DIRECT MEMORY ACCESS UNIT

;NOW WE NEED TO SET THE PARAMETERS FOR THE CHANNEL AS FOLLOWS:

;

DESTINATION

SOURCE

;

-----------

------

;

I/O SPACE

MEMORY SPACE

;CONSTANT PTR INCREMENT PTR

;TERMINATE ON TC, INTERRUPT, SOURCE SYNCHRONIZE, INTERNAL REQUESTS,

;LOW PRIORITY RELATIVE TO CHANNEL 1, BYTE XFERS.

MOV AX, 0001011101010110B

MOV DX, D0CON

OUT DX, AX

;NOW WE ASSUME THAT TIMER 2 HAS BEEN PROPERLY PROGRAMMED FOR A 22uS DELAY.

;WHEN THE TIMER IS STARTED, A DMA TRANSFER WILL OCCUR EVERY 22uS.

CODE_SEG ENDS

DATA_SEG SEGMENT

WAVEFORM_DATADB 0,1,2,3,4,5,6,7,8,9,10,11,12,13

DB 14,15,16,17,18,19,20,21,22,23,24

;ETC., UP TO 255 DATA_SEG ENDS

END START

Example 10-2. Timed DMA Transfers (Continued)

10-27

Page 282
Image 282
Intel 80C188XL, 80C186XL user manual 10-27