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 80C186EA
Страница 1: ...80C186EA 80C188EA Microprocessor User s Manual...
Страница 2: ...80C186EA 80C188EA Microprocessor User s Manual 1995...
Страница 19: ......
Страница 20: ...1 Introduction...
Страница 21: ......
Страница 28: ...2 Overview of the 80C186 Family Architecture...
Страница 29: ......
Страница 79: ......
Страница 80: ...3 Bus Interface Unit...
Страница 81: ......
Страница 129: ......
Страница 130: ...4 Peripheral Control Block...
Страница 131: ......
Страница 139: ......
Страница 140: ...5 ClockGenerationand Power Management...
Страница 141: ......
Страница 165: ......
Страница 166: ...6 Chip Select Unit...
Страница 167: ......
Страница 190: ...7 Refresh Control Unit...
Страница 191: ......
Страница 205: ......
Страница 206: ...8 Interrupt Control Unit...
Страница 207: ......
Страница 239: ...INTERRUPT CONTROL UNIT 8 32...
Страница 240: ...9 Timer Counter Unit...
Страница 241: ......
Страница 265: ......
Страница 266: ...10 Direct Memory Access Unit...
Страница 267: ......
Страница 295: ...DIRECT MEMORY ACCESS UNIT 10 28...
Страница 296: ...11 Math Coprocessing...
Страница 297: ......
Страница 314: ...12 ONCE Mode...
Страница 315: ......
Страница 318: ...A 80C186 Instruction Set Additions and Extensions...
Страница 319: ......
Страница 330: ...B Input Synchronization...
Страница 331: ......
Страница 334: ...C Instruction Set Descriptions...
Страница 335: ......
Страница 383: ...INSTRUCTION SET DESCRIPTIONS C 48...
Страница 384: ...D Instruction Set Opcodes and Clock Cycles...
Страница 385: ......
Страница 408: ...Index...
Страница 409: ......