HP Vectra XW Technical Reference Manual page 23

Transfer Rates Versus
Modes of Operation
Disk Capacity Versus
Modes of Addressing
automatically, the fastest configuration that it supports. However, in general,
the primary channel cable is recommended for hard disk drives, and the
secondary channel cable for CD-ROM drives. Indeed, if a CD-ROM is placed
on the same channel as a hard disk drive, problems could be experienced
activating the 32-bit access drivers.
The controller supports 32-bit Windows I/O transfers. The five supported PIO
modes allow the following transfer rates:
Mode
Cycle time (ns)
Transfer rate (MBytes/s)
The three supported DMA modes allow the following transfer rates:
Mode
Cycle time (ns)
Transfer rate (MBytes/s)
Operated in slave mode, the IDE controller saturates the PCI bus with
transfers, thus limiting the actual achieved transfer rate to 10 MBytes per
second. Operated in master mode, though, the IDE controller is able to work
autonomously of the processor, and the full 16.7 MBytes per second transfer
rate can be achieved, with less than 33% occupancy of the PCI bus.
The amount of addressable space on a hard disk is limited by three factors:
the physical size of the hard disk, the addressing limit of the IDE hardware,
and the addressing limit of the BIOS. The Extended-CHS addressing scheme
allows larger disk capacities to be addressed than under CHS, by performing
a translation (for example regrouping the sectors so that there are twice as
many logical tracks as is possible under the CHS addressing scheme).
Cylinders per
Device
CHS 64
ECHS 64
LBA -
If the Setup field has been set to
(LBA) mode will be selected for each device that supports it.
0 1
600 383
3.33 5.22
0 1
480 150
4.2 13.3
Heads per
Sectors per Track
Cylinder
16 1024
256 1024
- 256 M (=2
automatic
2 System Board
Devices on the PCI Bus
2 3
240 180
8.33 11.1
2
120
16.7
Bytes per
Sector
512
512
28
) 512
, the logical block addressing
4
120
16.7
Bytes per
Device
528 M
8.4 G
137 G
15