IBM Personal System/2 50 Use and care manual

First Edition (May, 1988)
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Preface
The Technical Reference library is intended for those who develop
hardware and software products for IBM Personal Computers and
IBM Personal System/2. Users should understand computer
architecture and programming concepts.
This technical reference provides hardware and software interface
information for the IBM Personal System/2 Model 50 and should be
used with the following publications:
IBM Personal Systeml2 Hardware Interface Technical Reference
IBM Personal Systeml2 and Personal Computer BIOS Interface
Technical Reference
This manual consists of the following sections:
Section 1, "System Overview," describes the system, features
and specifications.
Section 2, "Programmable Option Select," describes registers
used for configuration.
Section 3, "System Board," describes the system specific
hardware implementations.
Warning: The term "Reserved" describes certain signals, bits, and
registers that should not be changed. Use of reserved areas can
cause compatibility problems, loss of data,
or permanent damage to
the hardware. When the contents of a register are changed, the state
of the reserved bits must be preserved. When possible, read the
register first and change only the bits that must be changed.
For information about components or devices not described in this
manual, refer to the Hardware Interface Technical Reference.
Information about diskette drives, fixed disk drives, adapters, and
external options are in separate option technical references.
III

Notes:
Iv

Contents
Section 1. System Overview ........................ 1-1
Description .................................... 1-3
System Board Features ............................ 1-3
System Board Block Diagram ........................ 1-5
System Board I/O Address Map ...................... 1-6
Specifications .................................. 1-7
Section 2. Programmable Option Select ......... . . . . . . . . 2-1
Description .................................... 2-3
POS Address Map .................... . . . . . . . . . . .. 2-5
Card Selected Feedback ........................... 2-6
System Board Setup .............................. 2-6
System Board Enable/Setup Register (Hex 0094) ......... 2-7
System Board POS Register 2 (Hex 0102) .............. 2-8
System Board POS Register 3 (Hex 0103) .............. 2-9
Adapter Enable/Setup Register (Hex 0096) ............ 2-10
Section 3. System Board ........................... 3-1
Description .................................... 3-3
Micro Channel .................................. 3-3
Adapter Identification ........................... 3-3
Central Arbiter ................................ 3-3
Memory ...................................... 3-7
Read-Only Memory Subsystem ..................... 3-7
Random Access Memory Subsystem ................. 3-7
Real-Time Clock/Complementary Metal-Oxide Semiconductor
RAM ..................................... 3-12
Miscellaneous System Functions ... . . . . . . . . . . . . . . . . .. 3-24
Nonmaskable Interrupt . . . . . . . . . . . . . . . . . . . . . . . . .. 3-24
System Control Port B (Hex 0061) .................. 3-24
System Control Port A (Hex 0092) .................. 3-26
Power-On Password
........................... 3-28
Type 2 Serial Port Controller
....................... 3-29
Hardware Compatibility ........................... 3-29
Index ........................................ X-1
v

Notes:
vi

Figures
1-1. Model and Submodel Bytes ................... 1-3
1-2. System Board Devices and Features ............. 1-4
1-3. System Board ............................ 1-5
1-4. System Board I/O Address Map ................ 1-6
1-5. Performance Specifications -Type 1 System Board .. 1-7
1-6. Performance Specifications -Type 2 System Board .. 1-8
1-7. Physical Specifications ...................... 1-9
2-1. POS I/O Address Map ....................... 2-5
2-2. Card Selected Feedback Register (Hex 0091) ....... 2-6
2-3. System Board Enable/Setup Register (Hex 0094) ..... 2-7
2-4. System Board POS Register 2 (Hex 0102) .......... 2-8
2-5. Parallel Port Select Bits ..................... 2-8
2-6. System Board POS Register (Hex 0103) ........... 2-9
2-7. Adapter Enable/Setup Register (Hex 0096) ........ 2-10
3-1. Arbitration Bus Priority Assignments ............. 3-4
3-2. Arbitration Register, Write to Hex 0090 ........... 3-5
3-3. Arbitration Register, Read Hex 0090 ............. 3-5
3-4. System Memory Map ....................... 3-8
3-5. System Board Memory Connector, Type 1 ......... 3-9
3-6. System Board Memory Connector, Type 2 ........ 3-10
3-7. Presence Detect Encoding ................... 3-11
3-8. RT/CMOS RAM Address Map ................. 3-12
3-9. RT/CMOS Address Register and NMI Mask (Hex 0070) 3-13
3-10. RT/CMOS Data Register (Hex 0071) ............. 3-13
3-11. Real-Time Clock Bytes ..................... 3-15
3-12. Status Register A ......................... 3-16
3-13. Status Register B ......................... 3-16
3-14. Status Register C ......................... 3-18
3-15. Status Register D ......................... 3-18
3-16. Diagnostic Status Byte ..................... 3-19
3-17. Diskette Drive Type Byte .................... 3-20
3-18. Diskette Drive Type Byte (Bits 7 - 4) ............ 3-21
3-19. Diskette Drive Type Byte (Bits 3 - 0) ............ 3-21
3-20. Equipment Byte .......................... 3-22
3-21. Equipment Byte (Bits 7, 6) ................... 3-22
3-22. Equipment Byte (Bits 5, 4) ................... 3-22
3-23. System Control Port B (Write) ................. 3-25
3-24. System Control Port B (Read) ................. 3-25
3-25. System Control Port A (Hex 0092) .............. 3-26
vII

Notes:
vIII

Section 1. System Overview
Description .................................... 1-3
System Board Features
............................ 1-3
System Board Block Diagram
........................ 1-5
System Board I/O Address Map
...................... 1-6
Specifications
.................................. 1-7
Model 50 System Overview 1-1

Notes:
1-2 Model 50 System Overview