These registers are not affected by soft resets.
TABLE 76 - FLOPPY DISK CONTROLLER, LOGICAL DEVICE 0 [LOGICAL DEVICE NUMBER = 0X00]
NAME
REG INDEX
DEFINITION
STATE
FDD Mode
Register
0xF0 R/W
Bit[0] Floppy Mode
C
= 0Normal Floppy Mode (default)
= 1 Enhanced Floppy Mode 2 (OS2)
Bit[1] FDC DMA Mode
Default = 0x0E
= 0 Burst Mode is enabled
= 1 Non-Burst Mode (default)
Bit[3:2] Interface Mode
on Vcc POR or
Reset_Drv
= 11 AT Mode (default)
= 10 (Reserved)
= 01 PS/2
= 00 Model 30
Bit[4] Swap Drives 0,1 Mode
= 0 No swap (default)
= 1 Drive and Motor sel 0 and 1 are swapped.
Bits[5] Reserved, set to zero.
Bit [6] Output Type Control:
0= FDC outputs are OD24 open drain (default)
1= FDC outputs are O24 push-pull.
Bit [7] FDC output Control:
0= FDC outputs active (default)
1= FDC outputs tristated
Note: these bits do not affect the parallel port FDC pins.
FDD Option
Register
0xF1 R/W
Bits[1:0] Reserved, set to zero
Bits[3:2] Density Select
C
= 00 Normal (default)
Default = 0x00
= 01 Normal (reserved for users)
= 10 1 (forced to logic "1")
= 11 0 (forced to logic "0")
Bit[5:4] Reserved, set to zero
Bits[7:6] Boot Floppy
on Vcc POR or
Reset_Drv
= 00 FDD 0 (default)
= 01 FDD 1
= 10 Reserved (neither drive A or B is a boot drive).
= 11 Reserved (neither drive A or B is a boot drive).
FDD Type
Register
0xF2 R/W
Bits[1:0] Floppy Drive A Type
Bits[3:2] Floppy Drive B Type
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)
C
C
Default = 0xFF
on Vcc POR or
Reset_Drv
Note: The FDC37B78x supports two floppy drives
0xF3 R
Reserved, Read as 0 (read only)
186
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