Module Descriptions; Workstation Interface Board (Wib_P1); Motherboard/Backplane (Rmb) - Compaq PowerStorm 1000 Owner's Manual

Technical Description

6.3 Module Descriptions

The following sections contain technical descriptions of the boards and modules that make
up the DIGITAL PowerStorm 1000 graphics subsystem.

6.3.1 Workstation Interface Board (WIB_P1)

The Workstation Interface Board is implemented in the form factor of the host computer
bus. It provides a high-speed memory-mapped connection to the graphics subsystem via
the Hbus. It is through the Workstation Interface Board that the host computer may access
any device in the system that interfaces to the Dbus.
The Workstation Interface Board is a single slot PCI bus board that provides the interface
between the AlphaStation system and the PowerStorm 1000 graphics subsystem.
The Workstation Interface Board interfaces to a common "HBus" cable between the
AlphaStation system and the graphics subsystem. In addition, the Workstation Interface
Board provides DMA capabilities from the host memory to the graphics subsystem. This is
a critical feature for off-loading the host from transfer operations due to the high
bandwidth requirements needed to maintain the rendering performance goals of the
graphics subsystem.
The Workstation Interface Board does not provide console support. Instead, the
AlphaStation system will have VGA support provided by a separate VGA Module. A VGA
cable connects the VGA Module in the AlphaStation system to the graphics subsystem's
(entry and full PowerStorm 1000) Standard Resolution Module. An "enable/disable"
switch is provided to switch between the VGA video source and the graphics subsystem's
video source. The Workstation Interface Board contains a PROM for future support.

6.3.2 Motherboard/Backplane (RMB)

The motherboard provides the interconnect and power distribution between the various
modules that make up the PowerStorm 1000 graphics subsystem. In addition to the
numerous connectors that are required to implement this interconnect, the motherboard
contains active components to distribute clocks, provide Dbus bridges that are required to
maintain acceptable skew within the system, Dbus control logic, and a serial I.D. PROM
for identification.
The motherboard contains nine slots to support the following modules:
•
One Graphics Interface Module
•
One Vertex Module
•
Up to four Image Rendering Modules
•
One Video Memory Module per Image Rendering Module pair
•
One Standard Resolution Module or High Resolution Module
6–4 DIGITAL PowerStorm 1000 Graphics Subsystem Owner's Guide