Chapter 4
BIOS Configuration
Fast Programmed I/O Modes: Programmed Input/Output is a method of transmitting data between devices that uses the system’s CPU as part of the data path. There are 6 modes - 5 with their own transmission speed and 1 auto mode. To use modes 3 and 4, you must be using an Enhanced IDE drive.
PIO Mode | Data Transfer | |
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Auto |
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0 | 3.3 | |
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1 | 5.2 |
28.3
311.1
416.6
32bit Transfer Mode: If On, allows for the transmission of 32 bits in parallel (i.e. at the same time). If Off, only 16 bits will be transmitted in parallel.
Entering Drive Parameters
If you select User for the drive Type, you can enter the hard disk drive parameters yourself. The drive parameters are as follows:
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| Type | The number for a drive with certain identification parameters (see the next |
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| page for a table of drive types). |
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| Cylinders (Cyl) | The number of cylinders in the disk drive. |
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| Heads (Hd) | The number of heads. |
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| The actual physical size of a sector gets progressively smaller as the track |
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| diameter diminishes. Yet, each sector must still hold 512 bytes. Write |
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| Write Precompensation | precompensation circuitry on the hard disk compensates for the physical |
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| (WP) | difference in sector size by boosting the write current for sectors on inner |
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| tracks. This parameter is the track number on the disk surface where write |
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| precompensation begins. |
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| The number of sectors per track. MFM drives have 17 sectors per track. |
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| Sectors (Sec) | RLL drives have 26 sectors per track. ESDI drives have 34 sectors per |
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| track. SCSI and IDE drives have even more sectors per track. |
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| The formatted capacity of the drive is the number of heads times the |
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| Size | number of cylinders times the number of sectors per track times 512 (bytes |
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| per sector). |
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| http://www.tyan.com | |
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