RAM

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

DRAM

How Memory Caching Works

Examples of Memory Modules

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

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

What to Look for When Buying Memory 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

How Much and What Kind of Memory to Buy Determine how much memory

you have and need

Identify the number, type, and size of memory modules supported by your motherboard

Determine how much memory can you afford

Match memory modules to the motherboard

Installing Memory

Protect chips against static electricity

Usually modules pop into place easily and are secured by spring catches on both ends

Installing a SIMM Module

Installing a DIMM Module

Installing a DIMM Module (continued)

Installing a RIMM Module

Types of RAM

SDRAM– Systems use some form of

synchronous DRAM (SDRAM) Still DRAM, but it is synchronous

– SDRAM DIMMs came in a wide variety of pin sizes

Desktops were the 168-pin variety. Laptop DIMMs came in 68-pin, 144-pin

RDRAM

Replace SDRAM with a very fast, new type of RAM developed byRambus, Inc. called Rambus DRAM, or simply RDRAM

Came in two sizes: – A 184-pin for desktops – A 160-pin SO-RIMM for laptops

DDR SDRAM

Double Data Rate SDRAM (DDR SDRAM)

DDR SDRAM for desktops comes in 184-pin DIMMs

DDR SDRAM for laptopscomes in either 200-pin SO-DIMMs or 172-pin micro-DIMMs

DDR2

Run at a blistering PC4800. 4.8 gigabytes per second (GBps)

of data throughput DDR2 uses a 240-pin DIMM that’s

not compatible with DDR

Latency

A delay in RAM’s response time is called its Latency

RAM with a lower latency such as CL2 is faster than RAM with a higher latency such as CL3 because it responds more quickly