Editing Commodore PET (section)

===Release===
[[File:PET 2001 Series-IMG 1724.JPG|thumb|The [[chiclet keyboard]] of the PET 2001 series]]
[[File:PET_Keyboard_improved.svg|thumb|Drawing of [[chiclet keyboard]] of the PET 2001 series]]
[[File:Commodore pet 2001 internal cassette recorder.jpg|thumb|An early PET 2001 integrated cassette recorder]]
[[File:Commodore PET 2001 with lifted top.jpg|thumb|upright|PET 2001 with its top lifted]]

The Commodore PET was officially announced in 1976 and Jack Tramiel gave Chuck Peddle six months to have the computer ready for the January 1977 [[Consumer Electronics Show]], with his team including John Feagans, Bill Seiler, two Japanese engineers named Fujiyama and Aoji, and Jack's son Leonard Tramiel,{{Sfn|Tomczyk|1984|pp=30–32}} who helped design the [[PETSCII]] graphic characters and acted as quality control.

The result was Commodore's first mass-market personal computer, the PET, the first model of which was the PET 2001. Its 6502 processor controlled the screen, keyboard, cassette tape recorders and any peripherals connected to one of the computer's several expansion ports.<ref>{{Harvnb|Anon|1978|p=1}}</ref>

The PET 2001 included either {{nowrap|4 KB}} (2001-4) or {{nowrap|8 KB}} (2001-8) of 8-bit [[random-access memory|RAM]], and was essentially a [[single-board computer]] with discrete logic driving a small built-in [[monochrome monitor]] with {{nowrap|40×25}} character graphics, enclosed in a [[sheet metal]] case that reflected Commodore's background as a manufacturer of [[office equipment]].<ref>{{cite web|url=http://www.portcommodore.com/dokuwiki/doku.php?id=larry:comp:commodore:pet:start|title=The Commodore PET}}</ref>

The machine also included a built-in [[Commodore Datasette|Datasette]] for data storage located on the front of the case, which left little room for the keyboard. The data transfer rate to cassette tape was 1500 [[baud]], but the data was recorded to tape twice for safety, giving an effective rate of 750 baud.<ref>[http://www.atarimagazines.com/compute/issue57/turbotape.html How TurboTape Works], By Harrie De Ceukelaire (With Ottls Cowper, Technical Editor, And Charles Brannon, Program Editor), COMPUTE! ISSUE 57 / FEBRUARY 1985 / PAGE 112</ref>

The computer's main board carried four expansion ports: extra memory, a second cassette tape recorder interface, a parallel ("user") port which could be used for sound output or connection to "user" projects or non-Commodore devices and a parallel [[IEEE-488]] port which allowed for [[Daisy chain (electrical engineering)|daisy-chaining]] peripherals such as disk drives and printers.<ref>{{Harvnb|Anon|1978|pp=57–64}}</ref>

A working PET 2001 prototype was shown to the public at the Winter CES 1977 in January 1977,{{Sfn|Tomczyk|1984|p=32}} and the first hundred units were shipped in October, mostly going to magazines and software developers, while the machine was not generally available to consumers until December.<ref name = "Byte Feb 1978">{{Citation | author = What's New |date=February 1978 | title = Commodore Ships First PET Computers | journal = BYTE | volume = 3 | issue = 2 | page = 190 | publisher = Byte Publications}}Commodore press release. "The PET computer made its debut recently as the first 100 units were shipped to waiting customers in mid-October 1977."</ref> However, the PET was back-ordered for months, so to ease deliveries, early in 1978, Commodore decided to cancel the 4&nbsp;KB version (also because the user would be left with barely {{nowrap|3 KB}} of RAM).<ref>{{cite web |title=A tribute to Jack Tramiel, father of Commodore 64|website=[[ZDNet]]|url=http://www.zdnet.com/pictures/a-tribute-to-jack-tramiel-father-of-commodore-64-gallery/4/|archive-url=https://web.archive.org/web/20150207205228/http://www.zdnet.com/pictures/a-tribute-to-jack-tramiel-father-of-commodore-64-gallery/4/|url-status=dead|archive-date=February 7, 2015}}</ref>

Commodore was the first company to license [[Microsoft]]'s 6502 BASIC, but the agreement nearly drove Microsoft into [[receivership]] as Commodore stipulated that they would only pay for it when the PET began shipping.

This was delayed by over six months, during which Microsoft lost money and had their cash reserves further depleted by a lawsuit over ownership of Altair BASIC. At the end of the year, Microsoft was saved by Apple's decision to license Microsoft BASIC for the Apple II line.

The BASIC included on the original PET 2001 was known as Commodore BASIC 1.0; Microsoft supplied Commodore with a [[source code|source listing]] for their 6502 BASIC, essentially a [[Porting|port]] of BASIC-80, and Commodore performed the rest of the work themselves, including changing the startup screen and prompts, adding [[Input/output|I/O]] support, the [[SYS (command)|SYS]] command for invoking [[Machine code|machine language]] programs, and fixing [[Bug (engineering)|bugs]]. BASIC 1.0 still had numerous bugs and IEEE-488 support was broken, so that when Commodore later came out with disk drives, they could not be used from BASIC (although the kernel routines supported them), and only supported 256 [[Array (data type)|array]] elements. The [[PEEK and POKE|PEEK]] function would not work on memory locations above 49152 so as to prevent the user from viewing the copyrighted code in the system [[Read-only memory|ROMs]].

