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EspañolCOMMODORE PET
The 'PET' ('''P'ersonal 'E'lectronic 'T'ransactor'') was a home-/personal computer produced by Commodore starting in the late 1970s.
Although it was not a 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.
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. Tramiel demanded that Peddle, and Tramiel's son, Leonard, create a computer in time for the upcoming trade show COMDEX (1976), and gave them six months to do it.
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 8 KB ('2001-8') of 8-bit RAM. It was essentially the KIM-1 with a new display chip (the MOS 6545) driving a small built-in monochrome monitor with 40×25 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 1977 and started deliveries around September. However they remained back-ordered for months, and to ease deliveries they eventually cancelled the 4 KiB version early the next year.
Although the machine was fairly successful, there were frequent complaints about the tiny keyboard, often referred to as a "chiclet keyboard" because the keys resembled the popular gum candy.
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 keyboard with a full stroke non-click motion.
Internally a newer and simpler motherboard was used, along with an upgrade in memory to 8, 16, or 32 KB, 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 Philips 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.
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 BASIC 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 PET's otherwise underutilized IEEE 488 port.
Used wisely, the port could be used as a simple "network" and allowed printers and disk drives (then very expensive) 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 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 KiB standard as the '8032', but allowed another 64 KiB to be added externally.
Later the upgrade was installed from the factory, creating the '8096'.
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 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.
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, due to demand, 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 KiB extension directly on the board and were sold as '8296' or, with a built-in 8250 dual disk drive, as '8296-D'.
In the home computer market the line was soon outsold by machines that included bitmapped color graphics and sound, mainly the Apple II (introduced in 1977, the same year as the PET 2001), Atari 400/800 (1979), and, in particular, Commodore's own bestselling VIC-20 (1980/81). The mainstream business computer market of the time considered colors and graphics somewhat less of an issue, a view that would change soon enough.
Bitmapping and colors aside, the main limitation of the PET's graphics capabilities was that the character set was "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 RAM, where new characters could be drawn by a programmer to create custom graphics shapes. From a programming point of view, this was a relatively simple method of producing good-looking graphics images, and because of this, as well as the acceptable speed obtainable by a BASIC program moving character objects on the screen compared to bitmap graphics, many programs with a certain amount of graphics, including a fair amount of games, were made this way even on bitmap-capable machines. The PET's lack of the character set remapping feature must therefore be said to constitute a major weakness in the machine's design.
On the upside, 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, allowing PET games with rudimentary graphics to be created, exemplified by clones of video games such as ''Space Invaders''. Also, the many popular text adventure games of the time, some multiplatform, some created for the PET line, did not need graphics at all. For specialized applications, alternative character sets could be programmed into an EPROM inserted in the character set ROM socket. Alternative character set EPROMs with diacritics and mathematical symbols were available in the aftermarket.
:CPU: 6502, 1 MHz
:RAM: 4 or 8 KB / 8, 16, or 32 KB
:ROM: 18 KB, including BASIC 1.0 / 20 KiB, including BASIC 2.0
:Video: discrete TTL video circuit, 9" monochrome monitor, 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, 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
:CPU: MOS 6502, 1 MHz
:RAM: 8, 16, or 32 KiB / 32 or 96 KiB
: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" (optional external speaker driven by MOS 6522 CB2 pin)
:Ports: 2 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
:CPU: MOS 6502 and Motorola 6809, 1 MHz
:RAM: 96 KB
:ROM: 48 KB, including BASIC 4.0 and other programming languages
:Video: MOS 6545, 12" monochrome monitor, 80×25 character display
:Sound: single piezo "beeper" (optional external speaker driven by MOS 6522 CB2 pin)
: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
Commodore Business Machines made a variety of disk drives available for the PET, using the IEEE 488 interface, including:
:Commodore 2031 single disk drive
:Commodore 4040 dual disk drive
:Commodore 8050 dual disk drive
:Commodore 8250 "quad density" dual disk drive
:Commodore 8280 dual disk drive (8")
:Commodore SFD-1001 "quad density" single disk drive
:Commodore 9060 hard drive (5 Megabytes)
:Commodore 9090 hard drive (7.5 Megabytes)
★ PET Transfer Protocol
★ Killer poke
★ Detailed discussion of PET 2001, with photos of exterior and interior
★ Bo Zimmermann's pictures of CBM machines from his collection
★ PET index
★ Commodore PET killer poke discussion
★ On the Edge: The Spectacular Rise and Fall of Commodore (2005) Variant Press, ISBN 0-9738649-0-7. — A book documenting the creation of the Commodore PET.
★ Commodore's version of the history
Although it was not a 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.
