The Complete A+ Guide
to PC Repair 5/e Update
Chapter 6
Memory
Chapter Objectives
After completing this chapter you will be able to:
• Differentiate between different memory
technologies
• Plan for a memory installation or upgrade
• Install and remove memory chips
• Describe how memory works with the operating
system
• Optimize memory for Windows-based platforms
• Troubleshoot memory problems
• Understand the benefits of teamwork
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Memory Overview
Types of Memory:
•
RAM (Random Access Memory) is volatile
memory found on the motherboard and stores
the operating system, the software
applications, and the data being used by
software.
•
ROM (Read Only Memory) is a non-volatile
type of memory that keeps data in chips even
when the computer is shut off.
Types of RAM:
•
DRAM (Dynamic RAM) is cheaper than
SRAM, but slower. It requires periodic
refreshing of the electrical charges holding the
1s and 0s.
•
SRAM (Static RAM) is faster, but more
expensive than DRAM. It is also known as
cache memory or L2 cache.
Tech Tips
• The CPU should never have to
wait to receive an instruction
• Using pipelined burst cache
speeds up processing for
software applications.
Memory Terms
• Refreshing – Rewriting the information
inside memory chips.
• Nanosecond – A billionth of a second.
• Pipeline – Separate internal data buses that
operate simultaneously inside the processor.
• Cache Memory – Designed to increase processor
efficiency.
− Can be found on the motherboard, but normally is found inside the
CPU or CPU housing.
− Cache memory holds the most frequently used data so the CPU
does not return to the slower motherboard DRAM chips to obtain
the data.
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Memory Physical Packaging
• DIP (Dual In-line Package) – A chip
that has a row of legs running down
each side.
• SIMM (Single In-line Memory
Module) – Available in 30-pin and
72-pin configurations.
• DIMM (Dual In-line Memory
Module) – 168-pin, 184-pin and 240pin configurations.
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Memory Physical Packaging
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Planning the Memory Installation
Key points for planning a memory installation
- Refer to the system or motherboard
documentation to see what type of memory is
supported
- Determine what features are supported
- Determine how much memory is needed
- Determine how many of each memory module is
needed
- Research prices and purchase memory
module(s)
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Tech Tips
• Use the type of memory chips
recommended by the motherboard
manufacturer.
• It is best to use the manufacturer-specified
type of memory chips.
– The chipset and motherboard design are very
specific as to what type, and features the
memory chips can have.
Memory Technologies
• Technology has provided faster DRAM speeds
without increasing the cost too greatly.
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Memory Technologies (cont.)
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Types of DIMMs
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Memory Features
• Parity – A method for checking the
accuracy of data in or out of the
memory chips
• Non-parity – Memory chips that do not use
any error checking
• ECC (Error Correcting Code) – An alternative
to parity checking that uses a mathematical
algorithm to verify data accuracy
© 2012 Pearson Addison-Wesley. All rights reserved.
Memory Limitations
• Specific operating systems have a memory limitation.
• 32-bit Windows has a 4GB memory limitation.
– Do not install over 4GB on a computer with a 32-bit
operating system such as XP, Vista, or 7.
– Even with 4GB, the 32-bit operating system shows less
than 4GB because some of that memory space is used for
things attached to the PCI bus.
• The motherboard has a memory maximum
Amount of Memory to Install
• Memory is one of the easiest upgrades to
do to a computer to improve performance.
• Amount of memory needed depends on
– Maximum allowed by the operating system
– Types of applications used
– How many applications the user wishes to
have open at the same time
– Type of computer
– Maximum allowed by motherboard
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Minimum Memory
Recommendations
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Planning the Memory Installation
Common Memory Capacities:
• DIMM Modules
− 256MB, 512MB, 1GB, 2GB, 4GB, 8GB
• RIMM Modules
– RIMM is not an acronym and is a trademark
of Rambus incorporated for the Direct
Rambus or DRAM (RDRAM) modules
− 64MB, 128 MB, 256MB, 512MB
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Planning the Memory Installation
The Amount of Memory to Install
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Planning for Memory
• Single-sided memory - A memory
module that the CPU accesses at one
time.
• The module has one “bank” of memory and 64 bits
are transferred out of the memory module to the
CPU.
• More appropriately called single-banked memory.
• Note: that the memory module may or may not have
all of its “chips” on one side
© 2012 Pearson Addison-Wesley. All rights reserved.
Planning for Memory
• Double-sided memory - A single memory
module that contains two memory modules in
one container.
− Data is still sent to the CPU 64 bits at a time.
− Some use the terms single-sided and double-sided to
describe memory modules that have chips on one
side (single-sided) or both sides (double-sided).
− Another name is double-ranked memory.
Planning for Memory
Dual-channel - The motherboard memory
controller chip handles processing of memory
request more efficiently by handling two memory
paths simultaneously.
Tech Tip
• Dual-channel should use exact
memory module pairs.
– Channel A and Channel B (sometimes
labeled Channel 0 and Channel 1) should
have matching memory modules.
– Buy a kit to ensure that the two modules are
exact.
Dual-Channel Examples
Dual-Channel Example
Planning for Memory
• The researching and buying step of planning for
your memory installation/upgrade is most likely
the step that can make your head spin.
