Table 59 - Floppy Disk Controller, Logical Device 0 [Logical Device Number = 0x00]
NAME
REG INDEX
DEFINITION
Bit[0] Forced Write Protect 0
= 0 Inactive (default)
STATE
FDD Option
Register
0xF1 R/W
C
= 1 FDD nWRTPRT input is forced active when
the drive has been selected.
Bit[1] Reserved
Default = 0x00
on Vcc POR or
Reset_Drv
Bits[3:2] Density Select
= 00
= 01
= 10
= 11
Normal (default)
Normal (reserved for users)
1 (forced to logic "1")
0 (forced to logic "0")
Bit[7:4] Reserved.
nWRTPRT (to the FDC Core) = (nDS0 AND FORCE
WRTPRT) OR nWRTPRT (from the FDD Interface)
Note: Boot floppy is always drive 0.
Note: the Force Write Protect 0 bit also applies to the
Parallel Port FDC.
FDD Type Register
Default = 0xFF
0xF2 R/W Bits[1:0] Floppy Drive A Type
Bits[3:2] Floppy Drive B Type
C
Bits[5:4] Reserved (could be used to store Floppy
Drive C type)
Bits[7:6] Reserved (could be used to store Floppy
Drive D type)
on Vcc POR or
Reset_Drv
Note: The FDC37B77x supports two floppy drives
0xF3 R
Reserved, Read as 0 (read only)
C
C
FDD0
0xF4 R/W Bits[1:0] Drive Type Select: DT1, DT0
Bits[2] Read as 0 (read only)
Default = 0x00
Bits[4:3] Data Rate Table Select: DRT1, DRT0
Bits[5] Read as 0 (read only)
Bits[6] Precompensation Disable PTS
=0 Use Precompensation
on Vcc POR or
Reset_Drv
=1 No Precompensation
Bits[7] Read as 0 (read only)
FDD1
0xF5 R/W Refer to definition and default for 0xF4
C
148
SMSC [ SMSC CORPORATION ]
