Data General AViiON Series, Customer Documentation

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Preparing to Install VME Options
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VME SCSI-2 Adapter (VSA). Each VSA board in a computer system supports
two SCSI-2 buses, each of which can be single-ended or differential. The SCSI
devices connect directly to the controller board mounted in your computer unit.
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VME LAN Controller (VLC, VLCi). Each VLC board in a computer system
supports an Ethernet LAN; the transceiver in the network connects directly to
the controller board in your computer unit.
•
VME Distributed Token Ring Controller (VTRC). Each VTRC board in a
computer system supports an IEEE 802.5 token-ring LAN and connects to the
LAN via a Trunk Access Unit, also called a Media Access Unit.
•
VME Fiber Distributed Data Interface (FDDI) Controller (VFC). Each
VFC board in a computer system supports connection to a 100 Mb/sec fiber–optic
FDDI network.
Review the configuration guidelines in your system documentation to determine
which of these options your computer system supports. If your proposed expansion
appears acceptable, continue with the next section to ensure that the power supply
for your computer system can support the entire new configuration.
Calculating Power Requirements
The proposed configuration of boards, drives, and other devices powered by your
computer unit cannot consume more electrical power than the computer’s power
supply can provide. Before you begin installing VME options, calculate the electric
current and power requirements of the proposed configuration, and then compare
those totals with your power supply’s maximum output. If the new configuration
exceeds system power limits you will need to eliminate some part of the proposed
system.
This section explains how to calculate and compare the necessary power
information; it also contains a calculation form and completed sample form. The
procedure may appear complicated, but actually it requires only that you record
information listed in other manuals, perform some simple arithmetic, and then
compare the results.
To calculate the current totals and total wattage of the planned configuration, follow
the steps below. Use the Current and Power Calculation Form in Figure 1–1 and
the example of Figure 1–2 as you proceed; Appendix B contains extra forms that
you can copy.
1. Refer to your computer’s expanding and/or maintaining manuals for a list or
table of the amperes provided by your power supply for the +5, +12, and –12
voltage sources. Enter those values as maximum amperes in the “Available”
column of the Power Supply/Amperage section on your calculation form
(Figure 1–1).
2. Refer to the technical specifications in your expanding and/or maintaining
manuals for the current requirements of every device in your planned
configuration that will draw power from your computer power supply. Enter
each value on your calculation form.