Abit IT5E Series, User Manual

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General Discussion about HDD Installation
E-1
Appendix E General Discussion
about HDD
Installation
Most of the present HDDs use IDE interface. Installing an IDE hard
disk does not require a huge amount of intelligence like installing the
driver for a SCSI hard disk, but this means that the user often must install
the hard disk by himself and cope with all the problems he may encounter.
Here, we will try to help you solve these possible problems.
The data stored in the hard disk are accessed through a chipset
located on the mainboard. You probably often hear about the PIO mode,
Master mode or DMA mode of HDD. These modes reflect the way data is
transferred from and to the IDE drive and the mainboard.
What is the PIO mode? When the system needs to access hard disk
data, the CPU delivers input/output (I/O) orders through the chipset on
the mainboard to the hard disk drive, and than puts these data into the
system memory. This is the PIO mode.
What is the Master mode? When the system needs to access hard disk
data, these data are directly accessed from the hard disk by the chipset on
the mainboard (using a DMA or a PIO mode), and then the data is put into
the memory. In this case, the CPU does not participate in the data transfer.
What is the DMA mode? Usually, DMA mode refers to accessing the
hard disk data by the chipset, it does not refers to data transfer mode.
Here are some examples of data transfer rates for IDE HDD with
PIO interface:
PIO Mode 0 The fastest data transfer rate reaches 3.3Mbyte/sec
PIO Mode 1 The fastest data transfer rate reaches 5.2Mbyte/sec
PIO Mode 2 The fastest data transfer rate reaches 8.3Mbyte/sec
PIO Mode 3 The fastest data transfer rate reaches 11.1Mbyte/sec
PIO Mode 4 The fastest data transfer rate reaches 16.6MByte/sec