
208
Logical Device Configuration/Control Registers [0x30-0xFF]
Used to access the registers that are assigned to each logical unit. This chip supports six logical units
and has six sets of logical device registers. The six logical devices are Floppy, Parallel, Serial 1,
Serial 2, Keyboard Controller, and Runtime Registers. 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 61 – Logical Device Registers
LOGICAL DEVICE
REGISTER
Activate
ADDRESS
(0x30)
DESCRIPTION
STATE
C
Default = 0x00
on VCC POR and Hard
Reset
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
Reserved - Writes are ignored, reads return
0.
Vendor Defined - Reserved - Writes are
ignored, reads return 0.
Reserved - Writes are ignored, reads return
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 62 for the number of base
address registers used by each device.
Unused registers will ignore writes and return
zero when read.
0x70 is implemented for each logical device.
Refer to Interrupt Configuration Register
description. Only the keyboard controller
uses Interrupt Select register 0x72. Unused
register (0x72) will ignore writes and return
zero when read. Interrupts default to edge
high (ISA compatible).
Logical Device Control
(0x31-0x37)
C
Logical Device Control
(0x38-0x3f)
C
Memory Base Address
(0x40-0x5F)
C
I/O Base Address
Note 2
(see Device Base I/O
Address Table)
Default = 0x00
on VCC POR and Hard
Reset
Interrupt Select
(0x60-0x6F)
0x60,2,... =
addr[15:8]
0x61,3,... =
addr[7:0]
C
Defaults :
0x70 = 0x00,
on VCC POR and Hard
Reset
0x72 = 0x00,
on VCC POR and Hard
Reset
(0x70,0x72)
C