Little Board™/486
e
Technical Manual
2–24
Parallel Port Interrupt Enable
Bit 4 in the control register (see Table 2–18) enables the parallel port interrupt. If this bit is high,
then a rising edge on the -ACK (IRQ) line produces an interrupt on the interrupt IRQ7 (or IRQ5 if
configured as the secondary port). .
Table 2–18. Parallel Port Register Bits
Register
Bit
Signal Name
or Function
In/Out
Active
High/Low
J15
Pin
DB25F
Pin
DATA
(378h)
0
1
2
3
4
5
6
7
Data 0
Data 1
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
High
High
High
High
High
High
High
High
3
5
7
9
11
13
15
17
2
3
4
5
6
7
8
9
STATUS
(379h)
0
1
2
3
4
5
6
7
0
0
0
-ERROR
SLCT
PE
-ACK (IRQ)
BUSY
In
---
---
In
In
In
In
In
---
---
---
Low
High
High
Low
High
---
---
---
4
25
23
19
21
---
---
---
15
13
12
10
11
CONTROL
(37Ah)
0
1
2
3
4
5
6
7
-STROBE
-AUTOFD
-INIT
SLC
IRQE
PCD
1
1
Out
Out
Out
Out
---
---
---
---
Low
Low
High
High
High
High
---
---
1
2
6
8
---
---
---
---
1
14
16
17
---
---
---
---
Summary of Contents for 486E P/N 5001561 Revision A
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