Computer demo/display notes

by George Page



The first computer marketed by CBM. It had been developed by MOS Technologies prior to MOS' acquisition by CBM (1977).

It was basically a bare-bones 6502 "trainer". 1K RAM, 2K ROM. With the optional KIM3B memory board & KIM4 motherboard were expandable up to 65K. Just a small board with 6 LED digital displays, and a 23 key HEX keypad. Sold for $245-$275 in June of '78. By Nov of '78 was advertised by CBM/MOS for $179.95. Claimed to have great documentation. Just edge connectors to hook to P/S and other expansion boards. Also marketed as a kit. Survived for a surprisingly long time. (mid-80's?).


Was the first computer developed and marketed by CBM (1977). Evolved into a number of different models. First were the PET 2001-8K and (optional) 4k machines. Small "chiclet" style keys, built-in cassette for program storage and built-in monitor. 6502 based.

Officially PET stood for Personal Electronic Transactor, but there were a number of other variants and stories, such as the one that claimed it was to cash-in on the pet rock popularity. Or using Chuck Peddle's (the designer) name in there somehow.

CBM 2001/B was a business version with full size keyboard. PET 2001/N was same as CBM 2001/B except displayed graphics symbols on front of keyboard. All could be expanded up through 32K. 40 column screen. Originally BASIC 1, went up to 2, renamed 3xxx with V3.

External cassettes could be connected to all (2 in all but PET 2001-4/8K's). Also could use disk or printer if Rev3 ROM's onboard. Had IEEE-488 interface, parallel user port, and memory expansion port.


The Microcomputer Development System (MDS) 6500 was a customized PET 2001/N32 with a built-in assembler. It came with a companion MDS6500 2040 disk drive. Less than 500 ever made.

The CBM 4000 and 8000 series

CBM 4000's & 8000's came out in '80 & '81. Larger case, Basic v4, 8xxx's had 12" 80 column screen. Otherwise pretty much the same as the earlier ones. Some software incompat between some 4xxx & 8xxx machines.

The SuperPET (SP9000)

SuperPET (SP9000) '81? was a special 8xxx machine with many built-in options designed in conjunction with The University of Waterloo in Canada. It had two (6502 or 6809) microprocessors built-in, 32K + 64K of RAM. Had true RS232 port capable of 9600 baud. Came with a number of different programming languages. 4 fonts built-in. The RAM could be "write-protected" using a combination of hardware/software means.

Vic 20

Introduced in '82. Small keyboard, external modulator, 22 column video output (changable by software). 16 colors. 4 voices (3 notes, 1 noise). Several different variants and keyboards. 2 different power supply types. 3583 bytes free, expandable to 64K. First cheap home computer with these capabilities and full size keyboard. Basic 2.0 Had user(pseudo RS232) port, and expansion/cartridge port. Also cassette and serial ports. One joystick port.

Commodore 64

Also introduced in '82, took the home computer world by storm. 38911 bytes free, 16 colors, 40 columns with built-in modulator. 3 voice SID. At least 7 different boards including the newer, more modern looking 64C. Several different keyboards and 2 diffent case logo's on the old style case. (Same as used in the VIC20, and directly interchangeable). Two different video sockets used-newer is 8 pin that gives sharper monitor display (and power plug doesn't fit). Same user, serial and cassette ports as VIC. Different exp/cart port. 2 joystick ports. Basic 2.0.

Educator 64 (PET64, 4064)

Educator64's-two models-one in 64 case, one in PET style case-no sound, color or sprites. Primarily for school use. Used modified C64 circuit boards-primarily "returns".

The B and P series

The B & P series emerged in '83. These were primarily business machines, and were available either with or without a built-in monochrome monitor as LP and HP models. In addition, the HP's could contain a dual disk drive setup. Sleek, modern looking machines, with many new features. Used Basic 4.0.

The B128-80 and B256-80 (700(lp) 710(hp) and 720) were 80 column monochrome machines. Each had a 6509 microprocessor with an 8088 optional on the 128 & standard on the 256. In addition the 256 model had an optional 8087 math co-processor chip. They each had an external RS232C port capable of 19,200 with the built-in 6551 ACIA chip. RAM was expandable to 256K internal and 704K externally.

The C128-40 was similar, but had 16 colors and built-in modulator. 320 X 200 pixel bit mapped graphics.

All had the 6581 SID chip, with three voices and direct audio output, and a true RS232 port using a 6551 ACIA capable of 19,200 baud.

The Executive 64

The SX64 was introduced in '83. Combined a 64, power supply, disk drive and monitor in one "portable" case. Lacked the cassette port of a standard 64. (ROM rewritten to default to the built-in drive). Cartridge port not 100% identical either. Also made in a DX64 model in limited numbers (2 drives). A number of homebrew DX mods made. Didn't catch on too well at first, and large numbers were liquidated by a mail order outfit, along with the add-on drive kits.

Commodore 16 and plus/4

C16 & PLUS/4 were introduced in '84 as part of the 264/364 series. These were 40 column machines using Basic 3.5. ESC/R would shrink down to 38 columns as some TV's couldn't handle the 40 col. Built-in modulators. Both had serial bus same as VIV/64, but used different cartridge/exp, cassette and joystick ports. Also used slightly different method of datasette recording. 16 colors X 8 intensity levels. 1 tone, 1 either tone or noise voices. 320 X 200? Help key. Modulator. Neither became too popular.

The 16 looked identical to a VIC20/64, but keyboard was not directly interchangeable. 12,277 free. Included a "Help" key. 16 colors X 8 levels. 1 tone, 1 either tone or noise sound voices. No user port.

The Plus/4 was a totally new case style and had 4 built-in software utilities. Word Processor, Spread Sheet, Database and a Graphics program. It a built-in 6551 ACIA capable of 19,200, but required an adaptor to hook to a standard RS232 cable. 64K (60671 free). 320 X 200 pixels. Built-in M/L Monitor.

Commodore 128

'85... 40/80 col. Monitor. Modulator. 64/128/Z-80 (CP/M). 128K... It was first designed to be 256 kilobytes by default, and upgradable to 1 megabyte. Alas, typical of Commodore, it was downgraded to 128 kilos, and internal memory expansions were made very difficult. Commodore introduced the REU (RAM Expansion Unit) to compensate for this.

There were also two different versions of the C128 with a built-in 1571 drive. The C128D used the normal C128 motherboard, whereas the C128DCR has a completely redesigned motherboard with integrated floppy controller.

Commodore 65 (C64DX)

Scheduled in '91 but canned. Dozens or even thousands of prototypes were made. Commodore liquidated one of its warehouses in 1993, and the C65 prototypes were rapidly sold out by some retailers.