141
Logical
Device
Configuration/Control
Registers [0x30-0xFF]
Used to access the registers that are assigned
to each logical unit. This chip supports nine
logical units and has nine sets of logical device
registers.
The six logical devices are Floppy,
Parallel, Serial 1, Serial 2, Keyboard Controller,
and Auxiliary_I/O.
A separate set (bank) of
control and configuration registers
exists for
each logical device and is selected with the
Logical Device # Register (0x07).
The INDEX PORT is used to select a specific
logical device register. These registers are then
accessed through the DATA PORT.
The Logical Device registers are accessible only
when the device is in the Configuration State.
The logical register addresses are shown in the
table below.
Table 55 - Logical Device Registers
LOGICAL DEVICE
REGISTER
ADDRESS
DESCRIPTION
STATE
Activate
Note1
Default = 0x00
on Vcc POR or
Reset_Drv
(0x30)
Bits[7:1] Reserved, set to zero.
Bit[0]
= 1
Activates the logical device currently
selected through the Logical Device
# register.
= 0
Logical device currently selected is
inactive
C
Logical Device Control
(0x31-0x37)
Reserved - Writes are ignored, reads return
0.
C
Logical Device Control
(0x38-0x3f)
Vendor Defined - Reserved - Writes are
ignored, reads return 0.
C
Memory Base Address
(0x40-0x5F)
Reserved - Writes are ignored, reads return
0.
C
I/O Base Address
(see Device Base I/O
Address Table)
Default = 0x00
on Vcc POR or
Reset_Drv
(0x60-0x6F)
0x60,2,... =
addr[15:8]
0x61,3,... =
addr[7:0]
Registers 0x60 and 0x61 set the base
address for the device.
If more than one
base address is required, the second base
address is set by registers 0x62 and 0x63.
Refer to Table 64 for the number of base
address registers used by each device.
Unused registers will ignore writes and return
zero when read.
C