RAM

RAM on the Motherboard Loses all data when PC is turned off (except data stored on CMOS chip) Loses all data when PC is turned off (except data stored on CMOS chip) Two categories Two categories –Static RAM (SRAM) Fast Fast Used as a memory cache Used as a memory cache –Dynamic RAM (DRAM) Slower; requires constant refreshing Slower; requires constant refreshing

DRAM

How Memory Caching Works

Examples of Memory Modules

DRAM SIMM technologies SIMM technologies –Can use either EDO or FPM technology DIMM technologies DIMM technologies –Can use either BEDO (burst EDO) or synchronous RAM (SDRAM) RIMM technologies RIMM technologies –Each socket must be filled to maintain continuity

Upgrading Memory What to look for when buying memory chips and modules What to look for when buying memory chips and modules How much and what kind of memory to buy How much and what kind of memory to buy Reading ads about memory modules Reading ads about memory modules Installing memory Installing memory

What to Look for When Buying Memory Chips and Modules Use type, size, density, and fastest speed supported by the motherboard Use type, size, density, and fastest speed supported by the motherboard Match tin leads to tin connectors and gold leads to gold connectors Match tin leads to tin connectors and gold leads to gold connectors Beware of remanufactured and re- marked memory chips 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 Determine how much memory you have and need Identify the number, type, and size of memory modules supported by your motherboard Identify the number, type, and size of memory modules supported by your motherboard Determine how much memory can you afford Determine how much memory can you afford Match memory modules to the motherboard Match memory modules to the motherboard

Installing Memory Protect chips against static electricity Protect chips against static electricity Usually modules pop into place easily and are secured by spring catches on both ends 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 PC gigabytes per second (GBps) of data throughput DDR2 uses a 240-pin DIMM that’s not compatible with DDR

Latency 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