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P4 verification: real documentation page - title as printed, part/form number, edition, contents, honest gaps, what it settles, cross-links
Contents checked against the manual; note comment-form number 1502494 and bundled Update 4; drop unsupported "frequently mis-stated" claims; sense levels; citing pages
 
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The '''IBM Personal Computer AT Technical Reference''', '''First Edition (March 1984)''', '''IBM part number 1502243''', is the 462-page technical reference for the [[IBM PC AT (5170)|IBM PC AT 5170]] as originally shipped: the '''Type 1''' system board with the 01/10/84 BIOS.
The '''Technical Reference''' for the [[IBM PC AT (5170)|IBM Personal Computer AT (5170)]], First Edition (March 1984), is IBM's design reference for the AT as first shipped, with the type 1 system board. Minuszerodegrees.net lists its part number as 1502243; the reader's comment form at the back of this scan is numbered 1502494. The hosted PDF has 462 pages. Its BIOS listing is headed "TEST1 11/28/83", the source for the first AT BIOS, released as 01/10/84. The scan includes Technical Reference Update Number 4 (6138321, August 24, 1984), which replaces pages 1-27, 1-28, 1-28.1 and 1-28.2.


== What it contains ==
== Contents ==


* '''Section 1, System Board (1-1)''' — memory and the 80286, '''system performance''' (1-7), system timers, system interrupts with the hardware interrupt listing and '''interrupt sharing''' (1-14), the ROM and RAM subsystems, DMA, the '''I/O channel''' (1-15 to 1-30), other circuits including the speaker, the jumper, the '''type of display adapter switch''' (1-31), the '''variable capacitor''' (1-31) and the keyboard controller, then specifications (1-55), connectors (1-57) and the '''logic diagrams''' (1-61).
From the manual's contents list (pp. vii to ix):
* '''Section 2, Coprocessor''' — the 80287.
* '''Section 3, Power Supply (3-1)''' — inputs, outputs, output protection, the '''dummy load''', output voltage sequencing, '''no-load operation''', the power-good signal, fan-out and the connectors.
* '''Section 4, Keyboard''' — the interface, key-code scanning, the buffer, the power-on reset and basic assurance test, commands in both directions, '''key scan codes''', clock and data signals, the keyboard layout and the connector specification.
* '''Section 5, System BIOS''' — usage, keyboard encoding and the BIOS listing.
* '''Section 6''' — the 80286 instruction set.


== What it does not contain ==
* Section 1, System Board (1-1): description (1-3), memory and microprocessor (1-4), system performance (1-7), system timers (1-8), system interrupts (1-10), ROM and RAM subsystems (1-11, 1-12), DMA (1-12), the I/O channel (1-15), other circuits (1-30) including the speaker, the jumper, the display adapter switch and the variable capacitor (1-31) and the keyboard controller, real-time clock and CMOS RAM information (1-45), specifications (1-55), connectors (1-57) and logic diagrams (1-61)
* Section 2, Coprocessor (2-1): the 80287
* Section 3, Power Supply (3-1): inputs and outputs (3-3), output protection and the dummy load (3-4), output voltage sequencing (3-4), no-load operation and the power-good signal (3-5), fan-out and connectors (3-6)
* Section 4, Keyboard (4-1): interface, key code scanning, buffer, power-on reset and basic assurance test (4-4), commands from the system (4-5), scan codes (4-10), clock and data signals (4-14), layout (4-16), connector (4-23)
* Section 5, System BIOS (5-1): BIOS usage, keyboard encoding and extended codes, and the listing
* Section 6, Instruction Set (6-1): the 80286 and 80287 instructions
* Section 7, Characters, Keystrokes and Color (7-1)
* Section 8, Communications (8-1)
* Section 9, IBM Personal Computer Compatibility (9-1): hardware considerations, including what the AT does not support (9-5), and application guidelines
* Glossary, bibliography and index


Not a service manual: no FRU part numbers, no removal procedures, no symptom-to-FRU index. The logic diagrams are design drawings without a populated bill of materials.
== What this manual does not contain ==


It documents '''only the Type 1 board and the 01/10/84 BIOS'''. If your AT has a Type 2 (Baby AT) planar or a later BIOS, use the [[IBM PC AT 5170 Technical Reference (September 1985)|September 1985 edition]] instead — the differences are real and this edition will mislead you.
* It is not a service manual. It has no FRU part numbers, removal procedures or problem isolation charts; see [[IBM Hardware Maintenance Service (March 1986)]] and [[IBM Personal Computer Family Service Information Manual]].
* The logic diagrams have no parts list or board placement drawing.
* Only the type 1 system board and the first BIOS. The type 2 board and the 06/10/85 BIOS are in the [[IBM PC AT 5170 Technical Reference (September 1985)|September 1985 edition]]. Neither edition covers the 8 MHz type 3 board.


== What it settles ==
== What it settles ==


Two AT-specific details that are frequently mis-stated elsewhere and are settled here:
* The AT power supply's dc load requirements, the 1-second minimum off time, the 100 to 500 ms Power Good delay and the minimum sense levels of +4.5, −3.75, +10.8 and −10.4 V (pp. 3-3 to 3-6). IBM's 1989 service manual gives −4.3 V and −10.2 V for the negative rails.
* The dummy load and no-load behaviour: with no load the supply may switch off and need a power-on cycle, without damage (pp. 3-4, 3-5).


