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10-25
DIRECT MEMORY ACCESS UNIT
Example 10-1. Initializing the DMA Unit (Continued)
MOV AX, 512 ; THE DISK READS IN 512 BYTE
SECTORS
MOV DX, D1TC ; XFER COUNT REG
OUT DX, AX
; NOW WE NEED TO SET THE PARAMETERS FOR THE CHANNEL AS FOLLOWS:
;
; DESTINATION SOURCE
; ----------- ------
; MEMORY SPACE I/O SPACE
; INCREMENT PTR CONSTANT PTR
;
; TERMINATE ON TC, INTERRUPT, SOURCE SYNC, HIGH PRIORITY RELATIVE TO
; CHANNEL 0, BYTE XFERS, USE DRQ PIN FOR REQUEST SOURCE. ARM CHANNEL.
MOV AX, 1010001101100110B
MOV DX, D0CON
OUT DX, AX
; REQUESTS ON DRQ1 WILL NOW RESULT IN TRANSFERS
CODE_SEG ENDS
DATA_SEG SEGMENT
SOURCE_DATA_1DB '80C186EC INTEGRATED PROCESSOR'
DEST_DATA_1DB 30 DUP('MITCH') ; JUNK DATA FOR TEST
DISK_BUFF DB 512 DUP(?)
DATA_SEG ENDS
END START