− Different Web sites list memory differently.
− Some give you too much information, some too little.
Planning for Memory
• A confusing aspect of buying memory is memory
speed.
− Memory speed can be represented as ns
(nanoseconds), MHz, or the DDR PC rating.
• Access Time - The amount of time it takes to
retrieve data from memory or a device.
• CL rating (CAS latency rating)- The amount of
time in clock cycled that passes before the CPU
moves on to the next memory address.
• A CL2 rating is faster than a CL4 rating.
Nanoseconds and the Race
Track
• The lower the number of nanoseconds,
the faster the access time of the memory
chips.
– Think of access time like a track race - the
person with the lowest time wins the race and
is considered to be the fastest.
– Chips with lower access times (lower amount
of nanoseconds) are faster than those with
higher access times (larger numbers).
Laptop Memory
• SO-DIMM (small outline-DIMM)- Special,
smaller DIMM used in laptop computers.
• microDIMM- A type of DIMM used in portable
computers such as a laptop.
• SO-RIMM (small outline-RIMM)- Special, smaller
RIMM used in laptop computers.
Installing Memory Overview
• Determine which chip capacities can be
used for the system. Look in the
documentation included with the
motherboard or the computer for this
information.
• Determine how much memory is needed.
• Determine what capacity chips go in each bank
referring to the documentation of the system or
motherboard.
• Think ahead
Memory Safety Reminder
• Before installing a memory module,
power off the computer, disconnect
the power cord from the back of the
computer, and use proper antistatic procedures.
– Memory modules are most susceptible to ESD. If
ESD damages a memory module, a problem may not
appear immediately and could be intermittent and
hard to diagnose.
Removing a DIMM/RIMM
• To remove a DIMM or a RIMM, push down
on the outside edges of the DIMM’s
retaining tabs. The DIMM/RIMM lifts
slightly out of the socket.
Installing a DIMM/RIMM
• To install a DIMM/RIMM, align the notches with
the socket and press down until the tabs close.
• DIMM/RIMM is inserted straight down into a
socket.
• If the DIMM/RIMM does not insert easily, check
the notch for proper alignment.
Windows Disk Caching
• Virtual Memory - A method of
simulating extra memory by
using the hard disk space as if it
were RAM.
• Swap file - A temporary file in hard disk space
used by Windows that varies in size depending
on the amount of RAM installed, available hard
drive space, and the amount of memory needed
to run the application.
Windows Disk Caching
• Pages – In Windows disk caching, memory
space is divided into 4KB blocks called pages.
• The operating system swaps or pages the application
to and from the temporary swap file on the hard drive
as needed if the amount of RAM is not large enough
to handle the application.
• PAE (physical address extension) - A feature
provided by Intel that allows up to 64GB of
physical memory to be used for motherboards
that support it.
Hard Drive Swap File Tip
• If multiple hard drives are available, a technician
might want to move the swap file to a different
drive.
– Always put the swap file on the fastest hard drive
unless that hard drive lacks space.
– It is best to keep the swap files on a hard drive that
does not contain the operating system.
– You can configure the computer to place the swap file
on multiple hard dives.
Monitoring Memory Usage Under
Windows
• Performance utility Windows utility
accessed through
Task Manager that
monitors memory and
other hardware
parameters usage
aspects.
Old Applications Under Windows
- NTVDM (NT Virtual DOS Machine)- Simulates a
DOS environment inside NT Workstation and
higher when an 8- or 16-bit application is being
run.
- Many dated applications do not operate in the
NT/2000/XP environment because these
applications frequently make direct calls to
hardware, which NT, 2000, XP, Vista, and 7 do
not allow.
Troubleshooting Memory
Problems
• The following tips help with memory management
-
Add more RAM
Check installation
Empty Recycle Bin
Adjust virtual memory size
Change the virtual memory settings
Do not put the swap file on multiple partitions that reside on the
same hard drive.
Put the swap file on a hard disk partition that does not contain
the operating systems.
Put the swap file on the fastest hard drive.
Remove the desktop wallpaper scheme or use a plain one.
Adjust your Temporary Internet Files setting
Defragment the hard drive.
Flash Memory
• Flash memory- A type of non-volatile memory
that holds data when the power is off.
• CompactFlash
• SD, miniSD, microSD
• USB flash drives - Sometimes called a flash
drive or a memory stick, USB flash drives allow
storage via a USB port,
• Formatting – use the device
Tech Tip
• No.1 cause of Flash Drive failure is improper
removal
– When finished using the Flash drive, double-click the
Remove Hardware icon located in the System Tray.
– The icon has a green arrow.
– You may have to click on the left arrow or up arrow to
see this icon.
– Click Safely Remove Hardware.
– Select the appropriate Flash drive, then click Stop
and OK.
– When a message appears that you can safely remove
the drive, pull the Flash drive from the USB port.
Soft Skills - Teamwork
- Much of a technician’s work is
completed alone.
- Technician’s have one or more
peers, a supervisor, and a network
of partners such as suppliers, subcontractors,
and part-time help.
- Do not lose sight of the business-first mentalityremember technicians play a support role.
- As a technician, you are an EXPENSE on the
spreadsheet.
- Technicians should be good team players and
have good sportsmanship.
Questions???