By increasing the buffer size of the onboard video memory from 512 KB to 1 MB (with one, 40-pin 256 K x 16, 70 ns fast-page DRAM), the controller can support 132- column text modes and high resolution graphics with a maximum of 1024 x 768 x 64 K colors. It also provides hardware accelerated bit block transfers (BitBLT) of data.
SCSI Controller
The system board includes two PCI-based Adaptec AIC-7870 fast/wide SCSI-2 controllers (channels A and B) integrated as 32-bit PCI bus masters. The controllers support data path widths of 8-bit (narrow SCSI) at a data transfer rate of 10 MB/sec and 16-bit (wide SCSI) at a data transfer rate of 20 MB/sec. As PCI bus masters, these controllers support data transfer rates of 133 MB/sec.
You can connect up to seven 8-bit narrow SCSI devices or up to fifteen 8-bit narrow and/or 16-bit wide SCSI devices and one controller (maximum of seven 8-bit narrow devices) to each channel. The devices include, for example, tape drives, printers, optical media drives, and others.
The SCSI controller provides active negation outputs, controls for external differential transceivers, a disk activity output, and a SCSI terminator power-down control.
Active negation outputs reduce the chance of data errors by actively driving both polarities of the SCSI bus and avoiding indeterminate voltage levels and common- mode noise on long cable runs. The SCSI output drivers can directly drive a 48 mA, single-ended SCSI bus with no additional drivers.
No additional logic, termination, or resistor loads are required to connect up to seven 8-bit narrow SCSI devices or up to fifteen 16-bit wide SCSI devices to each SCSI-2 channel on the system board.
SCSI-2 SCA-Compatible Backplane
The SCSI-2 SCA backplane for the ProServa PH is configured as two SCSI continuous fast/wide SCSI buses (A and B) for connecting all hot-swap SCA- compatible hard drives installed in the hot-swap bays. This allows fast drive installation and removal, as each hard drive plugs directly into a SCA connector on the backplane. The backplane also acts as the termination point for all installed SCSI hard drives and sets the hard drive IDs.
The backplane also supports up to three SCSI devices installed in the
5 1/4-inch bay, including the installed SCSI-2 CD-ROM reader. The SCSI-2 SCA backplane supports fast/wide SCSI-2 (20 MB per second) data transfers to the 3 1/2- inch hard drives. The backplane also supports SCSI-1 (5 MB per second) and fast/narrow SCSI-2 (10 MB per second) devices. See Chapter 5, "SCSI Hot-docking Backplane," for information on configuring the backplane.
ECC Memory Module
