Devices On The Pci Bus; Small Computer System Interface (Scsi); Integrated Drive Electronics (Ide) - HP Vectra VT6 Technical Reference Manual

unpredictable, but can sometimes be tolerated (for instance, it might merely appear as a corrupted
pixel on a video display).
The HP Vectra XU 6/xxx PC and HP Vectra VT 6/xxx PC are supplied with 16 MB of main memory
as standard. The banks can be filled in any order, up to a maximum capacity of 256 MB, but
always in pairs of memory modules of the same capacity and same type (ECC or non-ECC). Only
the HP Vectra XU 6/xxx PC supports ECC (error correcting code) memory, but even this will be
disabled if any non-ECC memory is installed. Conversely, the HP Vectra VT 6/xxx PC will accept
16 MB and 32 MB ECC modules, but will treat them as non-ECC memory.
The Setup program automatically detects which memory module capacity, speed, and type (ECC
or non-ECC) is installed in each bank.
Extending the capacity of main memory, and upgrading it with faster chips, can never have a
detrimental effect on the performance. However, it can experience a law of diminishing returns, so
that upgrading the memory does not have a cost-effective impact on the performance. Finding the
correct combination is an empirical process, whether it be through simulation, or by trial and error
on the real hardware.

DEVICES ON THE PCI BUS

The PL/PCI bridge chip (OPB) is an Intel S82454KX. It is responsible for transferring data between
the Processor-Local bus and the PCI bus. It also houses the controller for the PCI bus.
• Fast-20 SCSI-2 interface ( HP Vectra XU 6/xxx PC only)
• IDE controller
• other devices in the PCI accessory slots, including:
• video controller
• LAN controller.

SMALL COMPUTER SYSTEM INTERFACE (SCSI)

An Adaptec AIC-7880 controller is integrated on the HP Vectra XU 6/xxx PC system board. It
implements Fast-20 SCSI-2 (also known as Ultra-SCSI). It attains data transfer rates up to 20 MB
per second on 8-bit wide data, single-ended. It supports up to seven SCSI devices, with a choice
of internal and external SCSI connectors. The external SCSI connector is on the rear panel.
An HP provided driver is required for the OS/2 2.11 and Windows NT operating systems; an
HP provided driver is also recommended for the Windows 3.11, Windows 95 and OS/2 Warp
Connect operating systems.
SCSI-configured-automatically (SCAM) support is provided at level 1, for Plug and Play.

INTEGRATED DRIVE ELECTRONICS (IDE)

The CMD646 chip supports Enhanced IDE (EIDE) and Standard IDE. To use the Enhanced IDE
features, though, hard disk drives must be compliant with Enhanced IDE.
Up to four IDE devices can be supported: two connected to the primary channel cable, and two to
the secondary channel cable. With EIDE, it is possible to have a fast device, such as a hard disk
drive, and a slow device, such as a CD-ROM, on the same channel without affecting the
performance of the fast device. The BIOS automatically sends a command to auto-detect each
drive, and thereby select, automatically, the fastest configuration that is supported by it. However,
in general, the primary channel cable (the grey one) is recommended for hard disk drives, and the
secondary channel cable (the red one) for CD-ROM drives.