W83877 Winbond Electronics Corp America, W83877 Datasheet - Page 73

• Manufacturer Part Number: W83877
• Description: Winbond I/O
• Manufacturer: Winbond Electronics Corp America

8.2.3 Configuration Register 2 (CR2), default = 00H
When the device is in Extended Function mode and EFIR is 02H, the CR2 register can be accessed
through EFDR. The bit definitions are as follows:
When the W83877F is programmed into extension adapter mode, the contents of this register are a
base address for the extension adapter. When base addresses EA3-EA9 are written into CR2, both
the
port can latch the same base address through pins XD1-XD7. After the base address is latched into
CR2, a subsequent read/write cycle to this same base address will generate an XRD or XWR signal.
If CEA is set to 0, then the W83877F will compare system addresses SA9-SA3 with EA9-EA3 to
generate a compare-equal signal for this read/write command to access the Extension adapter. If
CEA is set to 1, then only EA9-EA4 are used in this comparison.
XRD
0
1
and XWR pins will be active low simultaneously and an adapter connected to the parallel
Drives A and B assigned as usual
Drive A and drive B assignments exchanged
7
6
5
4
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3
2
1
0
Publication Release Date: January 1996
CEA
EA3
EA4
EA5
EA6
EA7
EA8
EA9
W83877F
Revision A2