Abit AR5, 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