IBM PCjr
The IBM PCjr (pronounced "PC junior") was a home computer produced and marketed by IBM from March 1984 to May 1985, intended as a lower-cost variant of the IBM PC with hardware capabilities better suited for video games, in order to compete more directly with other home computers such as the Apple II and Commodore 64. It retained the IBM PC's 8088 CPU and BIOS interface, but provided enhanced graphics and sound, ROM cartridge slots, built-in joystick ports, and an infrared wireless keyboard. The PCjr supported expansion via "sidecar" modules, which could be attached to the side of the unit. Despite widespread anticipation, the PCjr was ultimately unsuccessful in the market. It was only partially IBM compatible, limiting support for IBM's software library, its chiclet keyboard was widely criticized for its poor quality, expandability was limited, and it was initially offered with a maximum of 128KB of RAM, insufficient for many PC programs. The PCjr came in two models: 4860-004 - 64 KB of memory, priced at US1,269 () The PCjr was manufactured for IBM in Lewisburg, Tennessee by Teledyne. A related machine, the IBM JX, was sold in the Japan, Australia and New Zealand markets. The PCjr chassis is made entirely of plastic, unlike the all-steel chassis of the IBM PC. A 5.25" front bay allows the installation of a 180/360K floppy disk drive. The internal floppy drive was a half-height Qume 5.25" unit; IBM also used these drives in the PC Portable, but the PCjr units were specially equipped with a small fan to prevent overheating since the computer did not have a case fan. The front of the PCjr exposes a pair of cartridge slots in which the user can insert software on ROM cartridges, as was common with other home computers. When a ROM cartridge is inserted, the machine automatically restarts and boots off of the ROM, without requiring the user to manually reboot. Cartridges can also replace the system BIOS and other firmware.
