8-21
INTERRUPT CONTROL UNIT
Figure 8-12. Poll Status Register
8.4.7
End-of-Interrupt (EOI) Register
The End-of-Interrupt register (Figure 8-13) issues an End-of-Interrupt (EOI) command to the In-
terrupt Control Unit, which clears the In-Service bit for the associated interrupt. An interrupt han-
dler typically ends with an EOI command. There are two types of EOI commands: nonspecific
and specific. A nonspecific EOI simply clears the In-Service bit of the highest priority interrupt.
To issue a nonspecific EOI command, set the NSPEC bit. (Write 8000H to the EOI register.)
A specific EOI clears a particular In-Service bit. To issue a specific EOI command, clear the
NSPEC bit and write the VT4:0 bits with the interrupt type of the interrupt whose In-Service bit
you wish to clear. For example, to clear the In-Service bit for INT2, write 000EH to the EOI reg-
ister. The timer interrupts share an In-Service bit. To clear the In-Service bit for any timer inter-
rupt with a specific EOI, write 0008H (interrupt type 8) to the EOI register.
Register Name:
Poll Status Register
Register Mnemonic:
POLLSTS
Register Function:
Read to check for pending interrupts when polling
Bit
Mnemonic
Bit Name
Reset
State
Function
IREQ
Interrupt
Request
0
This bit is set to indicate a pending interrupt.
VT4:0
Vector Type
0
Contains the interrupt type of the highest
priority pending interrupt.
NOTE:
Reserved register bits are shown with gray shading. Reserved bits must be written
to a logic zero to ensure compatibility with future Intel products.
A1209-A0
15
0
V
T
0
V
T
2
V
T
3
V
T
4
I
R
E
Q
V
T
1
Содержание 80C186XL
Страница 1: ...80C186XL 80C188XL Microprocessor User s Manual...
Страница 2: ...80C186XL 80C188XL Microprocessor User s Manual 1995...
Страница 18: ...1 Introduction...
Страница 19: ......
Страница 27: ......
Страница 28: ...2 Overview of the 80C186 Family Architecture...
Страница 29: ......
Страница 79: ......
Страница 80: ...3 Bus Interface Unit...
Страница 81: ......
Страница 127: ......
Страница 128: ...4 Peripheral Control Block...
Страница 129: ......
Страница 137: ......
Страница 138: ...5 ClockGenerationand Power Management...
Страница 139: ......
Страница 154: ...6 Chip Select Unit...
Страница 155: ......
Страница 178: ...7 Refresh Control Unit...
Страница 179: ......
Страница 193: ......
Страница 194: ...8 Interrupt Control Unit...
Страница 195: ......
Страница 227: ......
Страница 228: ...9 Timer Counter Unit...
Страница 229: ......
Страница 253: ......
Страница 254: ...10 Direct Memory Access Unit...
Страница 255: ......
Страница 283: ......
Страница 284: ...11 Math Coprocessing...
Страница 285: ......
Страница 302: ...12 ONCE Mode...
Страница 303: ......
Страница 306: ...A 80C186 Instruction Set Additions and Extensions...
Страница 307: ......
Страница 318: ...B Input Synchronization...
Страница 319: ......
Страница 322: ...C Instruction Set Descriptions...
Страница 323: ......
Страница 371: ......
Страница 372: ...D Instruction Set Opcodes and Clock Cycles...
Страница 373: ......
Страница 396: ...Index...
Страница 397: ......