Non-Volatile Memory Usage - HP 255 G4 Maintenance And Service Manual

Non-volatile memory usage

Non Volatile
Memory Type
Real Time Clock
(RTC) battery
backed-up
CMOS
configuration
memory (CMOS)
Controller (NIC)
EEPROM
Keyboard ROM
DIMM Serial
Presence
Detect (SPD)
configuration
data
System BIOS
Intel
Management
Engine
Firmware
(present only in
models ending
in a 'p' or 'w' or
with Intel
Centrino Pro
technology)
Amount Does this Does this
(Size) memory memory
store retain data
customer when power is
data? removed?
256 Bytes No Yes
64 Kbytes No Yes
(not
customer
accessible)
64 Kbytes No Yes
(not
customer
accessible)
256 Bytes No Yes
per memory
module,
128 Bytes
programma
bl e (not
customer
accessible)
4 to 5 Yes Yes
MBytes
1.5 or Yes Yes
5MByte
What is the How is data input into
purpose of this memory?
this memory?
Stores system Using the F10 Setup utility
date and time or changing the
and limited Microsoft® Windows®
keyboard date & time.
controller
data.
Store NIC Using a utility from the
configuration NIC vendor that can be run
and NIC from DOS.
firmware.
Stores Programmed at the
firmware code factory. Code is updated
(keyboard, when the system BIOS is
mouse, & updated.
battery
management).
Stores Programmed by the
memory memory vendor.
module
information.
Store system System BIOS code is
BIOS code and programmed at the
PC factory. Code is updated
configuration when the system BIOS is
data. updated. Configuration
data and settings are
input using the F10 setup
utility or a custom utility.
Stores Management Engine Code
Management is programmed at the
Engine Code, factory. Code is updated
Settings, via Intel secure firmware
Provisioning update utility. Unique
Data and iAMT Provisioning Data can be
third party entered at the factory or
data store. by an administrator using
the Management Engine
(MEBx) setup utility. The
How is this memory
write protected?
This memory is not
write-protected. HP
recommends
password protecting
the F10 Setup utility.
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.
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.
Data cannot be written
to this memory when
the module is installed
in a PC. The specific
write protection
method varies by
memory vendor.
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.
The Intel chipset is
configured to enforce
HW protection to block
all direct read/write
access to this area. An
Intel utility is required
for updating the
firmware. Only
firmware updates
digitally signed by
Non-volatile memory usage 87