Intel 8253 - Page 646

12
MODE 2 AND MODE 0 (INPUT) MODE 2 AND MODE 0 (OUTPUT)
MODE 2 AND MODE 1 (OUTPUT) MODE 2 AND MODE 1 (INPUT)
FIGURE 14. MODE 2 COMBINATIONS
1
D7
1
D6
D5 D4 D3 D2 D1 D0
CONTROL WORD
PC7
8
STBA
PA7-PA0
OBFA
IBFA
PC5
PC2-PC0
3
RD
PC2-PC0
1 = INPUT
0 = OUTPUT
ACKA
PC6
INTRA
PC3
I/O
PC4
PB7-PB0
01
1/0
8
WR
1
D7
1
D6
D5 D4 D3 D2 D1 D0
CONTROL WORD
PC7
8
STBA
PA7-PA0
OBFA
IBFA
PC5
PC2-PC0
3
RD
PC2-PC0
1 = INPUT
0 = OUTPUT
ACKA
PC6
INTRA
PC3
I/O
PC4
PB7, PB0
00
1/0
8
WR
1
D7
1
D6
D5 D4 D3 D2 D1 D0
CONTROL WORD
PC7
8
STBA
PA7-PA0
OBFA
IBFA
PC5
RD
ACKA
PC6
INTRA
PC3
PC4
PB7-PB0
10
8
WR
PC1
OBFB
ACKB
PC2
PC0
INTRB
1
D7
1
D6
D5 D4 D3 D2 D1 D0
CONTROL WORD
PC7
8
STBA
PA7-PA0
OBFA
IBFA
PC5
RD
ACKA
PC6
INTRA
PC3
PC4
PB7-PB0
11
8
WR
PC2
STBB
PC1
PC0
INTRB
IBFB
82C55A