IRQ, INTERRUPT REQUEST
A COMPUTER INSTRUCTION THAT MOMENTARILY STOPS THE NORMAL OPERATION OF A ROUTINE.THE OPERATION CAN USUALLY BE RESUMED LATER
FROM THE INTERRUPTION POINT.AS THE PERIPHERAL DEVICES INTERFACE WITH THE CENTRAL PROCESSING UNIT( CPU ),THEY FREQUENTLY SEND
SIGNALS TO INDICATE THAT A SOFTWARE ROUTINE OR CIRCUIT NEEDS ATTENTION FROM THE CPU.
I/O ADDRESS
COMMUNICATION WITH DEVICES IS DONE BY ASSIGNING THEM UNIQUE I/O ADDRESS,WHICH ARE PATTERNS OF ONES AND ZEROS TRANSMITTED
ACROSS THE ADDRESS BUS BY THE CPU TO ADDRESS MEMORY.ALL OF THE DIFFERENT PATTERNS USED BY THE CPU TO TALK TO THE
DEVICES INSIDE YOUR COMPUTER ARE KNOWN AS THE I/O ADDRESS.ALL DEVICES, BOTH THOSE EMBEDDED ON THE MOTHERBOARD AND THOSE INSERTED
INTO EXPANSION SLOTS,RESPOND TO SPECIAL UNIQUE PATTERNS BUILT INTO THEM.
IRQ 0
IRQ
0 = SYSTEM TIMER
I/O =
040 - 043 |
IRQ 1=
KEYBOARD
I/O=
060 - 063 |
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IRQ
3=
DEFAULT COM
2 I/O= 02F8 02FF
DEFAULT COM
4 I/O= 02E8 02EF
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IRQ
4=
DEFAULT COM
1 I/O= 03F8 03FF
DEFAULT COM
3 I/O= 03E8 03EF
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IRQ
5=
LPT 2
I/O=
0278 027F |
IRQ 6= FLOPPY DRIVE I/O= 03F0 03F7
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IRQ
7=
LPT 1
I/0=
0378 037F |
IRQ 8= CMOS
TIMER
I/0= 0070
- 0071 | |
IRQ 10=
OPEN
|
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IRQ 13=
MATH
I/O= 00F0 00FF
COPROCESSOR
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IRQ 14=
PRIMARY IDE
I/O=
01F0 01FF |
IRQ
15=
SECONDARY IDE
I/O=
0170 - 0177 |
DMA ,DIRECT MEMORY ACCESS
ALLOWS A DEVICE TO BYPASS THE PROCESSOR TO DIRECTLY ACCESS MEMORY.DEVICES WITH A DMA CHANNEL ASSIGNMENT GAIN THE ADVANTAGES
OF FASTER DATA TRANSFERS THAT DO NOT HAVE TO PASS THROUGH THE CPU.NOT EVERY DEVICE
DMA 0
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DMA
2 =
FLOPPY DISK DRIVE |
DMA
3 =
ECP OR EPP PARALLEL PORT |
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DMA 7= ISA IDE HARD DRIVE CONTROLLER
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