w83877atd Winbond Electronics Corp America, w83877atd Datasheet - Page 133

• Manufacturer Part Number: w83877atd
• Description: Winbond I/o
• Manufacturer: Winbond Electronics Corp America

8.2.31 Configuration Register 27 (CR27)
When the device is in Extended Function mode and EFIR is 27, the CR27 register can be accessed
through EFDR. Default = 05H if CR6 bit 2 = 1; default = 00H if CR16 bit 2 = 0. The bit definitions are
as follows:
ECPIRQx2-ECPIRQx0 (Bit7-bit 5): These bits are configurable equivalents to bit[5:3] of cnfgB
register in ECP
assigned for the ECP printer port. It is the software designer's responsibility to ensure that CR27[7:5]
and CR27[3:0] are consistent. For example, CR27[7:5] should be filled with 001 (select IRQ 7) if
CR27[3:0] are to be programmed as 0101 (select IRQ_E) while IRQ_E is connected to IRQ 7.
Bit 4: Reserved.
PRTIQS3-PRTIQS0 (Bit 3-bit 0): Select IRQ resource for the parallel port. Any unselected IRQ pin is
in tri-state.
CR27[7:5]
CR27[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
000
001
010
011
100
101
110
111
mode,
reflect other IRQ resources selected by CR27[3:0] (default)
IRQ 7
IRQ 9
IRQ 10
IRQ 11
IRQ 14
IRQ 15
IRQ 5
except that cnfgB[5:3] are read-only bits. They indicate the IRQ resource
7
6
select IRQ pin
IRQ_G
IRQ_A
IRQ_B
IRQ_C
IRQ_D
IRQ_E
IRQ_H
IRQ_F
None
5
4
IRQ resource
3
- 129 -
2
1
0
ECPIRQx0
ECPIRQx1
ECPIRQx2
PRTIQS0
PRTIQS1
PRTIQS2
PRTIQS3
reserved
Publication Release Date: April 1998
W83877ATF
Version 0.51