HP Stream, Maintenance And Service Manual

Page: 82 / 91

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 Mic
rosoft
Windows date
and time.
This memory
is not write-
protected.
HP recommends
password
protecting the
F
10 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 websit
e. 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 modul
e 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
input A utility
is required for
writing data to
this memory
and is available
on the HP websit
e. Writing data
to this ROM in an
inappropriate
manner can
74 Chapter 10 Statement of Volatility