Data General AViiON 4600 Series, Customer Documentation

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Expanding and Maintaining Your Computer System
6-3
014–002091
•
Review your system software documentation, Release Notice(s), Updates, and
application documentation. These books can provide valuable information you
should know
before you install any new system components. A review of your
system documentation might, for example, reveal an incompatibility between your
current configuration and a proposed hardware addition.
•
Carefully consider site requirements, whether or not your system needs additional
drivers for the planned expansion, cable and cable-length restrictions, and any
other hardware or software configuration restraints.
•
If you intend to add or replace a mass-storage device on a system SCSI bus, make
certain your new drive complies with the parameters described in Chapter 4
Setting Up and Installing a SCSI Bus."
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 combination 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 options, you should 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 procedures may
appear complicated; they actually require only that you perform some simple addition,
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 6Ć2 and the
example of Figure 6Ć1 as you proceed; you might want to copy these forms for future
use.
1.
Refer to Table A-1 in Appendix A of this manual 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.
NOTE:
Be certain to include all devices that draw current power from the
computer unit's power supply, but not those that draw power from
another source. For example, your calculations must include
keyboards for graphics monitors and mouse devices, but monitors,
most keyboards, and mass-storage subsystems do not draw current
from the system power supply. Do not list the fan assembly, which has
exclusive use of the +9Ćvolt dc power supply output.
If your configuration includes devices not listed in this manual or
Setting Up and Installing VMEbus Options in AViiON

Systems , refer
to the device-specific technical manuals to determine current draw
( the amount of electric current the device draws from your power
supply).