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In the early 1980s, Commodore found itself engaged in a price war in the home computer market. The hot-selling VIC-20 was a design accident resulting from MOS Technology designing a videogame chip it couldn't sell, and companies like Texas Instruments and Timex Corporation undercutting the price of Commodore's PET line. The Commodore 64, the first 64 KB computer to sell for under US$600, was another salvo in the price war but it was far more expensive to make than the VIC-20 because it used discrete chips for video, sound, and I/O. Commodore president Jack Tramiel wanted a new computer line that would use fewer chips and at the same time address some of the user complaints about the VIC and C64.
Commodore's third salvo – which, as it turned out, was fired just as most of Commodore's competition was leaving the home computer market – was the C116, C16, and Plus/4. All three computers used a MOS 7501 CPU ( 6502The MOS Technology 6502 is an 8-bit microprocessor designed by MOS Technology in 1975. When it was introduced it was the least expensive full featured CPU on the market by far, at about 1/6th the price, or less, of competing designs from larger companies compatible but ~75% faster) and a MOS 7360 "TED" all-in-one video, sound, and I/O chip. The Plus/4's design is thus philosophically closer to that of the VIC-20 than of the C64.
The Plus/4 was the flagship computer of the line. The Plus/4 had 64 KB of memory while the C16 and 116 had 16 KB. The Plus/4 had built-in software, whereas the others did not. The Plus/4 and C16 had full-travel keyboards; the 116 used a rubber chiclet keyboard like less-expensive Timex-Sinclair computers and the original IBM PCjr. The C116 was only sold in Europe. All of the machines were distinguished by their dark gray cases and light gray keys.
The Plus/4 was introduced in June 1984 and priced at US$299. It was discontinued in 19851985 is a common year starting on Tuesday. Events January events January 1 Creation of the Internet's Domain Name System. January 17 British Telecom annouces they are going to abolish the famous red telephone boxes. January 23 A debate in the House of Lor. It is not completely clear whether Commodore's intent was to eventually totally replace the C64 with the Plus/4, or whether they wanted to attempt to expand the home computer market and sell the Plus/4 to users who were more interested in serious applications than gaming. However, the Plus/4 succeeded at neither and quickly disappeared.
The TED offered 121-color (15 colors * 8 luminance levels + black) video, which was revolutionary for its time, and 320×200 video resolution, which was standard for computers intended to be capable of connecting to a television. The Plus/4's memory layout gave it a larger amount of user-accessible memory than the C64, and its BASIC programming languageCommodore 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 was vastly improved, adding sound and graphics commands as well as looping commands that improved program structure. Commodore released a high-speed floppy diskA floppy disk is a data storage device that comprises a circular piece of thin, flexible (hence "floppy") magnetic storage medium encased in a square or rectangular plastic wallet. Floppy disks are read and written by a floppy disk drive or FDD not to be drive for the Plus/4, the Commodore 1551The Commodore 1551 was a floppy disk drive for the Commodore Plus/4 home computer. It resembled a charcoal-colored Commodore 1541 and plugged into the cartridge port, providing faster access than the C64/1541 combination. Aside from faster access, the dri, which offered much better performance than the C64/ 1541The Commodore 1541 (originally called VIC-1541 was the best-known floppy disk drive for the Commodore 64 home computer. The 1541 was a single-sided 166 kilobyte drive for 5¼" disks. The 1541 followed the previous Commodore 1540 (meant for the VIC-20). combination because its data cable plugged into the cartridge port to facilitate direct memory accessDirect memory access (DMA allows certain hardware subsystems within a computer to access system memory for reading and/or writing independently of the main CPU. Examples of systems that use DMA: Hard Disk Controller, Disk Drive Controller, Graphics Card,, rather than using a serial bus.
Unlike the C64, the Plus/4 had a built-in MOS 6551 UART chip (the C64 emulated the 6551 in software). This allowed the Plus/4 to use high-speed modems without additional hardware or software tricks (the C64 required specially written software to operate at 2400 bit/s). However, since most people only could afford 300 or 1200 bit/s modems in 1984, this was not an issue. The Plus/4 keyboard had a separately placed "diamond" of four cursor keys, presumably more intuitive in use than the VIC's and C64's two shifted cursor keys. Also, for serious programmers, the Plus/4 featured a ROM-resident machine code monitor (rekindling a tradition from the first Commodore computers, the PET/CBM series).
While the C64 had the advertised 64 KB of RAM installed, its largest contiguous block of memory was only about 38 KB in size. The Plus/4's memory map was less fragmented, with a large 59K block available for BASIC or machine language programs. In addition, the Plus/4's CPU was about 75% faster than the C64's.