Lenovo PC 300PL Understanding Your Personal Computer (6563, 6564, 6574, 6565) - Page 12

CMOS memory, Flash memory, nonvolatile RAM NVRAM

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that it must be constantly refreshed by an electric current. While the computer is turned off, no current is supplied to the modules, so no data is retained in SDRAM. RIMMs contain a type of memory known as Rambus DRAM (RDRAM) modules. RDRAM was created to help close the processor-memory performance gap at an affordable cost. The various features of RDRAM enable extremely high peak and effective bandwidth. If your computer uses RIMMs for main memory, you can get more information from the user guide publication that is provided with your computer. Both ECC (error checking and correction) and non-ECC SDRAM are supported in most models for both DIMMs and RIMMs. (Some microprocessors do not support ECC. For more information, see the user guide publication.) If a mix of ECC and non-ECC is used, the memory modules will function as non-ECC. The module connectors are located on the system board. For information about the type and amount of main memory in your computer, view the System Summary screen displayed by the Configuration/Setup Utility program. CMOS memory Your computer also uses some nonvolatile RAM (NVRAM), also called complementary metal-oxide semiconductor (CMOS) memory, for storing configuration and setup information. Powered by a small battery, CMOS retains its contents while your computer power is off. CMOS maintains information about: Date and time Security features Power-management settings Storage devices Keyboard and mouse Plug and Play configuration information Port assignments I/O addresses and interrupts Other selectable features Flash memory To store programs for startup procedures and other internal operations, some computers use read-only memory (ROM). These programs are encoded in ROM modules on the system board. ROM is nonvolatile memory, which means that it retains its contents when the computer is turned off. Generally, the contents of a ROM module cannot be modified. However, electrically erasable programmable ROM (EEPROM) modules (also referred to as flash memory) can be reprogrammed while they are in the computer. Your computer stores various system programs and data in flash memory so that they can be updated whenever enhancements are made. Flash memory contains: Basic input/output system (BIOS) Power-on self-test (POST) Configuration/Setup Utility program Vital product data (VPD) Microprocessor update code Chapter 1. Microprocessors and memory 3

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that it must be constantly refreshed by an electric current.
While the computer is turned off, no current is
supplied to the modules, so no data is retained in SDRAM.
RIMMs contain a type of memory known as
Rambus DRAM (RDRAM)
modules.
RDRAM was created to
help close the processor-memory performance gap at an affordable cost.
The various features of RDRAM
enable extremely high peak and effective bandwidth.
If your computer uses RIMMs for main memory, you
can get more information from the user guide publication that is provided with your computer.
Both ECC (error checking and correction) and non-ECC SDRAM are supported in most models for both
DIMMs and RIMMs.
(Some microprocessors do not support ECC.
For more information, see the user
guide publication.)
If a mix of ECC and non-ECC is used, the memory modules will function as non-ECC.
The module connectors are located on the system board.
For information about the type and amount of
main memory in your computer, view the System Summary screen displayed by the Configuration/Setup
Utility program.
CMOS memory
Your computer also uses some
nonvolatile RAM (NVRAM)
, also called
complementary metal-oxide
semiconductor (CMOS)
memory, for storing configuration and setup information.
Powered by a small
battery, CMOS retains its contents while your computer power is off.
CMOS maintains information about:
±
Date and time
±
Security features
±
Power-management settings
±
Storage devices
±
Keyboard and mouse
±
Plug and Play configuration information
±
Port assignments
±
I/O addresses and interrupts
±
Other selectable features
Flash memory
To store programs for startup procedures and other internal operations, some computers use
read-only
memory (ROM)
.
These programs are encoded in ROM modules on the system board.
ROM is
nonvolatile
memory, which means that it retains its contents when the computer is turned off.
Generally,
the contents of a ROM module cannot be modified.
However,
electrically erasable programmable ROM
(EEPROM)
modules (also referred to as
flash memory
) can be reprogrammed while they are in the
computer.
Your computer stores various system programs and data in
flash memory
so that they can be
updated whenever enhancements are made.
Flash memory contains:
±
Basic input/output system (BIOS)
±
Power-on self-test (POST)
±
Configuration/Setup Utility program
±
Vital product data (VPD)
±
Microprocessor update code
Chapter 1.
Microprocessors and memory
3