A Guide to Managing and Maintaining Your PC

A+ Guide to Managing and Maintaining Your PC Fifth Edition Chapter 6 Managing Memory

You Will Learn… l About the different kinds of physical memory and how they work l How to upgrade and troubleshoot memory l About Windows memory management A+ Guide to Managing and Maintaining Your PC, Fifth Edition 2

RAM on the Motherboard l l Loses all data when PC is turned off (except data stored on CMOS chip) Two categories u Static RAM (SRAM) • Fast • Used as a memory cache u Dynamic RAM (DRAM) • Slower; requires constant refreshing A+ Guide to Managing and Maintaining Your PC, Fifth Edition 3

DRAM A+ Guide to Managing and Maintaining Your PC, Fifth Edition 4

SRAM A+ Guide to Managing and Maintaining Your PC, Fifth Edition 5

COAST, an acronym for Cache On A STick, is a packaging standard ST for modules containing SRAM used as an L 2 cache in a computer. COAST modules look like somewhat oversided SIMM modules. COAST modules were somewhat popular in the early 1990 s, but as of 2004, most cache is build-in to either the CPU or the motherboard. COAST modules decoupled the motherboard from its cache, allowing varying configurations to be created. A+ Guide to Managing and Maintaining Your PC, Fifth Edition 6

Memory Technologies A+ Guide to Managing and Maintaining Your PC, Fifth Edition 7

How SRAM Is Used in Different Memory Caches A+ Guide to Managing and Maintaining Your PC, Fifth Edition 8

How Memory Caching Works A+ Guide to Managing and Maintaining Your PC, Fifth Edition 9

Dynamic RAM Technologies l l Stored on DIMM, RIMM, or SIMM modules (plug directly into motherboard) Differences among these modules: u Width of data path that each type accommodates u The way data moves from system bus to module A+ Guide to Managing and Maintaining Your PC, Fifth Edition 10

Examples of Memory Modules A+ Guide to Managing and Maintaining Your PC, Fifth Edition 11

DRAM Technologies A+ Guide to Managing and Maintaining Your PC, Fifth Edition 12

DRAM Technologies (continued) A+ Guide to Managing and Maintaining Your PC, Fifth Edition 13

DRAM l SIMM technologies u l DIMM technologies u l Can use either EDO or FPM technology Can use either BEDO (burst EDO) or synchronous RAM (SDRAM) RIMM technologies u Each socket must be filled to maintain continuity A+ Guide to Managing and Maintaining Your PC, Fifth Edition 14

Identifying the DIMM Module A+ Guide to Managing and Maintaining Your PC, Fifth Edition 15

RIMM Technologies A+ Guide to Managing and Maintaining Your PC, Fifth Edition 16

Error Checking and Parity l Parity Error-checking procedure in which every byte has an even number of ones or an odd number of ones u Older method of testing integrity of bits u • Stored in RAM or secondary medium • Sent over a communications device l Error-correcting code (ECC) u Current method of error checking that can detect and correct an error in a single bit A+ Guide to Managing and Maintaining Your PC, Fifth Edition 17

Parity A+ Guide to Managing and Maintaining Your PC, Fifth Edition 18

Other Memory Features l CAS (column access strobe) latency l RAS (row access strobe) latency l Both CAS and RAS refer to the number of clock cycles it takes to write or read a column or row of data A+ Guide to Managing and Maintaining Your PC, Fifth Edition 19

Memory Speeds: Factors to Consider l Speed of memory in ns, MHz, or PC rating l How much memory is installed l Memory technology used l CL (CAS Latency) rating CL- the number of clock cycles between the time a read command is sent and the data is available l ECC/parity or non-ECC/nonparity A+ Guide to Managing and Maintaining Your PC, Fifth Edition 20

Factors That Contribute to Memory Speed A+ Guide to Managing and Maintaining Your PC, Fifth Edition 21

PC RATINGS It is the rating standard that involves Data-transfer speed on the Memory BUS between the CPU and Memory when running any application. The rating refers directly to the maximum bandwidth obtainable and indirectly to the memory clock rate. PC 2100, for example, has a 2. 1 GB/S maximum transfer rate, and a clock rate of 133 MHz. PC 4000, as another example, has a 4 GB/S ideal transfer rate and a 250 MHz clock. To obtain the clock rate from the PCXXXX rating, divide the rating by 16. Multiply the MHz rating by 16 to obtain the bandwidth rating. The DDRXXX is just two times the actual clock speed; i. e. DDR 400 is clocked at 200 MHz. if you want know the PC-XXXX speed of the DDRXXX speed, times it by 8 DDR-I PC 1600 = DDR 200 MHz Data-rate (100 Clk x 2) 1. 6 Gb/Sec PC 2100 = DDR 266 MHz Data-rate (133 Clk x 2) 2. 1 Gb/Sec PC 2400 = DDR 300 MHz Date-rate (150 Clk x 2) 2. 4 Gb/Sec PC 2700 = DDR 333 MHz Data-rate (166 Clk x 2) 2. 7 Gb/Sec PC 3000 = DDR 366 MHz Data-rate (183 Clk x 2) 3. 0 Gb/Sec PC 3200 = DDR 400 MHz Data-rate (200 Clk x 2) 3. 2 Gb/Sec DDR-II PC 4300 = DDR 533 MHz Data-rate (266 Clk x 2) 4. 3 Gb/Sec A+ Guide to Managing and Maintaining Your PC, Fifth Edition 22

