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IBM PCjr

4860-004 · 4860-067 · 1984–1985 · desktop

Specifications

Cpu: Intel 8088, 4.77 MHz
Ram: max: 128 KB on the motherboard, up to 640 KB with third-party sidecar RAM expansions · base: 64 KB (Model 4860-004) or 128 KB (Model 4860-067)
Ports: 2x cartridge slots · 2x joystick ports · Light pen port · Cassette port · RGB monitor port · Composite video port · RF television output · Audio out · Wired keyboard port · Infrared keyboard sensor · Serial port · Side expansion (sidecar) connector
Display: Enhanced version of the PC's CGA: composite/RF out, up to 16 colors at 160x200 or 640x200 monochrome, better than the 5150's CGA card
Storage: base: No internal drive on the 64 KB model (cartridge slots only) · options: 5.25" 180 KB/360 KB floppy drive (standard on the 128 KB model, optional add-on for the base model) · 2x ROM cartridge slots (up to 64 KB per cartridge)
Os Support: latest: PC DOS 3.3 ran with third-party memory and driver workarounds; the machine's non-standard architecture blocked most later PC-compatible software · shipped: PC DOS 2.1 or Cartridge BASIC in ROM
Release Price: $669 (64 KB model) / $1,269 (128 KB model with floppy drive)

Upgrade paths

RAM

640 KB via third-party side expansion (sidecar) memory modules · The side expansion port stacked sidecar modules, but IBM's own memory options were limited and pricey, so most upgrades came from third parties like Tecmar.

~$150-$300 at the time for a sidecar RAM expansion

MODERATE

keyboard

Wired keyboard cable replacing the infrared link · The chiclet-keyed infrared keyboard was widely disliked; IBM later shipped an improved keyboard, and owners commonly used the wired port instead of the flaky IR sensor.

EASY