* '''The "variable capacitor" (1-31)''' is a real, documented part of the AT planar, not a modification. It appears in Section 1 alongside the jumper and the display-type switch.
== Pages that cite this document ==
* '''The dummy load and no-load operation''' clauses in Section 3 explain why an AT supply may behave oddly on the bench with nothing connected: IBM specifies its behaviour under no load explicitly, so a supply that misbehaves unloaded is not necessarily faulty.


<pdf> File:IBM PC AT 5170 Technical Reference Mar84.pdf </pdf>
* [[IBM PC AT Maintenance Guide]]
* [[IBM PC AT Capacitor Replacement Guide]]


Download it here: [[:File:IBM PC AT 5170 Technical Reference Mar84.pdf|IBM PC AT 5170 Technical Reference Mar84.pdf]]
<pdf>File:IBM PC AT 5170 Technical Reference Mar84.pdf</pdf>
 
Download: [[:File:IBM PC AT 5170 Technical Reference Mar84.pdf|IBM PC AT 5170 Technical Reference Mar84.pdf]]


== Related pages ==
== Related pages ==


* [[IBM PC AT (5170)]] &middot; [[IBM PC AT Maintenance Guide]] &middot; [[IBM PC AT Troubleshooting Guide]] &middot; [[IBM PC AT Capacitor Replacement Guide]]
* [[IBM PC AT (5170)]], [[IBM PC AT Maintenance Guide]], [[IBM PC AT Troubleshooting Guide]], [[IBM PC AT Capacitor Replacement Guide]]
* [[IBM PC AT 5170 Technical Reference (September 1985)]] &mdash; the later edition, covering all board types
* [[IBM PC AT 5170 Technical Reference (September 1985)]]
* [[IBM PC 5150 Technical Reference]] &middot; [[IBM PC XT Technical Reference (First Edition)]]
* [[IBM PC 5150 Technical Reference]], [[IBM PC XT Technical Reference (First Edition)]]


[[Category:IBM Service Manuals]]
[[Category:IBM Service Manuals]]
[[Category:Service Manuals]]
[[Category:Service Manuals]]

Latest revision as of 20:47, 30 September 2026

The Technical Reference for the IBM Personal Computer AT (5170), First Edition (March 1984), is IBM's design reference for the AT as first shipped, with the type 1 system board. Minuszerodegrees.net lists its part number as 1502243; the reader's comment form at the back of this scan is numbered 1502494. The hosted PDF has 462 pages. Its BIOS listing is headed "TEST1 11/28/83", the source for the first AT BIOS, released as 01/10/84. The scan includes Technical Reference Update Number 4 (6138321, August 24, 1984), which replaces pages 1-27, 1-28, 1-28.1 and 1-28.2.

Contents

[edit | edit source]

From the manual's contents list (pp. vii to ix):

  • Section 1, System Board (1-1): description (1-3), memory and microprocessor (1-4), system performance (1-7), system timers (1-8), system interrupts (1-10), ROM and RAM subsystems (1-11, 1-12), DMA (1-12), the I/O channel (1-15), other circuits (1-30) including the speaker, the jumper, the display adapter switch and the variable capacitor (1-31) and the keyboard controller, real-time clock and CMOS RAM information (1-45), specifications (1-55), connectors (1-57) and logic diagrams (1-61)
  • Section 2, Coprocessor (2-1): the 80287
  • Section 3, Power Supply (3-1): inputs and outputs (3-3), output protection and the dummy load (3-4), output voltage sequencing (3-4), no-load operation and the power-good signal (3-5), fan-out and connectors (3-6)
  • Section 4, Keyboard (4-1): interface, key code scanning, buffer, power-on reset and basic assurance test (4-4), commands from the system (4-5), scan codes (4-10), clock and data signals (4-14), layout (4-16), connector (4-23)
  • Section 5, System BIOS (5-1): BIOS usage, keyboard encoding and extended codes, and the listing
  • Section 6, Instruction Set (6-1): the 80286 and 80287 instructions
  • Section 7, Characters, Keystrokes and Color (7-1)
  • Section 8, Communications (8-1)
  • Section 9, IBM Personal Computer Compatibility (9-1): hardware considerations, including what the AT does not support (9-5), and application guidelines
  • Glossary, bibliography and index

What this manual does not contain

[edit | edit source]

What it settles

[edit | edit source]
  • The AT power supply's dc load requirements, the 1-second minimum off time, the 100 to 500 ms Power Good delay and the minimum sense levels of +4.5, −3.75, +10.8 and −10.4 V (pp. 3-3 to 3-6). IBM's 1989 service manual gives −4.3 V and −10.2 V for the negative rails.
  • The dummy load and no-load behaviour: with no load the supply may switch off and need a power-on cycle, without damage (pp. 3-4, 3-5).

Pages that cite this document

[edit | edit source]

Download: IBM PC AT 5170 Technical Reference Mar84.pdf

[edit | edit source]
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