SC1100 Datasheet, PDF (230/348 Pages) National Semiconductor (TI) – Geode™ Information Appliance On a Chip

Core Logic Module (Continued)
Table 5-36. F2BAR4+I/O Offset: IDE Controller Configuration Registers (Continued)
Bit Description
Offset 08h
IDE Bus Master 1 Command Register — Secondary (R/W)
Reset Value: 00h
7:4 Reserved. Must be set to 0. Must return 0 on reads.
3
Read or Write Control. Sets the direction of bus master transfers.
0: PCI reads are performed.
1: PCI writes are performed.
This bit should not be changed when the bus master is active.
2:1 Reserved. Must be set to 0. Must return 0 on reads.
0
Bus Master Control. Controls the state of the bus master.
0: Disable master.
1: Enable master.
Bus master operations can be halted by setting this bit to 0. Once an operation has been halted, it cannot be resumed. If this
bit is set to 0 while a bus master operation is active, the command is aborted and the data transferred from the drive is dis-
carded. This bit should be reset after completion of data transfer.
Offset 09h
Not Used
Offset 0Ah
IDE Bus Master 1 Status Register — Secondary (R/W)
7
Reserved. (Read Only)
6
Drive 1 DMA Capable. Allow Drive 1 to perform DMA transfers.
0: Disable.
1: Enable.
5
Drive 0 DMA Capable. Allow Drive 0 to perform DMA transfers.
0: Disable.
1: Enable.
4:3 Reserved. Must be set to 0. Must return 0 on reads.
2
Bus Master Interrupt. Indicates if the bus master detected an interrupt.
0: No.
1: Yes. Write 1 to clear.
1
Bus Master Error. Indicates if the bus master detected an error during data transfer.
0: No.
1: Yes. Write 1 to clear.
0
Bus Master Active. Indicates if the bus master is active.
0: No.
1: Yes.
Offset 0Bh
Not Used
Reset Value: 00h
Offset 0Ch-0Fh
IDE Bus Master 1 PRD Table Address — Secondary (R/W)
Reset Value: 00000000h
31:2 Pointer to the Physical Region Descriptor Table. This bit field contains a PRD table pointer for IDE Bus Master 1.
When written, this field points to the first entry in a PRD table. Once IDE Bus Master 1 is enabled (Command Register bit 0
= 1), it loads the pointer and updates this field (by adding 08h) so that it points to the next PRD.
When read, this register points to the next PRD.
1:0 Reserved. Must be set to 0.
www.national.com
230
Revision 1.1