Aside from the 8K BASIC ROM, the PET also included a 4K character ROM and an 8K [[KERNAL|kernal]] ROM. The first half of the kernal contained screen editor functions (the screen editor on 80 column PETs differed from 40-column models) with the second half containing a number of function calls for tasks such as inputting and outputting data to and from different I/O devices, reading the keyboard, and positioning the cursor. In addition, the kernal ROM received system interrupts and scanned the keyboard. The kernel, an idea of John Feagans, was the first personal computer OS ROM to be a distinct entity from BASIC. The character ROM was 4K in size, containing four different 128 character tables, the uppercase/graphics character set and upper/lowercase character set, plus reverse video versions of both. This included a number of graphics characters for creating [[pseudographics]] on the screen as well as playing card symbols (reportedly because Jack Tramiel's sons wanted to play card games on the computer). On the original PET 2001, the uppercase/graphics character set and upper/lowercase character set were reversed compared to how they would be on later machines; PET owners who upgraded their machines to the BASIC 2.0 ROMs often also swapped out the character ROMs for the newer version.<ref>[http://www.6502.org/users/andre/petindex/roms.html Commodore PET ROM descriptions], (C) 1998-2013 André Fachat</ref>

[[File:Home or Personal Computers from 1977 - Commodore PET 2001, Apple II, TRS-80 Model I, together called 'Trinity77' (edited image).jpg|thumb|The Commodore PET 2001-8 alongside its rivals, the Apple II and the TRS-80 Model I|391x391px]]

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. Unlike most computer keyboards, chiclet or regular, the keys on the PET's original keyboard were also squarely aligned. This was not entirely unprecedented—previously seen in the [[Smith Premier]] typewriter—but it was unusual if not uncomfortable for experienced typists. The key tops also tended to rub off easily. Reliability was fairly poor, although that was common in many early microcomputers. Because of the poor keyboard on the PET, external replacement ones quickly appeared.{{citation needed|date=May 2014}} The PET had somewhat of a competitive advantage over its Apple II and [[TRS-80]] rivals as both were using relatively primitive [[integer BASIC]]s for their first six months on the market while the PET had a full-featured BASIC with [[floating-point arithmetic|floating-point support]], a sophisticated screen editor, and lowercase letters, the last being a feature that the two competing platforms would not have for a few years. On the other hand, Commodore were a year behind Apple and Tandy in making disk drives available for their computers.

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 white in the original 2001.

It now had a conventional, full-sized keyboard and no longer sported the built-in cassette recorder. The kernel [[Read-only memory|ROM]] was upgraded to add support for Commodore's newly introduced disk drive line.

It was offered in 8&nbsp;KB, 16&nbsp;KB, or 32&nbsp;KB models as the 2001-N8, 2001-N16, and 2001-N32 (the 8&nbsp;KB models were dropped soon after introduction). The 2001-N switched to using conventional [[dynamic random-access memory|DRAM]] instead of the 6550 (1kx4) [[static random-access memory|SRAM]] in the original model. PET 2001-8Ns had eight 2108 (8kx1) DRAMs and 2001-16Ns used sixteen 2108s. The PET 4016 used eight 4116 (16kx1) chips. All 32K PETs used sixteen 4116 chips. Finally, Commodore added a [[machine code monitor|machine-language monitor]] to the kernel ROM that could be accessed by jumping to any memory location with a [[Interrupts in 65xx processors|BRK]] instruction. It did not include a built-in [[Assembly language#Assembler|assembler]] and required the user to enter [[hexadecimal]] numbers for coding.

Commodore contacted Microsoft to upgrade BASIC for the new machines; this resulted in the soon-to-be-familiar BASIC 2.0 which removed the 256 element array limitation and had a rearranged [[zero page]].

Most bugs were fixed and IEEE-488 support in BASIC was made to be functional. The PEEK function was unblocked for memory locations above 49152. BASIC 2.0 also included an [[easter egg (media)|easter egg]] that [[Bill Gates]] personally coded, which would cause "MICROSOFT!" to appear if the user typed WAIT 6502,x (x being the number of times to display the message); this was reportedly due to a dispute with Commodore over ownership of BASIC (years later, when Microsoft developed BASIC for the [[Amiga]], one of their conditions was that Commodore credit the original authors of BASIC, so BASIC 7.0 on the [[Commodore 128]] displayed a Microsoft copyright notice). This feature was present in all 30xx series PETs. Commodore executives were unhappy when they learned about it and it was removed from BASIC on all subsequent Commodore machines. Microsoft also remained sensitive about their copyrighted code and pressured Commodore to not release any BASIC code listings to the public, although user groups eventually made disassemblies of BASIC.

Sales of the newer machines were strong, and Commodore then introduced the models to Europe. However, Philips owned a competing [[trademark]] on the PET name, so these models were renamed. 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. Later PET 3000 series machines switched to the BASIC 4.0 ROMs.