IDE Configuration

12.2.13SDMATIM–Synchronous DMA Timing Register (Function 1)

Address Offset:

4A-4Bh

Default Value:

0000h

Attribute:

Read/Write only

This register controls the timings used by each Synchronous DMA enabled device. For nonsynchronous DMA operation, this register should be left programmed to its default value.

Bit

Description

 

 

15:14

Reserved.

 

 

13:12

Secondary Drive 1 Cycle Time (SCT1): These bit settings determine the minimum data write

 

strobe Cycle Time (CT) and minimum Ready to Pause time (RP).

 

00: CT = 4 PCICLK, RP = 6 PCICLK

 

01: CT = 3 PCICLK, RP = 5 PCICLK

 

10: CT = 2 PCICLK, RP = 4 PCICLK

 

11: Reserved

 

 

11:10

Reserved.

 

 

9:8

Secondary Drive 0 Cycle Time (SCT0): These bit settings determine the minimum data write

 

strobe Cycle Time (CT) and minimum Ready to Pause time (RP).

 

00: CT = 4 PCICLK, RP = 6 PCICLK

 

01: CT = 3 PCICLK, RP = 5 PCICLK

 

10: CT = 2 PCICLK, RP = 4 PCICLK

 

11: Reserved

 

 

7:6

Reserved.

 

 

5:4

Primary Drive 1 Cycle Time (PCT1): These bit settings determine the minimum data write

 

strobe Cycle Time (CT) and minimum Ready to Pause time (RP).

 

00: CT = 4 PCICLK, RP = 6 PCICLK

 

01: CT = 3 PCICLK, RP = 5 PCICLK

 

10: CT = 2 PCICLK, RP = 4 PCICLK

 

11: Reserved

 

 

3:2

Reserved.

 

 

1:0

Primary Drive 0 Cycle Time (PCT0): These bit settings determine the minimum data write

 

strobe Cycle Time (CT) and minimum Ready to Pause time (RP).

 

00: CT = 4 PCICLK, RP = 6 PCICLK

 

01: CT = 3 PCICLK, RP = 5 PCICLK

 

10: CT = 2 PCICLK, RP = 4 PCICLK

 

11: Reserved

 

 

12-8

Intel® 460GX Chipset Software Developer’s Manual