Eurotech Appliances CPU-1461 - Manual (Page 37)

PC/104-Plus – CPU-1461 Module 37
PIO Mode
PIO is a special data-transfer system between two or more EIDE devices, where all the data pass through
the processor. There are five transfer rates, called PIO mode n (with n=0..4). If the Auto (autodetect) option
is disabled, the PIO mode must be specified.
Option Description Note
PIO-0 Transfer Rate of 3.3 MBps
PIO-1 Transfer Rate of 5.2 MBps
PIO-2 Transfer Rate of 8.3 MBps
PIO-3 Transfer Rate of 11.1 MBps
PIO-4 Transfer Rate of 16.6 MBps
Translation Mode
Modern hard-disks have more cylinders than maximum number of cylinders permitted by DOS, so,
theoretically, a DOS machine couldn’t use a modern big-sized hard disk. This problem is solved using a
special addressing mechanism. This “mechanism” is called translation. The most common translation
method are LBA (Logical Block Addressing) and ECHS (Enhanced Cylinders - Heads - Sectors).
Option Description Note
LBA LBA translation
ECHS Extended CHS translation
Cylinders
Number of hard-disk cylinders (normally written on the disk label). If the auto-detection is used (suggested
method!), the cylinders value is ignored by the BIOS.
Option Description Note
0..65536 Number of cylinders
Heads
Number of hard-disk heads (normally written on the disk label). If the auto-detection is used (suggested
method!), the heads value is ignored by the BIOS.
Option Description Note
0..64 Number of heads
Sect/Tr
Number of sectors per track (normally written on the disk label). If the auto-detection is used (suggested
method!), the sectors value is ignored by the BIOS.
Option Description Note
0..255 Number of sectors per track
Size (MB)
This is the hard-disk size, in Mbytes, calculated by the BIOS, using either the autodetect method or the user
hand-written values (for cylinders, heads and sectors).
• Note: the size cannot be changed directly by the user.