The IBM PCjr was released in March 1984 with a price of $1300, and was intended to be IBM's low-cost entry into the home computer and small business markets. Unfortunately, it proved to be too expensive for it's intended markets considering what it offered and barely lasted one year on the market. Among the drawbacks of the system was it's lack of expandibility, it's poorly designed 'chicklet' keyboard, and the fact that all of the connectors for such things as serial and monitor connections on the rear were nonstandard. It also had three prorietary 8bit expansion slots internal, all of which could only be used for very specific things. One was for the 64k memory expansion, the 2nd for a non-Hayes compatible internal modem, and the third was used for the floppy disk controller. All other expansion was by way of external sidecards, plugged into a connector on the side of the machine. On the plus side, the machine was very small and lightweight, and it's keyboard was wireless, using an infra-red sensor on the front of the machine. It's BASIC also was more powerful than the GW-BASIC shipping with IBM's more expensive machines. It also had built-in an improved version of CGA graphics with more modes and colors. It should be noted that the PCjr was only somewhat compatible with IBM's PC-XT as far as software was concerned. The PCjr was abandoned by IBM in April 1985.
The machine had an 8086 cpu running at 4.77mhz and shipped with 64k
of RAM, 32k of which was shared by the video system. One could then expand
it to 128k by adding the internal 64k ram expansion, and then upgrade it to
256k by adding a 128k memory expansion sidecar. The PCjr also had two
cartridge slots located just below the floppy drive on the front panel. A
few programs, such as the cartridge version of Lotus 1-2-3, actually used
both cartridge ports.
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