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IBM PS2 Model 50 Technical Reference (October 1990)

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The IBM Personal System/2 Model 50 Technical Reference is IBM's 66-page model-specific interface reference for the PS/2 Model 50 (8550), Third Edition, October 1990 (copyright 1989, 1990). It covers both the Type 1 and Type 2 system boards, which programs tell apart by model byte FC, submodel 04 and revision 00 (Type 1) or 03 (Type 2) (Figure 1-1, p. 1-3). The preface says it is to be used with the Hardware Interface Technical Reference volumes Architectures and Common Interfaces and the PS/2 and PC BIOS Interface Technical Reference. Vertical bars in the margin mark changes; the first edition, May 1988, is also hosted.

Contents

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From the contents page (p. vii):

  • Section 1, System Overview (p. 1-1): description and model bytes, system board features, block diagram, I/O address map, specifications (performance for Type 1 and Type 2, physical p. 1-9, acoustics p. 1-10), and a power supply section added in this edition (pp. 1-11 to 1-12): outputs, output protection and voltage sequencing.
  • Section 2, Programmable Option Select (p. 2-1): POS address map, card selected feedback (hex 0091), system board enable/setup (hex 0094), POS registers 2 and 3 (hex 0102, 0103), adapter enable/setup (hex 0096).
  • Section 3, System Board (p. 3-1): Micro Channel implementation and exception reporting, adapter identification, central arbiter, ROM and RAM, memory connectors, real-time clock and CMOS RAM (p. 3-12), NMI, system control ports B and A, power-on password (p. 3-27), Type 2 serial port controller and hardware compatibility (p. 3-28).
  • Index.

What this manual does not contain

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It is a programming and interface reference: no FRU numbers, removal procedures, symptom index, schematics or component values. Material common to the PS/2 family is in the Hardware Interface Technical Reference volumes.

What it settles

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From the power supply section (pp. 1-11 to 1-12):

  • The system-board voltages are +5, +12 and −12 V; the drives receive +5 and +12 V. There is no −5 V output.
  • Maximum current from the auxiliary device port is 300 mA and from the keyboard port 275 mA, both at +5 V (Figure 1-9).
  • Each Micro Channel connector may draw 1.6 A at +5 V, 0.175 A at +12 V and 0.040 A at −12 V (Figure 1-10).
  • A short on any output, or an internal overvoltage before any output exceeds 130 % of nominal, latches all outputs off. The supply restarts only after the fault is removed and the power switch has been off for at least ten seconds. At power-on the outputs track within 50 ms of each other at their 50 % points.

The physical specifications (Figure 1-7, p. 1-9) give 9.55 kg, heat output 150 W (512 BTU/hour), automatic range selection between 90-137 V and 180-265 V, and 0.11-0.25 kVA input. The May 1988 edition gives 144.8 W heat output.

Pages that cite this document

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Download: IBM PS2 Model 50 Technical Reference Oct90.pdf

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