History
Origins and the early models
Design of the chiclet keyboard of the PET 2001 series
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. Tramiel demanded that Peddle, and Tramiel's son, Leonard, create a computer in time for the upcoming trade show COMDEX (1976), and gave them six months to do it.
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 8 KB ('2001-8') of 8-bit RAM. It was essentially the KIM-1 with a new display chip (the MOS 6545) driving a small built-in monochrome monitor with 40×25 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 1977 and started deliveries around September. However they remained back-ordered for months, and to ease deliveries they eventually cancelled the 4 KiB version early the next year.
Although the machine was fairly successful, there were frequent complaints about the tiny keyboard, often referred to as a "chiclet keyboard" because the keys resembled the popular gum candy.
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 keyboard with a full stroke non-click motion.
Internally a newer and simpler motherboard was used, along with an upgrade in memory to 8, 16, or 32 KB, 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 Philips 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.
CBM Model 4032
CBM 4040 dual disk drive (5.25")
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 BASIC 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 PET's otherwise underutilized IEEE 488 port.
Used wisely, the port could be used as a simple "network" and allowed printers and disk drives (then very expensive) 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 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 KiB standard as the '8032', but allowed another 64 KiB to be added externally.
Later the upgrade was installed from the factory, creating the '8096'.
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 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.
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, due to demand, 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 KiB extension directly on the board and were sold as '8296' or, with a built-in 8250 dual disk drive, as '8296-D'.
The graphics issue
In the home computer market the line was soon outsold by machines that included bitmapped color graphics and sound, mainly the Apple II (introduced in 1977, the same year as the PET 2001), Atari 400/800 (1979), and, in particular, Commodore's own bestselling VIC-20 (1980/81). The mainstream business computer market of the time considered colors and graphics somewhat less of an issue, a view that would change soon enough.
Bitmapping and colors aside, the main limitation of the PET's graphics capabilities was that the character set was "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 RAM, where new characters could be drawn by a programmer to create custom graphics shapes. From a programming point of view, this was a relatively simple method of producing good-looking graphics images, and because of this, as well as the acceptable speed obtainable by a BASIC program moving character objects on the screen compared to bitmap graphics, many programs with a certain amount of graphics, including a fair amount of games, were made this way even on bitmap-capable machines. The PET's lack of the character set remapping feature must therefore be said to constitute a major weakness in the machine's design.
On the upside, 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, allowing PET games with rudimentary graphics to be created, exemplified by clones of video games such as ''Space Invaders''. Also, the many popular text adventure games of the time, some multiplatform, some created for the PET line, did not need graphics at all. For specialized applications, alternative character sets could be programmed into an EPROM inserted in the character set ROM socket. Alternative character set EPROMs with diacritics and mathematical symbols were available in the aftermarket.
Model summary
PET 2001 series / 2001-N & -B series, CBM 3000 series
:CPU: 6502, 1 MHz
:RAM: 4 or 8 KB / 8, 16, or 32 KB
:ROM: 18 KB, including BASIC 1.0 / 20 KiB, including BASIC 2.0
:Video: discrete TTL video circuit, 9" monochrome monitor, 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, 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
PET 4000 series / CBM 8000 series
:CPU: MOS 6502, 1 MHz
:RAM: 8, 16, or 32 KiB / 32 or 96 KiB
: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" (optional external speaker driven by MOS 6522 CB2 pin)
:Ports: 2 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
SuperPET 9000 series
:CPU: MOS 6502 and Motorola 6809, 1 MHz
:RAM: 96 KB
:ROM: 48 KB, including BASIC 4.0 and other programming languages
:Video: MOS 6545, 12" monochrome monitor, 80×25 character display
:Sound: single piezo "beeper" (optional external speaker driven by MOS 6522 CB2 pin)
: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
Peripherals
Commodore Business Machines made a variety of disk drives available for the PET, using the IEEE 488 interface, including:
:Commodore 2031 single disk drive
:Commodore 4040 dual disk drive
:Commodore 8050 dual disk drive
:Commodore 8250 "quad density" dual disk drive
:Commodore 8280 dual disk drive (8")
:Commodore SFD-1001 "quad density" single disk drive
:Commodore 9060 hard drive (5 Megabytes)
:Commodore 9090 hard drive (7.5 Megabytes)
See also
★ PET Transfer Protocol
★ Killer poke
External links
★ Detailed discussion of PET 2001, with photos of exterior and interior
★ Bo Zimmermann's pictures of CBM machines from his collection
★ PET index
★ Commodore PET killer poke discussion
★ On the Edge: The Spectacular Rise and Fall of Commodore (2005) Variant Press, ISBN 0-9738649-0-7. — A book documenting the creation of the Commodore PET.
★ Commodore's version of the history
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