D7-DO .
, , . 9.14. 1 = 1 (. . C/D = 1, RD = 1 WR = 0) . . 9.15. , . , = 1, . 0, . ( = 1) ( = 0).
, , RxC . . \ RxC
= X .
. 9.14. .
10 300 1200, 4800 , RxC - 19,2
2 3 , 4 , 5 - ( ). . 6 , SYNDET- , 7
. 9.15. : () ()
SYNDET , , () . , SYNDET . , . , .
. 9.16. 0 1 , 2 1 . 1 1, DTR 0, DTR CD . 1 3 TxD = 0, .
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. 9.16.
. , 1
1 4 . 5 " " (RTS) . RTS , 1 5 . 6 1 8251 (. . . 9.14 ). 7 ; 1 8251 ()
. 9.17 . , . , () , 8251 SYNDET. , () 8251, SYNDET, RS-232-C , - TxD RxD ( . 9.10)
, : 7 , 2 .
MOV AL,11111010B
OUT 51H,AL
MOV AL,00110011B
OUT 51H,AL
, 51, 16 .
8251 :
MOV AL,00111000B
OUT 51H,AL
MOV A1_,16H
OUT 51H,AL
MOV AL,10010100B
OUT 51H,AL 338
-
)
. 9.17. 8251 () () .
, 7 , , , .
. 9.18. 1, 2 6 RxRDY, TxE SYNDET. TxRDY ,
. 9.18.
. TxRDY CTS TxEN. RxRDY , . TxRDY RxRDY -, - . TxRDY , , RxRDY - . 2 , . , , . 3, 4 5 , . , 1. DSR , 7 - 1, .
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. 9.19 , - 80 8251 ( 0050) , LINE. RxRDY , , .
. 9.19. 8251
, , , .
RxRDY, , , RxRDY = 1. 8 , 0. , . 8 , .