Compaq W4000 manual IDE Configuration Registers, IDE Bus Master Control Registers

Chapter 5 Input/Output Interfaces

Hard drives types not found in the ROM’s parameter table are automatically configured as to (soft)type by DOS as follows:

Primary controller: drive 0, type 65; drive 1, type 66

Secondary controller: drive 0, type 68; drive 1, type 15

Non-DOS (non-Windows) operating systems may require using Setup (F10) for drive configuration.

5.2.1.1 IDE Configuration Registers

The IDE controller is configured as a PCI device with bus mastering capability. The PCI configuration registers for the IDE controller function (PCI device #31, function #1) are listed in Table 5-1.

Table 5–1. IDE PCI Configuration Registers

Table 5-1.

EIDE PCI Configuration Registers (82801, Device 31/Function 1)

PCI Conf.		Reset	PCI Conf.		Reset
Addr.	Register	Value	Addr.	Register	Value
00-01h	Vender ID	8086h	0F..1Fh	Reserved	0’s
02-03h	Device ID	244Bh	20-23h	BMIDE Base Address	1
04-05h	PCI Command	0000h	2C, 2Dh	Subsystem Vender ID	0000h
06-07h	PCI Status	0280h	2E, 2Fh	Subsystem ID	0000h
08h	Revision ID	00h	30..3Fh	Reserved	0’s
09h	Programming	80h	40-43h	Pri./Sec. IDE Timing	0’s
0Ah	Sub-Class	01h	44h	Slave IDE Timing	00h
0Bh	Base Class Code	01h	48h	Sync. DMA Control	00h
0Dh	Master Latency Timer	00h	4A-4Bh	Sync. DMA Timing	0000h
0Eh	Header Type	00h	54h	EIDE I/O Config.Register	00h

NOTE:

Assume unmarked gaps are reserved and/or not used.

5.2.1.2 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.

Table 5–2.IDE Bus Master Control Registers

Table 5-2.

IDE Bus Master Control Registers

I/O Addr.	Size		Default
Offset	(Bytes)	Register	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

NOTE:

Unspecified gaps are reserved, will return indeterminate data, and should not be written to.

5-2Compaq Evo and Workstation Personal Computers

Featuring the Intel Pentium 4 Processor

Second Edition – January 2003