IBM PC AT 5170 Technical Reference (September 1985)
The IBM Personal Computer AT Technical Reference, September 1985, IBM part number 6280070, is the 500-page revised technical reference for the IBM PC AT 5170. It is the edition to use for any AT built after early 1985: it covers all planar types, including the Type 2 board, and the 06/10/85 BIOS.
What it contains
[edit | edit source]- Section 1, System Board — memory and the 80286, system performance, direct memory access (1-9), system interrupts with the hardware interrupt listing and interrupt sharing (1-13 to 1-21), system timers, the system clock (1-23), the ROM subsystem, and onward through the I/O channel, the other planar circuits, specifications, connectors and the logic diagrams.
- Section 2, Coprocessor; Section 3, Power Supply; Section 4, Keyboard; Section 5, System BIOS; Section 6, Instruction Set.
The reorganisation between the two AT editions is substantial — DMA and interrupts move and expand — so page references taken from one edition will not match the other.
What it does not contain
[edit | edit source]Not a service manual: no FRU part numbers, no removal procedures and no symptom-to-FRU index. The logic diagrams are design drawings without a populated bill of materials.
What it settles
[edit | edit source]This is the edition that settles which AT board you are looking at. The Type 1 and Type 2 (Baby AT) planars differ in layout, memory arrangement and BIOS, and the earlier March 1984 edition documents only the Type 1. Identify the board first, then pick the edition.
Download it here: IBM PC AT 5170 Technical Reference Sep85.pdf