第一节 并行接口的基本概念 一、并行通信和串行通信 二、并行接口概述...
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Transcript of 第一节 并行接口的基本概念 一、并行通信和串行通信 二、并行接口概述...
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12CPU/ /348255A58255A68255AAB1C C78255AAB1INTE INTE 8 8255AAB1
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8255A
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:
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, 0 1 1 0 1 0 1 0
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12CPU345
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=> =1=1 CPUCPU CPU CPU
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CPU =1CPU CPU =1 CPU
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: :
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:,CPU 80X868255A Z80Z80-PIO 6800MC6820PIA
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8255A8255A8255A8255A8255A
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8255AIntel840
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1. ABC 8
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A 3 ( 0 1 2) 8 PA7 ~ PA0
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B 2 0 1 8 PB7 ~ PB0
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A 1 2 B 1 C CPU C 0
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CS RD WR
0 0 1
D7~D0
0 1 0
D7~D0
1
1 1
0 0
,
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A1 A0
0 0
A
0 1
B
1 0
C
1 1
D
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8255ADABC 8255A
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ABC 8255A Port_Ctrl, 8255ACtrlData MOV DXPort_Ctrl ;DX MOV ALCtrlData ;AL OUT DX, AL ;
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1. ABC 0 1 2
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A F0 H B F1 H C F2 H D F3 H1)
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2) 1001 0001B91H : A0PC7~PC4 B0PC3~PC0
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MOV DX, 0F3H ;MOV AL, 91H ;OUT DX, AL MOV AL, 91H ; OUT 0F3H, AL
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2. C/ C10 AB C8255A
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PC2 0 PC4 1 MOV DX0F3H ;DX MOV AL0000 0100B ;PC20 OUT DX, AL MOV AL0000 1001B ;PC41 OUT DX, AL
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8255A1. 2. 0 3. 14. 2
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8255A: AB CACB 1.
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ACBC , 0 1 2 0: C 1: C3
2: C5
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1. 0
A 0 AC B 0 BC
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0 CPU 0 CPU
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0
0IN ALPORT
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0 IN ALPORT
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0
CPU (IN AL,PORT)8255A
I/O8088CPU8255A CPU
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0
0OUT PORTAL 88IO/MWR&CE
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0 OUT PORT AL I/O8088CPU8255A CPU
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2. 1 B1 C3B
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1
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1 CAB C C/ /
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1 CPU
AB C
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1PA7~PA0PC4PC5PC3INTEAPC4IBFARDD7~D0A1PB7~PB0PC2PC1PC0INTEBPC2RDB1D7~D0IBFBSTBBINTRB
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PA7~PA0PB7~PB0 STB: (1) (2) IBF (3) INTE=1, STBINTR CPU RD: (1) RD INTR (2) RD IBF (3) CPU
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1
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11
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CPU CPUWR (1) 8255A (2) OBF , (3)INTR ACK (1) ACKOBF (2) INTE=1, ACKINTR CPUD7~D0INTR
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32 2C5 8255A A 2
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0 1 2 A 2 C3 B1B0 /