IBM 5170 Technical Reference page 379

SECTION 9. IBM PERSONAL
COMPUTER COMPATIBILITY
Contents
Hardware Considerations ............................ 9-3
System Board ................................. 9-3
20Mb Fixed Disk Drive .......................... 9-4
High Capacity Diskette Drive ..................... 9-4
Adapters ..................................... 9-4
Keyboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9-4
The IBM Personal Computer AT Does Not Support .... 9-5
Application Guidelines .............................. 9-5
High-Level Language Considerations ............... 9-5
Assembler Language Programming Considerations ..... 9-6
Multi-tasking Provisions ........................ 9-11
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Interfaces ................................. 9-11
Classes ................................... 9-13
Timeouts ................................. 9-15
SYS REQ Key ................................ 9-15
Subsystem Structure ........................ 9-15
Subsystem Startup and Lockout ........ . . . . . . .. 9-16
SYS REQ Key Functions ..................... 9-17
SYS Key Interfaces ......................... 9-18
Copy Protection .............................. 9-22
Bypassing BIOS ............................ 9-22
Diskette Drive Differences ................... 9-22
Write Current ............................. 9-23
Machine-Sensitive Code ........................ 9-23
Compatibility 9-1