W83977AF Information Storage Devices, Inc, W83977AF Datasheet - Page 136

• Manufacturer Part Number: W83977AF
• Description: W83877TF Plus Kbc, Cir, RTC
• Manufacturer: Information Storage Devices, Inc

CRF1 (Default 0x00)
CRF2 (Default 0xFF)
CRF4 (Default 0x00)
FDD0 Selection:
Bit 7-6 : Boot Floppy
Bit 5 : Media ID1 Polarity
Bit 4 : Media ID0 Polarity
Bit 3-2 : Density Select
Bit 1 : DISFDDWR
Bit 0 : SWWP
Bit 7-6 : FDD D Drive Type
Bit 5-4 : FDD C Drive Type
Bit 3-2 : FDD B Drive Type
Bit 1:0 : FDD A Drive Type
When FDD is in enhanced 3-mode(CRF0.bit0=1),these bits determine SELDEN value in TABLE A
of CRF4 and CRF5 as follows.
Note: X means don't care.
Bit 7 : Reserved.
Bit 6 : Precomp. Disable.
Bit 5 : Reserved.
DTYPE1
= 00 FDD A
= 01 FDD B
= 10 FDD C
= 11 FDD D
= 0 Non-Inverse
= 1 Inverse
= 0 Non-Inverse
= 1 Inverse
= 00 Normal (Default)
= 01 Normal
= 10 1 ( Forced to logic 1)
= 11 0 ( Forced to logic 0)
= 0 Enable FDD write.
= 1 Disable FDD write(forces pins WE, WD to stay high).
= 0 Normal, use WP to determine whether the FDD is write protected or not.
= 1 FDD is always write-protected.
= 1
= 0
0
0
0
0
0
1
1
Disable FDC Precompensation.
Enable FDC Precompensation.
DPYTE0
0
0
0
0
1
0
1
DRATE1
X
X
1
0
0
1
0
- 124 -
DRATE0
X
X
1
0
1
0
1
W83977F/ W83977AF
SELDEN
Publication Release Date: March 1998
1
1
0
0
0
1
0
PRELIMINARY
Revision 0.58