W83877 Winbond Electronics Corp America, W83877 Datasheet - Page 81

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

When the device is in Extended Function mode and EFIR is 09H, the CR9 register can be accessed
through EFDR. The bit definitions are as follows:
PRTMODS2 (Bit 7):
This bit and PRTMODS1, PRTMODS0 (bits 3, 2 of CR0) select the operating mode of the W83877.
Refer to the descriptions of CR0.
LOCKREG (Bit 6):
This bit enables or disables the reading and writing of all configuration registers.
EN3MODE (Bit 5):
This bit enables or disables three mode FDD selection. When this bit is high, it enables the read/write
3F3H register.
When three mode FDD function is enabled, the value of RWC depends on bit 5 and bit 4 of
TDR(3F3H). The values of RWC and their meaning are shown in Table 7-4.
Table 7-4
Bit 4: Reserved.
CHIP ID 3, CHIP ID 2, CHIP ID 1, CHIP ID 0 (Bit 3-0):
These four bits are read-only bits that contain chip identification information. The value is 0AH for
W83877F during a read.
BIT 5 OF TDR
0
1
0
1
0
0
1
1
Enables the reading and writing of CR0-CR29
Disables the reading and writing of CR0-CR29 (locks W83877F extension functions)
Disables 3 mode FDD selection
Enables 3 mode FDD selection
BIT 4 OF TDR
0
1
0
1
7
6
5
4
3
Normal
RWC
- 81 -
X
0
1
2
1
0
1.2 M FDD
EN3MODE
CHIP ID0
CHIP ID1
CHIP ID2
CHIP ID3
Reserved
LOCKREG
PRTMODS2
RWC = 0
250K bps
Publication Release Date: January 1996
X
X
500K bps
RWC = 1
1.4M FDD
W83877F
X
X
Revision A2