Specifications

Theory of Operation
4 4
4-9
Battery
The battery powers the CMOS RAM and TOD clock when system power is not
present. At 60°C, the battery should have a shelf life of over four years. In a system
that is powered on much of the time and where the ambient power-off temperature is
less than 60°C, the battery is estimated to have a life of 10 years.
If system power is present, the VME +5V STDBY voltage also powers the CMOS
RAM and TOD clock. This is done with isolation diodes, so that either the onboard
battery or the VME voltage will supply power. Neither power source will affect the
other.
The 3.0V lithium battery supplied with the EPC-8 is a Panasonic BR2330 “ coin cell”
or equivalent. It is mounted behind the reset button at the top of the EPC-8. Should
the battery fail, you may obtain and install a replacement.
Replacing the battery is a simple task. However, removing the battery will invalidate
the CMOS setup parameters if you do not put the new battery into the empty socket
within about 60 seconds. It is recommended that all setup parameters be written down
while the battery is still good, or saved using the CMOSTOOL.EXE. See the
description of the CMOSTOOL utility software in this chapter for a method to backup
CMOS parameters into a Flash memory parameter block.
To replace the battery, lay the EPC-8 flat on an ESD-protected surface. Remove the
SIMM module, following proper ESD protection procedures. Now slide the battery
out and quickly place the new battery into the empty socket. Replace the SIMM
module and reinsert the EPC-8 into the system.
Peripheral Ports
The I/O address and IRQ of the peripheral ports are determined by the CMOS
parameters established by default and modified via BIOS Setup screens.
RS-232 Port
The RS-232 port is a standard PC COM port based on the 16450 architecture. It is
normally configured as COM1 (I/O address = 3F8-3FF, IRQ4). “ COM1” is an alias
for an address and is determined by the first COM port found. If not needed, COM1
can be disabled in the BIOS Setup screen to free up the I/O address and interrupt for
usage by other expansion products.
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