IFB Usage Considerations

10.5.7.1BMIS1 - Bus Master IDE Status Register 1(Primary: Bus Master IDE Base I/O Address + Offset 02h)10.5.7.2BMIS2 - Bus Master IDE Status Register 2(Secondary: Bus Master IDE Base I/O Address + Offset 0Ah)

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

Reserved

Drive 1 DMA

Drive 0 DMA

Reserved

 

IDE

IDE DMA

Bus Master

 

Capable

Capable

 

 

Interrupt

Error

IDE Active

 

(DMACAP1)

(DMACAP0)

 

 

Status

 

(BMIDEA)

 

 

 

 

 

(IDEINTS)

 

 

 

 

 

 

 

 

 

 

 

0: Drive is

0: Drive is

 

 

0: R/W/C

0: R/W/C

0: RO

 

PIO only.

PIO only.

 

 

Software

Software

 

 

 

 

 

 

 

 

1: Drive is

1: Drive is

 

 

writes 1’ to

writes 1’ to

 

 

capable and

capable and

 

 

clear.

clear.

 

 

configured

configured

 

 

 

 

 

 

for DMA

for DMA

 

 

 

 

 

 

transfers.

transfers.

 

 

 

 

 

 

 

 

 

 

 

 

 

The Drive 0 DMA Capable bit shall be:

Set to ‘1’ when the Drive 0 (Master) has been identified and configured for DMA transfers (Ultra DMA, Multi Word DMA or Single Word DMA).

Set to ‘0’ if Drive 0 is PIO only and/or not configured for DMA operation.

The Drive 1 DMA Capable bit shall be:

Set to ‘1’ when the Drive 1 (Slave) has been identified and configured for DMA transfers.

Set to ‘0’ if Drive 1 is PIO only and/or not configured for DMA operation.

It is the responsibility of initialization software to ensure that these DMA capable bits are set so that a PCI Bus Master IDE device driver can determine which drives have been configured for DMA operation.

10.5.8Settings Checklist

The following checklists can be used in determining drive modes. Refer to the “Determining a Drive’s Transfer Rate Capabilities” and “IFB Timing Settings” sections for more information.

Table 10-13. Drive Capabilities Checklist

 

 

 

Best Ultra

Best DMA

Best PIO

IFB

 

Non Ultra DMA

Fast PIO

 

Type

 

Mode

 

 

 

DMA Mode

Mode (Fast

 

Supported?

Supported?

 

(ATA Fixed

 

(Single

Ultra

IFB

Drive

Position

(Ultra DMA

PIO Mode 2,

Best DMA Mode

Best PIO Mode

Disk or

Word 2,

DMA

Mode

 

 

Mode 0, 1,

3, 4 or

is {SW2, MW1,

>= Best DMA

 

ATAPI)

 

Multi Word

Mode

 

 

 

2, or N/A)

Compatible)

 

MW2}

Mode

 

 

 

1, 2, or N/A)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Drive 0

 

Primary

 

 

 

 

 

 

 

 

 

Master

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Drive 1

 

Primary

 

 

 

 

 

 

 

 

 

Slave

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Drive 2

 

Secondary

 

 

 

 

 

 

 

 

 

Master

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Drive 3

 

Secondary

 

 

 

 

 

 

 

 

 

Slave

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Intel® 460GX Chipset Software Developer’s Manual

10-13