W83977A Winbond Electronics Corp America, W83977A Datasheet - Page 111

• Manufacturer Part Number: W83977A
• Description: Winbond I/O
• Manufacturer: Winbond Electronics Corp America

CRF1 (Default 0x00)
CRF2 (Default 0xFF)
Bit 0: Floppy Mode
Bit 7 - 6: Boot Floppy
Bit 5, 4: Media ID1, Media ID0. These bits will be reflected on FDC's Tape Drive Register bit 7, 6.
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.
DTYPE1
= 0 Normal Floppy Mode (Default)
= 1 Enhanced 3-mode FDD
= 00 FDD A
= 01 FDD B
= 10 FDD C
= 11 FDD D
= 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 stay high).
= 0 Normal, use WP to determine whether the FDD is write protected or not.
= 1 FDD is always write-protected.
0
0
0
0
0
1
1
DPYTE0
0
0
0
0
1
0
1
DRATE1
X
X
1
0
0
1
0
-101 -
DRATE0
X
X
1
0
1
0
1
SELDEN
Publication Release Date: March 1998
1
1
0
0
0
1
0
W83977TF
PRELIMINARY
Revision 0.62