Other Pci Accessory Devices - HP Vectra VT6 Technical Reference Manual

Transfer Rates Versus Modes of Operation
The controller supports 32-bit Windows and DOS I/O transfers (many IDE controllers use Windows
integral IDE driver which only supports 16-bit I/O transfers). It has PCI master capability, and
supports programmed I/O (PIO) modes up to mode 4 and direct memory access (DMA) modes up
to mode 2 (giving a cycle time of 120 ns, and a transfer rate of 16.7 MB per second, in both
cases). The five PIO modes allow the following transfer rates:
Mode
Cycle time (ns)
Transfer rate (MBytes/s)
The three 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 4 or 5 MBytes per second. Operated in MASTER mode, though,
the IDE controller is allowed to work autonomously of the CPU, and the full 16.7 MBytes per
second transfer rate can be achieved, with less than 33% occupancy of the PCI bus (so allowing
the CPU to get on with other work for more than 67% of the cycle times, whilst the IDE transfers
are going on in parallel).
Disk Capacity Versus Modes of Addressing
The amount of addressable space on a hard disk drive 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). If the Setup field has been
set to automatic, the logical block addressing (LBA) mode will be selected for each device that
supports it.
Cylinders
per Device
CHS 64
ECHS 64
LBA -

OTHER PCI ACCESSORY DEVICES

PCI accessory boards are for high-speed peripheral accessories. There are four slots on the PCI
bus for accessory boards. One of these is already occupied by the video controller board, and a
second (on the HP Vectra XU 6/ xxx PC ) by the LAN board; these are described in the next
chapter. The fourth slot is a combination slot with the ISA bus.
0 1
600 383
3.33 5.22
0 1
480 150
4.2 13.3
Heads per Sectors
Cylinder per Track
16 1024
256 1024
- 256 M
(=228)
2 3 4
240 180 120
8.33 11.1 16.7
2
120
16.7
Bytes per Bytes per
Sector Device
512 528 M
512 8.4 G
512 137 G