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IRQ`S,I/O`S,DMA`S

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
IRQ 2 =       LINK / BRIDGE
IRQ 3=  DEFAULT COM  2       I/O=      02F8 02FF
               DEFAULT COM  4       I/O=      02E8 02EF
IRQ 4=  DEFAULT COM  1       I/O=      03F8 03FF
               DEFAULT COM  3       I/O=      03E8 03EF
IRQ 5=            LPT   2                  I/O=      0278 027F
IRQ 6=  FLOPPY DRIVE           I/O=      03F0 03F7
IRQ 7=           LPT 1                     I/0=       0378 037F
IRQ 8=      CMOS TIMER          I/0=    0070 - 0071
IRQ 9=      LINK/BRIDGE
IRQ 10=         OPEN               
IRQ 11=         OPEN
IRQ 12=       MOUSE                  I/O=         0238
IRQ 13=      MATH                     I/O=     00F0 00FF
              COPROCESSOR
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

DMA 0  =                    DRAM REFRESH
DMA 1  =                    SOUND CARD
DMA 2  =                 FLOPPY DISK DRIVE
DMA 3 =           ECP OR EPP PARALLEL PORT
DMA 4 =                  DMA CONTROLLER
DMA 5 =                    SOUND CARD
DMA 6 =                     AVAILABLE
DMA 7=    ISA IDE HARD DRIVE CONTROLLER

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irq,i/o,dma

CROY WORLD PRODUCTIONS