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Description 19
IDE Support
IDE Interfaces
The ICH2’s IDE controller has two independent bus-mastering IDE interfaces that can be
independently enabled. The IDE interfaces support the following modes:
• Programmed I/O (PIO): processor controls data transfer.
• 8237-style DMA: DMA offloads the processor, supporting transfer rates of up to 16 MB/sec.
• Ultra DMA: DMA protocol on IDE bus supporting host and target throttling and transfer rates
of up to 33 MB/sec.
• ATA-66: DMA protocol on IDE bus supporting host and target throttling and transfer rates of
up to 66 MB/sec. ATA-66 protocol is similar to Ultra DMA and is device driver compatible.
• ATA-100: DMA protocol on IDE bus allows host and target throttling. The ICH2’s ATA-100
logic can achieve transfer rates up to 100 MB/sec.
✏ NOTE
ATA-66 and ATA-100 are faster timings and require a specialized cable to
reduce reflections, noise, and inductive coupling.
The IDE interfaces also support ATAPI devices (such as CD-ROM drives) and ATA devices using
the transfer modes.
The BIOS supports Logical Block Addressing (LBA) and Extended Cylinder Head Sector (ECHS)
translation modes. The drive reports the transfer rate and translation mode to the BIOS.
The S845WD1-E server board supports Laser Servo (LS-120) diskette technology through the IDE
interfaces. An LS-120 drive can be configured as a boot device by setting the BIOS Setup
program’s Boot menu to one of the following:
• ARMD-FDD (ATAPI removable media device – floppy disk drive)
• ARMD-HDD (ATAPI removable media device – hard disk drive)
SCSI Hard Drive Activity LED Connector
The SCSI hard drive activity LED connector is a 1 x 2-pin connector that allows an add-in
SCSI controller to use the same LED as the onboard IDE controller. For proper operation, this
connector should be wired to the LED output of the add-in SCSI controller. The LED indicates
when data is being read from, or written to, both the add-in SCSI controller and the IDE controller.