Section 1. System Board - IBM 5170 Technical Reference

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SECTION 1. SYSTEM BOARD
Contents
Description 1-3
Memory 1-4
Microprocessor ..•••..........••••••••••••••••••.• 1-4
Real-Address Mode .......................... 1-4
Protected Mode ............................. 1-5
System Performance •.••••......... .•..••••
e,
1-7
System Timers ..••••.............•••••••.••.••.... 1-8
System Interrupts ...•.•.•.......•.......•......•. 1-10
ROM Subsystem
.................................
1-11
RAM Subsystem
1-12
Direct Memory Access (DMA) .•••••.............•.. 1-12
Programming the 16-Bit DMA Channels. . . . . . . .. 1-14
I/O Channel ••••••.••.••......•...••••••••••.•.. 1-15
I/O Channel Signal Description ............... 1-22
Other Circuits .•••••.............••••••.••••••... 1-30
Speaker ..................................... 1-30
Jumper ..................................... 1-30
Type of Display Adapter Switch .................. 1-31
Variable Capacitor ............................ 1-31
Keyboard Controller ........................... 1-31
Receiving Data from the Keyboard ............. 1-32
Scan Code Translation ....................... 1-32
Sending Data to the Keyboard ................. 1-37
Inhibit ................................... 1-37
Keyboard Controller System Interface .......... 1-37
System Board 1-1