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Technical Reference Guide 361834-002 5-3
Input/Output Interfaces
IDE Bus Master Control Registers
The IDE interface can perform PCI bus master operations using the registers listed in Table 5-2.
These registers occupy 16 bytes of variable I/O space set by software and indicated by PCI
configuration register 20h in the previous table.
NOTE:
Unspecified gaps are reserved, will return indeterminate data, and should not be written to.
IDE (PATA) Connector
These systems provide a standard 40-pin connector for a primary IDE device and in most factory
configurations connects to a optical drive (CD or DVD). Some signals are re-defined for
UATA/33 and higher modes. Device power is supplied through a separate connector.
Figure 5-1. 40-Pin IDE (PATA) Connector.
Table 5-2.
IDE Bus Master Control Registers
I/O
Address
Offset
Size
(Bytes) Register
Default
Value
00h 1 Bus Master IDE Command (Primary) 00h
02h 1 Bus Master IDE Status (Primary) 00h
04h 4 Bus Master IDE Descriptor Pointer (Pri.) 0000 0000h
08h 1 Bus Master IDE Command (Secondary) 00h
0Ah 2 Bus Master IDE Status (Secondary) 00h
0Ch 4 Bus Master IDE Descriptor Pointer (Sec.) 0000 0000h