8255A7.17.2 8255A7.3 8255A07.4 8255A17.5 8255A2

*CPU,

81632 ()

7.1

*I/O: A/DD/AIEEE-488816/816

CPUIntel8255APPIZilogZ-80PIOMC6820PIO7.2 8255A8255A1.8255A8AB4C/4I/OCPUI/O

PC12PCCPU8255APC12I/O8255A8255

2.8255A 8255A+5V401 D0D7CPU8255A8255ACPU8255ACPU

8255A RDWRRESET8255AABC24

PA0PA7A/ PB0PB7B/ PC0PC7C/ 24I/OAB/I/OBusyA/DEOCAB8255A8255A

C8255AC a. b. c. d.

28255A4

88255ACPU //RDWRCSA1A0 /ABC8255A38port ABABC

7.1 8255A

CS A1A0RDWRPC00001PA CPU60H200H00101PB CPU61H201H01001PC CPU62H202H00010PA CPU60H200H00110PB CPU61H201H01010PC CPU62H202H0111063H203H10110110163H203H

8255A1.8255A3PAPBPC8110

1 A1CB0C10110001BB1H 8255A8255A8255A

MOV DX203H 8255A MOV AL0B1H OUT DXAL

2./PC8010.

2CPC200000101B05H 8255APCPC2 MOV DX203H 8255A MOV AL05H PC2=1 OUT DXAL PC2 MOV DX203H 8255A MOV AL04H PC2=0 OUT DXAL

C38255APC7 MOV DX203H 8255A MOV AL00001110B PC7=0 OUT DXAL NOP NOP MOV AL00001111B PC7=1 OUT DXAL

3. 8255A38255A /PC3 D7 /

4.AB AB/CAB100

4PA7/PA7. MOV DX200H PA IN ALDX A MOV AHAL OR AL80H PA7=1 OUT DXAL PA7 MOV ALAH OUT DXAL

PA7MOV DX200H AIN ALDX MOV AHAL AND AL7FH PA7=0OUT DXAL PA7 MOV ALAH OUT DXAL

8255A 8255APA012PBPC01)

*7.3 8255A00/ I/O08416

0C 12I/OPAPBPC

1. CPUBUF256ASCII

2.

:CPU BUSYBUSY=1BUSY=0 DATA BIT1DATA BIT8 DATA STROBE- 1 11BUSY=1 10ACK-

3. 8DATABIT18

1STB1BUSY18255APA80

CODE SEGMENTASSUME CSCODEDSCODEORG100HSTART MOV AXCODE MOV CSAX MOV DSAX MOV DX203H 8255A MOV AL10000001B OUT DXAL A0 C4C7 C0C3

MOV AL00001111B PC7STB--=1OUT DXALMOV SI, OFFSET BUF MOV CXOFFH MOV DX202H PCIN ALDX BUSY=0PC2=0AND AL04H ;00000100B JNZ L AMOV DX200H PAMOV AL[SI] OUT DXAL AMOV AL203H 8255AMOV AL00001110B STB-PC7=0L:

OUT DXALNOP NOPMOV AL00001111B STB-PC7=1OUT DXALINC SI 1DEC CX 1JNZ L MOV AX4C00H INT 21H BUF DB 256ASCIICODE ENDSEND START

7.4 8255A1

1/I/OCPU PAPBPCC

/PC111 I/O8255AI/O8255ACPU8255AABC38255ACPU STB8255A

1IBF8255AINTR8255ACPU

21 17.3

STB8255A STB300ns8255AIBF8255A 7.3 1

8255AMINMAXtSTSTB500nstSTBSTB=0IBF=1300nstSITSTB=1INTR=1300ns tRIBRD=1IBF=0300nstRITRD=0INTR=0400nsTPSSTB0nstPH180ns

STB300nsINTE=1IBFINTRCPUCPU CPUINTRRDINTR 1I/O8255ACPU4CPU8255AI/O STB INTR IBF RD

2. 11

211 1

CPU8255ACPU8255AWROBF8255AWRINTROBFACK8255AACKOBFOBFINTE=1ACKINTRCPUOUT8255A

1CPU8255AI/O41 18255AIBFOBF8255A8255ACPU

2.

8ABA5B33.8255A/CCCC CPU------IBFINTR------OBFINTRINTE8255AI/O/

PAINTEA=1PC4=1INTEA=0PC4=0 MOV DX203H 8255A MOV AL00001001B PC4=1 OUT DXAL MOV AL00001000B PC4=0 OUT DXAL1 . 1K 8255A18255A0CPU

2. 8255A8255A8255AI/O3.1 2

MOV DX203H 8255AMOV AL10100000B OUT DXAL MOV AL00001101B INTEA=1OUT DXAL PC6=1MOV SIOFFSET BUFS MOV CX3FFH MOV DX200H A ; OBF-MOV AL[SI] ACK-OUT DX AL

INC SI 1 DEC CX 1L MOV DX202H 8255A IN AL DX INTRA=1 AND AL08H PC3=1 JZ L A MOV DX200H 8255APA MOV AL[SI] OUT DXAL A INC SI 1

DEC CX 1 JNZ L MOV AH4CH INT 21H BUFS DB 1024

*7.5 8255A2PA//PA2CPU1

21. 2A/C5PC3~PC78255AA2

2. 2

2 211. 2568255A28255A03.1 8255APA8259AIR28255APAPB2

*

*2003 12.5 21:00*2003 12.9