Table 63 - KYBD, Logical Device 7 [Logical Device Number = 0x07]
NAME
REG INDEX
0xF0
DEFINITION
KRESET and GateA20 Select
STATE
KRST_GA20
R/W
Bit[7] Polarity Select for P12
= 0 P12 active low (default)
= 1 P12 active high
Bits[6:3] Reserved
Default = 0x00
on Vcc POR or
Reset_Drv
Bit[2] Port 92 Select
= 0 Port 92 Disabled
= 1 Port 92 Enabled
Bit[1] Reserved
Bit[0] Reserved
0xF1 -
0xFF
Reserved - read as ‘0’
Table 64 - Auxilliary I/O, Logical Device 8 [Logical Device Number = 0x08]
NAME
REG
INDEX
DEFINITION
STATE
Default = 0x00
on VTR POR
Pin Multiplex
Controls
0xB8 R/W
Bits[7:0] Reserved
C
0xC0
Bit[0] IR Mode Select
Bit[1] DMA 3 Select
Bit[2] Reserved, read as “1”
Bit[3] 8042 Select
Default = 0x06 on
Vcc POR
Bit[4] Reserved
Bit[5:7] Reserved
Force Disk Change
0xC1
(R/W)
Bit[0] Force Change 0
Bit[1] Force Change 1
Bit[7:2] Reserved
C,R
Default = 0x03 on
Vcc POR
Force Change[1:0] can be written to 1 but are not
clearable by software.
Force Change 1 is cleared on nSTEP and nDS1
Force Change 0 is cleared on nSTEP and nDS0
DSKCHG (FDC DIR Register, Bit 7) = (nDS0 AND
Force Change 0) OR (nDS1 AND Force Change 1)
OR nDSKCHG
142
SMSC [ SMSC CORPORATION ]