Upgrading Memory l What to look for when buying memory chips and modules l How much and what kind of memory to buy l Reading ads about memory modules l Installing memory A+ Guide to Managing and Maintaining Your PC, Fifth Edition 23

What to Look for When Buying Memory Chips and Modules l l l 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 A+ Guide to Managing and Maintaining Your PC, Fifth Edition 24

How Much and What Kind of Memory to Buy l l Determine how much memory you have and need Identify the number, type, and size of memory modules supported by your motherboard l Determine how much memory can you afford l Match memory modules to the motherboard A+ Guide to Managing and Maintaining Your PC, Fifth Edition 25

Using Motherboard Documentation to Select Memory A+ Guide to Managing and Maintaining Your PC, Fifth Edition 26

Using Motherboard Documentation to Select Memory (continued) A+ Guide to Managing and Maintaining Your PC, Fifth Edition 27

RDRAM Memory Configuration A+ Guide to Managing and Maintaining Your PC, Fifth Edition 28

Installing Memory l l Protect chips against static electricity Usually modules pop into place easily and are secured by spring catches on both ends A+ Guide to Managing and Maintaining Your PC, Fifth Edition 29

Installing a SIMM Module A+ Guide to Managing and Maintaining Your PC, Fifth Edition 30

Installing a DIMM Module A+ Guide to Managing and Maintaining Your PC, Fifth Edition 31

Installing a DIMM Module (continued) A+ Guide to Managing and Maintaining Your PC, Fifth Edition 32

Installing a RIMM Module A+ Guide to Managing and Maintaining Your PC, Fifth Edition 33

Troubleshooting Memory l l 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 A+ Guide to Managing and Maintaining Your PC, Fifth Edition 34

Windows Memory Management l Evolution of OS memory management l Windows 9 x memory management l Windows NT/2000/XP memory management A+ Guide to Managing and Maintaining Your PC, Fifth Edition 35

Evolution of OS Memory Management l DOS and Windows 9 x u l Complicated; must deal with conventional, upper, and extended memory for backward compatibility Windows NT/2000/XP u u Eliminates complexity; memory is simply memory; all memory addresses are used the same way Causes loss of backward compatibility A+ Guide to Managing and Maintaining Your PC, Fifth Edition 36

Division of Memory Under DOS and Windows 9 x A+ Guide to Managing and Maintaining Your PC, Fifth Edition 37

Assignment of Windows 9 x Memory Addresses A+ Guide to Managing and Maintaining Your PC, Fifth Edition 38

How Memory Addresses Are Used A+ Guide to Managing and Maintaining Your PC, Fifth Edition 39

How Memory Addresses Are Used (continued) A+ Guide to Managing and Maintaining Your PC, Fifth Edition 40

Memory Management Evolution A+ Guide to Managing and Maintaining Your PC, Fifth Edition 41

Windows 9 x Memory Management l l 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 A+ Guide to Managing and Maintaining Your PC, Fifth Edition 42

How Windows 9 x and DOS Manage Memory Addressing A+ Guide to Managing and Maintaining Your PC, Fifth Edition 43

Windows 9 x and DOS Utilities That Manage Memory l Himem. sys u l Device driver for all memory above 640 K Emm 386. exe u Contains software that loads device drivers and other programs into upper memory A+ Guide to Managing and Maintaining Your PC, Fifth Edition 44

Using Himem. sys A+ Guide to Managing and Maintaining Your PC, Fifth Edition 45

Using Emm 386. exe A+ Guide to Managing and Maintaining Your PC, Fifth Edition 46

Creating and Using Upper Memory Blocks A+ Guide to Managing and Maintaining Your PC, Fifth Edition 47

How Windows 9 x Manages Virtual Memory l l Automates virtual memory management Stores virtual memory in swap file and manages that memory for application programs Controlled by the VMM (memory paging) Symptoms of excessive memory paging Very high CPU use u Very slow system response u Constant hard drive use u A+ Guide to Managing and Maintaining Your PC, Fifth Edition 48

Windows NT/2000/XP Memory Management A+ Guide to Managing and Maintaining Your PC, Fifth Edition 49

How Windows 2000/XP Manages Virtual Memory l l 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 u Balance file size with disk space usage u Move paging file to a volume other than boot volume u Remember that memory dumps cannot be captured if the paging file is on a different physical disk from the OS u A+ Guide to Managing and Maintaining Your PC, Fifth Edition 50

Summary l Memory u u u l 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 9 x, and Windows NT/2000/XP manage memory A+ Guide to Managing and Maintaining Your PC, Fifth Edition 51