IBM PCjr Technical Reference
The IBM PCjr Technical Reference (Hardware Reference Library), Revised Edition, November 1983, is the 572-page technical reference for the IBM PCjr (4860).
What it contains
[edit | edit source]- Section 1, Introduction.
- Section 2, Base System (2-1) — the 8088 and its support devices; the 8259A interrupt controller and the PCjr interrupt assignments (2-13 to 2-17); the ROM subsystem; the input/output channel (2-21) and the input/output interfaces (2-29) including the 8255 bit map (2-30); the video and graphics subsystem (2-39 onwards) with its major component definitions, the palette (2-50), alphanumeric modes (2-54), graphics modes (2-55), the video gate array (2-63) and the CRT/processor page register (2-79); the keyboard; and the remaining on-board interfaces.
The PCjr's architecture is unlike the 5150's in several ways that matter to a repairer — the video gate array, the page register and the interrupt assignments in particular — and this is the only manufacturer document that describes them.
What it does not contain
[edit | edit source]Not a service manual: no FRU part numbers, no removal procedures, no symptom-to-FRU index and no fault codes. No text layer in the scanned sections, so searching is unreliable; work from the section and page numbers.
There is no component-level parts list. The power brick, the internal power board and the sidecar power arrangements are described functionally and by connector, not by component.
What it settles
[edit | edit source]It is the primary source for the PCjr's video gate array and palette registers, its cartridge and sidecar interfaces, and its infrared keyboard protocol — the three parts of the machine most often described wrongly from memory.
Download it here: IBM PCjr Technical Reference.pdf