2001-N "> The chiclet keyboard of the PET 2001 series The integrated Datasette reader PET 2001 with its top lifted
In the 1970s Commodore was one of many electronics companies selling
calculators designed around
Commodore responded to this by searching for a chip set they could
purchase outright. They quickly found
The PET 2001 was announced at the Winter CES in January 1977 and the first 100 units were shipped later that year in October. However, the PET was back-ordered for months and to ease deliveries, early in 1978 Commodore decided to cancel the 4 kB version (also because the user would be left with barely 3 kB of RAM).
Commodore was the first company to license Microsoft's 6502 BASIC, but the license agreement nearly drove Microsoft into receivership as Commodore stipulated that they would only pay for the BASIC license after the PET began shipping. However, this took over six months to finally happen, during which time Microsoft lost money and even worse, had their cash reserves further depleted by a lawsuit over ownership of Altair BASIC. At the end of the year, the struggling company was saved by Apple's decision to license Microsoft BASIC for the Apple II line.
Although the machine was moderately successful, there were frequent
complaints about the tiny calculator-like keyboard, often referred to
as a "chiclet keyboard " because the keys resembled the chewing gum it
was named after. The key tops also tended to rub off easily.
Reliability was fairly poor, although that was not atypical of many
early microcomputers. Because of the poor keyboard on the PET,
external replacement ones quickly appeared. The PET had somewhat of a
competitive advantage over its
In 1979, Commodore replaced the original PET 2001 with an improved
model known as the 2001-N (the N was short for "New"). The new machine
used a standard green-phosphor monitor in place of the light blue in
the original 2001. It now had a conventional, full-sized keyboard and
no longer sported the built-in cassette recorder. The kernel ROM was
upgraded to add support for Commodore's newly introduced disk drive
line. It was offered in 8kB, 16kB, or 32kB models as the 2001-N8,
2001-N16, and 2001-N32 (the 8kB models were dropped soon after
introduction). The 2001-N switched to using conventional D
Sales of the newer machines were strong, and Commodore then introduced the models to Europe. 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. The change to CBM occurred because of a trademark dispute with Philips over the PET name.
EDUCATION, BUSINESS, AND COMPUTER SCIENCE
CBM Model 4016 CBM Model 4032 CBM 4040 dual disk drive (5.25") CBM 8296-D with 2 floppy disk drives
In 1980, the 4000-series PETs were launched. These used a larger 12"
monitor with a redesigned CRT controller and also included the
enhanced BASIC 4.0, which added commands for disk functions. By this
point, Commodore discovered that people were buying cheaper 8 kB and
16 kB models of the 3000-series and upgrading the
The PET's simple, rugged design and completely enclosed components made it an early favorite in the North American education market. At one point Commodore owned 67% of the Canadian education market. Schools preferred the 40-column models because the 40-column display's larger characters vs. the 80xx PETs were easier for young children to read. Commodore manufactured a variation on the PET called "Teacher's PET" - these were relabeled 2001-series PETs which were donated by Commodore as part of a "buy 2 get 1 free" program offered to schools as part of a promotion/tax write-off scheme.
Two more machines were released in the PET series. The 8000 series included a new display chip which drove an 80×25 character screen, but this resulted in a number of software incompatibilities with programs designed for the 40 column screen, and it appears to have been unpopular as a result. The machine shipped with 32 kB standard as the 8032, but allowed another 64 kB to be added externally. Later the upgrade was installed from the factory, creating the 8096. Unlike the 40-column models, 8000-series PETs came standard with a 1-channel speaker for sound generation.
2001/3000 and 4000-series PETs used what became known as the "graphics keyboard". Numbers were exclusively on the numeric keypad and the row above the alphabet keys had only punctuation symbols. The 3032 and 4032 were produced in two special variants known as the B models with the so-called "business keyboard", which had a conventional layout with mathematical symbols and numbers above the alphabet keys. The keypad contained only numerals. On the other hand, all 8000-series PETs sported the business layout.
The 4000/8000 PETs were more explicitly targeted at
professional/business use than the 2001/3000. Business customers were
the main target for the features of the enhanced BASIC 4.0, and a good
selection of prepackaged business software was available. A large
line of 5.25" and 8" floppy drives were made for the PET family, and
even 5 and 7MB external hard disks . While they became fairly popular
for business use in Europe, they failed to make much impact on the US
market in part because the 6502-based PETs could not run
As noted above, 4000 and 8000-series PETs used larger monitors and a
different video controller than the 2001/3000 models. This created a
notorious compatibility problem known as the killer poke . On
2001/3000 PETs, there was a register which when enabled did not allow
reading/writing of the video
The PET 2001 and 2001-8N had a register that would disable the video
output; this was also used as output for the
The last in the series was the SP9000, known as the SuperPET or
MicroMainframe. This machine was designed at the University of
Waterloo for teaching programming. In addition to the basic CBM 8000
hardware, the 9000 added a second CPU in the form of the Motorola 6809
Commodore tried to update the PET line with a new redesign called the CBM-II series (also known as the B series). These were not as successful and were ultimately abandoned. However, because the PET remained popular in Europe, the original PET machines were revived and the CBM-II case style was retained. These were known as the SK's (due to the separated keyboard). They also had a swivel monitor. Originally, standard 8032 boards were retrofitted into these cases. Later the SK models got a new mainboard that already included the 64 kB extension directly on the board and were sold as 8296 or, with a built-in 8250 dual disk drive, as 8296-D. The revived PET line also included a new pair of floppy drives, the SFD-1001 and 2031 (see below for more info).
