8259A
/ 8259A. , ,
, 8086. , ,
8259A.
,
8259A ().
20h 21h / ( 8-6). 21h
. (..
) , ,
IRQ ( ,
IRQ0), .
20h
8259A. , MS-DOS 20h .
CPU
20h
EOI=20h
20h
8259A IRQ
1=a.
0 0 0 0 3. 4. 5. 6. 0=b.
COM2:
COM1:
.8-6. 8259A
a. - ; b. - ;
|
MS-DOS (COM1)
IRQ4 ( 12),
(COM2) IRQ3 ( 11). ,
COM3 COM4 , ,
IRQ, ( COM1 COM2
IRQ). , 8259A
COM1 21h
, EFh. COM1
, 10h, . , 8259A
COM1
IN AL,21H ;
AND AL,EFH ; IRQ4
OUT 21H,AL ;
|
COM1 , 8259A
IN AL,21H ;
OR AL,10H ; IRQ4
OUT 21H,AL ;
|
,
, ,
.
,
8259A
. ,
20h 20h / :
MOV AL,20H ;
OUT 20H,AL ; 20 8259A
|
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