82801DB Datasheet, PDF (388/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

IDE Controller Registers (D31:F1)
10.1.12
SCMD_BAR—Secondary Command Block Base Address
Register (IDE D31:F1)
Address Offset: 18h–1Bh
Default Value: 00000001h
Attribute: R/W
Size:
32 bits
Bit
31:16
15:3
2:1
0
Description
Reserved
Base Address — R/W. Base address of the I/O space (8 consecutive I/O locations).
Reserved
Resource Type Indicator (RTE) — RO. This bit is set to one, indicating a request for I/O space.
NOTE: This 4-byte I/O space is used in native mode for the Secondary controller’s Command Block.
10.1.13
SCNL_BAR—Secondary Control Block Base Address
Register (IDE D31:F1)
Address Offset: 1Ch–1Fh
Default Value: 00000001h
Attribute: R/W
Size:
32 bits
Bit
31:16
15:2
1
0
Description
Reserved
Base Address — R/W. Base address of the I/O space (4 consecutive I/O locations).
Reserved
Resource Type Indicator (RTE) — RO. This bit is set to one, indicating a request for I/O space.
NOTE: This 4-byte I/O space is used in native mode for the Secondary controller’s Command Block.
10.1.14
BM_BASE — Bus Master Base Address Register
(IDE—D31:F1)
Address Offset: 20h–23h
Default Value: 00000001h
Attribute: R/W
Size:
32 bits
The Bus Master IDE interface function uses Base Address register 5 to request a 16-byte I/O space
to provide a software interface to the Bus Master functions. Only 12 bytes are actually used
(6 bytes for primary, 6 bytes for secondary). Only bits [15:4] are used to decode the address.
Bit
31:16
15:4
3:1
0
Description
Reserved
Base Address — R/W. Base address of the I/O space (16 consecutive I/O locations).
Reserved
Resource Type Indicator (RTE) — RO. Hardwired to 1, indicating a request for I/O space.
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Intel^® 82801DB ICH4 Datasheet