Although not officially a member of the PET series, in 1983 Commodore
packaged C64 motherboards in plastic cases similar to the PET
4000-series in order to create the
Educator 64 . This was an attempt
to retake some of the education market they had largely lost by then
Play media Dutch newsreel from 1979 in which a PET is shown
In the home computer market the PET line was soon outsold by machines
that supported high-resolution color graphics and sound, mainly the
Without the High Resolution Graphic board, the PET's graphics
capabilities were limited to a character set hardwired in ROM . On
many of the PET range's home computer rivals, the look-up address of
the character graphics could be changed and pointed to
Somewhat offsetting this drawback, the PET's ROM-restricted character
set — an ASCII-1963 deviation known as
PETSCII — was one of the
most varied and flexible of the era. It allowed PET games with
rudimentary graphics to be created, exemplified by clones of video
games such as
Other than a PC speaker -class beeper, PETs did not have sound hardware (except for the 8000 models), but it was possible to rig a circuit up to the 6522 "user" port that could be used to output square wave tones to an external amplifier, and some games supported this feature.
The PET had two empty sockets on the motherboard for adding expansion ROMs, which could be a total of 8k in size. A predecessor to the cartridge slots on later Commodore machines, they allowed various software add-ons such as machine language monitors. In addition, it was common for commercial programs to include a copy protection ROM that had to be installed prior to running the application; something of an inconvenience to users owning multiple applications protected in this way, as the chips would have to be swapped in order to run their respective programs.
PET 2001 SERIES / 2001-N "> CPU: 6502 , 1 MHz RAM: 4 or 8 kB /
8, 16, or 32 kB ROM: 18 kB, including BASIC 1.0 / 20 kB, including
BASIC 2.0 (disk drives not supported on the original 2001) Video:
discrete TTL video circuit, 9" monochrome monitor (blue phosphor on
the original 2001, green on 2001-N PETs), 40×25 character display
Sound: none / single piezo "beeper" (optional external speaker driven
by MOS 6522 CB2 pin) Ports: 2 MOS 6520 PIA, MOS 6522 VIA, 2x
Datassette (1 used / 1 on the back), 1x
PET 4000 SERIES / CBM 8000 SERIES
CPU: MOS 6502, 1 MHz RAM: 8, 16, or 32 kB / 32 or 96 kB ROM: 20 kB,
including BASIC 4.0 Video: MOS 6545 12" / 12" monochrome monitor,
40×25 / 80×25 character display Sound: single piezo "beeper" Ports:
2 MOS 6520 PIA, MOS 6522 VIA, 2
Datassette ports (1 on the back), 1x
SUPERPET 9000 SERIES
SuperPET SP9000 CPU: MOS 6502 and
Commodore Business Machines made a variety of disk drives available
for the PET, using the
The original lineup of disk drives for the PET were the dual-unit 2040, 3040, 4040, 8050, and 8250. Later (near the end of the PET's lifespan), single-unit 2031 and SFD-1001 drives were produced that used the same case as the 1540/1541, but sported the PET's parallel interface instead of the VIC-20/C64 IEC interface. The 4040/2031 used the same 170 kB format as the 1541 and is completely read/write compatible (although software that performs low-level drive access will not work). 8050 and 8250 drives had an incompatible 500 kB/1 MB format, but were popular well into the 1980s as server/BBS storage devices because of their large capacity.
In addition, Commodore had 8" 8060, 8061, 8062, and 8280 drives which used MFM encoding instead of the GCR used on their other disk drives and was mainly intended to allow PET users to read disks written on IBM mainframes/minicomputers. 5 MB and 7.5 MB hard disks were produced as well. They have no directory support and are treated by the kernel ROM as simply a larger floppy disk.
All PET peripherals will work on VIC-20/C64/Plus-4/C128 machines with a parallel → IEC adapter (reverse IEC → parallel adapters were also made), and as mentioned above, 8050/8250 drives were sometimes used on C64s for BBS service because of their large capacity and faster interface.
An alternative option for adding floppy disk capability to the PET
was the Computhink disk system. Although references to this system
are hard to find today, it was nevertheless popular at the time, as it
was both cheaper and considerably faster than the Commodore system and
available from an earlier date. Unlike the Commodore units, it did not
* PETSCII * PET Transfer Protocol
* ^ A B What's New (February 1978), "Commodore Ships First PET Computers", BYTE, Byte Publications, 3 (2): 190 Commodore press release. "The PET computer made its debut recently as the first 100 units were shipped to waiting customers in mid-October 1977." * ^ A B Matthews, Ian (February 22, 2003). "The Amazing Commodore PET". commodore.ca. * ^ Bagnali, Brian, Commodore- A company on the edge, 2011. * ^ Walter Isaacson, Steve Jobs, 2011. * ^ Bagnall, Brian (2006), On The Edge — The Spectacular Rise and Fall of Commodore, Winnipeg, Manitoba: Variant Press, p. 53, ISBN 0-9738649-0-7 * ^ Anon 1978 , p. 1 * ^ "The Commodore PET". * ^ * ^ Anon 1978 , pp. 57–64 * ^ Bellis, Mary, The First Hobby and Home Computers: Apple I, Apple II, Commodore PET, and TRS-80, about.com * ^ "A tribute to Jack Tramiel, father of Commodore 64". * ^ Forster, Winnie (2005), The encyclopedia of consoles, handhelds & home computers 1972 - 2005, GAMEPLAN, p. 23, ISBN 3-00-015359-4 * ^ "RUN Magazine Issue 30". * ^ "PET/CBM FAQ - MODELS OF THE PET/CBM". * ^ Commodore Microcomputers Issue 31 * ^ * ^ "PET-Grafikkarte Commodore ASSY No. 324402-01 für CBM 8296". CBMPET.DE. * ^ "Compute - The Journal of Progressive Computing - 002" (pdf). January–February 1980. p.