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1A+ Guide to Managing and Maintaining Your PC, Fifth Edition
Understand @ Managing Memory
The term memory applies to any electronic
component capable of temporarily storing
data.There are two main categories of
memories which are internal memory and
auxiliary memory.
Internal Memory is memory that temporarilymemories. Uses by micro conductors, i.e fast
specialized electronic circuits.
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Understand @ managing memory(continue)
Auxiliary memory is memory that stores
information over the long term such as hard drive,
optical storage devices, cd-rom, dvd-rom and
others.
2A+ Guide to Managing and Maintaining Your PC, Fifth Edition
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3A+ Guide to Managing and Maintaining Your PC, Fifth Edition
RAM on the Motherboard
Loses all data when PC is turned off (except
data stored on CMOS chip)
Two categories Static RAM (SRAM)
Fast
Used as a memory cache
Dynamic RAM (DRAM)
Slower; requires constant refreshing
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DRAM
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SRAM
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Memory Technologies
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How SRAM Is Used in DifferentMemory Caches
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How Memory Caching Works
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Dynamic RAM Technologies
Stored on DIMM, RIMM, or SIMM modules
(plug directly into motherboard)
Differences among these modules:
Width of data path that each type accommodates
The way data moves from system bus to module
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Examples of Memory Modules
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DRAM Technologies
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DRAM Technologies (continued)
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DRAM
SIMM technologies
Can use either EDO or FPM technology
DIMM technologies
Can use either BEDO (burst EDO) or synchronous
RAM (SDRAM)
RIMM technologies
Each socket must be filled to maintain continuity
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Identifying the DIMM Module
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RIMM Technologies
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Error Checking and Parity
Parity Error-checking procedure in which every byte has
an even number of ones or an odd number of ones
Older method of testing integrity of bits Stored in RAM or secondary medium
Sent over a communications device
Error-correcting code (ECC)
Current method of error checking that can detect
and correct an error in a single bit
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Parity
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Other Memory Features
CAS (column access strobe) latency
RAS (row access strobe) latency
Both CAS and RAS refer to the number of
clock cycles it takes to write or read a column
or row of data
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Memory Speeds: Factors toConsider
Speed of memory in ns, MHz, or PC rating
How much memory is installed
Memory technology used
CL rating
ECC/parity or non-ECC/nonparity
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Factors That Contribute toMemory Speed
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Upgrading Memory
What to look for when buying memory chips
and modules
How much and what kind of memory to buy
Reading ads about memory modules
Installing memory
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What to Look for When BuyingMemory Chips and Modules
Use type, size, density, and fastest speed
supported by the motherboard
Match tin leads to tin connectors and gold
leads to gold connectors
Beware of remanufactured and re-marked
memory chips
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How Much and What Kind ofMemory to Buy Determine how much memory you have and
need
Identify the number, type, and size of memorymodules supported by your motherboard
Determine how much memory can you afford
Match memory modules to the motherboard
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Using Motherboard Documentationto Select Memory
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Using Motherboard Documentationto Select Memory (continued)
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RDRAM Memory Configuration
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Installing Memory
Protect chips against static electricity
Usually modules pop into place easily and are
secured by spring catches on both ends
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Installing a SIMM Module
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Installing a DIMM Module
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Installing a DIMM Module(continued)
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Installing a RIMM Module
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Troubleshooting Memory
What to do if the computer does not recognize
new SIMMs, DIMMs, or RIMMs, or memory
error messages appear
Recurring errors during normal operations can
mean unreliable memory
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Windows Memory Management
Evolution of OS memory management
Windows 9x memory management
Windows NT/2000/XP memory management
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Evolution of OS MemoryManagement
DOS and Windows 9x
Complicated; must deal with conventional, upper,
and extended memory for backward compatibility
Windows NT/2000/NT
Eliminates complexity; memory is simply
memory; all memory addresses are used the sameway
Causes loss of backward compatibility
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Division of Memory Under DOSand Windows 9x
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Assignment of Windows 9xMemory Addresses
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How Memory Addresses AreUsed
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How Memory Addresses AreUsed (continued)
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Memory Management Evolution
Wi d 9 M
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Windows 9x MemoryManagement
Views and manages memory addresses as
DOS did
Runs in protected mode and uses virtual
memory; does a better job managing extended
memory than DOS
H Wi d 9 d DOS
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How Windows 9x and DOSManage Memory Addressing
Wi d 9 d DOS U ili i
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Windows 9x and DOS UtilitiesThat Manage Memory
Himem.sys
Device driver for all memory above 640K
Emm386.exe
Contains software that loads device drivers andother programs into upper memory
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Using Himem.sys
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Using Emm386.exe
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Creating and Using UpperMemory Blocks
H Wi d 9 M
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How Windows 9x ManagesVirtual Memory Automates virtual memory management
Stores virtual memory in swap file andmanages that memory for application
programs Controlled by the VMM (memory paging)
Symptoms of excessive memory paging
Very high CPU use Very slow system response
Constant hard drive use
Wi d NT/2000/XP M
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Windows NT/2000/XP MemoryManagement
H Wi d 2000/XP
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How Windows 2000/XPManages Virtual Memory Default size of paging file is set to 1.5 times
amount of RAM installed
Guidelines for managing paging files
Set initial and maximum size of file to same value Balance file size with disk space usage
Move paging file to a volume other than bootvolume
Remember that memory dumps cannot be capturedif the paging file is on a different physical diskfrom the OS
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Summary
Memory
Required in order for a system to work
Stored on microchips, which are often stored on
memory modules (SIMMs, DIMMS, RIMMs)
Adding more memory can improve system
performance
How DOS, Windows 9x, and Windows
NT/2000/XP manage memory