Non-volatile memory usage
Non Volatile
Memory Type
Amount (Size)
Does this
memory store
customer data?
Does this
memory retain
data when
power is
removed?
What is the
purpose of this
memory?
How is data
input into this
memory?
How is this
memory write
protected?
Real Time Clock
(RTC) battery
backed-up CMOS
configuration
memory (CMOS)
256 Bytes
No
Yes
Stores system
date and time
and limited
keyboard
controller data.
Using the
F10
Setup utility or
changing the
Microsoft
Windows date
and time.
This memory is
not write-
protected. HP
recommends
password
protecting the
F10
Setup
utility.
Controller (NIC)
EEPROM
64 KBytes (not
customer
accessible)
No
Yes
Store NIC
configuration
and NIC
firmware.
Using a utility
from the NIC
vendor that can
be run from DOS.
A utility is
required to write
data to this
memory and is
available from
NIC vendor.
Writing data to
this ROM in an
inappropriate
manner will
render the NIC
nonfunctional.
Keyboard ROM
64 KBytes (not
customer
accessible)
No
Yes
Stores firmware
code (keyboard,
mouse, &
battery
management).
Programmed at
the factory.
Code is updated
when the system
BIOS is updated.
A utility is
required for
writing data to
this memory and
is available on
the HP website.
Writing data to
this ROM in an
inappropriate
manner can
render the PC
nonfunctional.
DIMM Serial
Presence Detect
(SPD)
configuration
data
256 Bytes per
memory
module, 128
Bytes
programmable
(not customer
accessible)
No
Yes
Stores memory
module
information.
Programmed by
the memory
vendor.
Data cannot be
written to this
memory when
the module is
installed in a PC.
The specific
write protection
method varies
by memory
vendor.
System BIOS
4 to 5 MBytes
Yes
Yes
Store system
BIOS code and
PC configuration
data.
System BIOS
code is
programmed at
the factory.
Code is updated
when the system
BIOS is updated.
Configuration
data and
settings are
A utility is
required for
writing data to
this memory and
is available on
the HP website.
Writing data to
this ROM in an
inappropriate
manner can
130 Chapter 15 Statement of Volatility
