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Functional Description
5-66
82801AA and 82801AB Datasheet
5.14
IDE Controller (D31:F1)
The IDE interface of the ICH can support several types of data transfers:
Programmed I/O (PIO):
Processor is in control of the data transfer.
8237 style DMA:
DMA protocol that resembles the DMA on the ISA bus, although it does not
use the 8237 in the ICH. This protocol off loads the processor from moving data. This allows
higher transfer rate of up to 16 MB/s.
Ultra ATA/33:
DMA protocol that redefines signals on the IDE cable to allow both host and
target throttling of data and transfer rates of up to 33 MB/s.
Note:
The ICH0 (82801AB) does not support Ultra ATA/66. If software attempts to
program an IDE drive to run ATA/66 timings, the ICH0 will see short strobes
(from ATA/33 perspective) and will throttle the performance. This will result in
transfer rates that are slower than if the drive were programmed for ATA/33 mode.
Ultra ATA/66 (ICH: 82801AA only):
DMA protocol that redefines signals on the IDE cable
to allow both host and target throttling of data and transfer rates of up to 66 MB/s.
The ICH has integrated termination series resistors on the data and control lines as listed in
Table 5-50
.
NOTES:
1. Simulation data indicates that these integrated series termination resistors are a nominal 33 ohms but can
range from 28 ohms to 46 ohms.
2. Simulation data indicates that these integrated series termination resistors are a nominal 22 ohms but can
range from 19 ohms to 29 ohms.
Table 5-49. System Power State Definition (ICH: 82801AA only)
State
Enter State
Exit State
Pre-Boot
ICH has left G1 or G2 by deasserting SLP_S3#
CPURST# deasserted or powerbutton
override
G0
CPURST# deasserted
Write to SLP_EN register or powerbutton
override
G1
Write to SLP_EN register with SLP_TYP for S1-S4
ICH deasserts SLP_S3# after a wake event
or powerbutton override
G2
Write to SLP_EN register with SLP_TYP for S5 or
powerbutton override
ICH deasserts SLP_S3# after a wake event
Table 5-50. IDE Integrated Series Termination Resistors
Signal
Integrated Series Termination
Resistor Value
Notes
PDD[15:0], SDD[15:0]
approximately 33 ohms
1
PDIOW#, SDIOW#, PDIOR#, PDIOW#, PDREQ,
SDREQ, PDDACK#, SDDACK#, PIORDY, SIORDY,
PDA[2:0], SDA[2:0], PDCS1#, SDCS1#, PDCS3#,
SDCS3#, IRQ14, IRQ15
approximately 22 ohms
2