Ram Memory Types

7/31/2019 Ram Memory Types

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Types of RAM

(Random Access Memory)

Information Technology


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What is RAM Memory?

RAM typically resides on Memory Modules

A RAM Memory chip is an integrated circuit made of millions

of Transistors and Capacitors

Most RAM is Volatile (loses electrical charge when powergoes off)

There are various types of RAM (DRAM, SRAM, VRAM)

Virtual Memory (An extension of RAM on the hard drive)


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Typically RAM chips reside on memory

modules. Four main types exist. SIMMs

DIMMs

SODIMMs

RIMMs


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SIMMs

Single Inline MemoryModule

Pins on opposite sidesform a single set ofcontacts


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DIMMs

Dual Inline Memory Module

168 Pins on opposite sidesof the circuit board form

separate connections


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SODIMMs

Small Outline Dual In-line Memory Module

A much smaller form of memory

Used in Notebook computers and AppleiMac desktops


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RIMMs

RAMbus Inline Memory Module RDRAM

Comparable in size and pin configuration toDIMM but uses a special memory bus togreatly increase speed.


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How does RAM store

information?-Address lines-Transistors

-Data lines-Capacitors


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Most RAM must be recharged

constantly

Volatile Memory losses contents when power isremoved


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Some RAM types use

Parity Checking

Even Parity Checking, parity bit is setto 0 when byte is even.

001001000 9th bit is parity bit 0

Odd Parity Checking, parity bit is setto "1" when byte is even.

111001111 9th bit is parity bit of 1


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Error Control

High-end servers often have a form oferror-checking known as error

correction code (ECC).

Bits can be corrected after failure,

however, if more than one bit is corruptedthe entire byte of data is lost.


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RAM Types

What are some different types ofRandom Access Memory ?


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Types of Dynamic RAM (DRAM)

SDRAM Synchronous DRAM

Synchronized to the system clock

DDR SDRAM (Double Data Rate SDRAM)

Transfer data twice for each clock cycle

Rambus DRAM (RDRAM)Faster than SDRAM chips because theyuse pipelining techniques


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Types of Dynamic RAM

Stores 1s and 0s on capacitors

Must be recharged every millisecond, or

every one thousandth of a second

Many different types exist (previous slide)


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Fast Page Mode DRAM

First form of DRAM

Maximum transfer rate to L2 cache is

approximately 176 megabytes per second.


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EDO DRAM

EDO = Extended Data Out

Resides on SIMMs

Sends and receives data simultaneously

Maximum transfer rate to L2 cache isapproximately 264 megabytes per second.


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Synchronous DRAM

Resides on DIMMs

Faster than previous DRAM because it is

synchronized with the system clock

Maximum transfer rate to L2 cache isapproximately 528 megabytes per second.

Most common choice of Pentiums untilrecently


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Double Data-rate SDRAM

Resides on DIMMs

Also known as SDRAM II

Faster than SDRAM because it transfersdata twice for each clock cycle

Commonly used in PCs


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RAMbus DRAM

Resides on RIMMs

Uses a pipelining technique to increase

speed

RDRAM memory chips work in parallel toachieve a data rate of 800+ MHz.


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DRDRAM Direct Rambus DRAM by Rambus, Inc.

Often called PC800 RAM (doubling the

Pentium 4 chips 400 MHz bus speed)

Like DDR SDRAM, it transfers data on therising & falling edges of the clock cycle

Uses 2 data channels to improve transferrates


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Static RAM

Often used for Cache Memory

Very fast and reliable because these chips

do not have to be recharged as often asDRAM chips hence the term static

SRAM chips: more expensive than DRAM


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Static RAM

Cache Memory (Static RAM) helps speedup the microprocessor.

Cache Memory stores frequently used dataand instructions.


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Static RAM

Personal Computers have 2 and perhaps3 types of cache memory:

L1 (Level 1) Cache (8KB to 128KB)

L2 (Level 2) Cache (64KB to 4MB)

L2 Advanced Transfer Cache on currentmicroprocessors (built on the chip)


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Static RAM

L3 (Level 3) Cache is cache separate fromthe microprocessor chip and is on the

motherboard. L3 Cache exists only on computers that

use the L2 Advanced Transfer Cache.


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Static RAM

A computer with L2 cache usuallyperforms at speeds 10 to 40 percent faster

than those without cache. Servers and workstations can have at least

2MB of L2 or L3 cache.


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SGRAM

Synchronous Graphics RAM SGRAM is a variant of SDRAM

SGRAM makes use of block-writes to

increase video processing speeds.

SGRAM is single-ported so the CPU cannotwrite to it at the same time the image is

being refreshed. SGRAM is used in high-end graphics cards


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How much RAM do you need?

What OS are yourunning ?

What applications doyou run?

Computer animationand graphics?

Several functions?

Win 2000/XP 128MB

Win 95/98 64 MB

Linux 64 MB

Mac OS 128 MB


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Virtual Memory

Virtual memory takes the place of RAMmemory

You should have a 2:1 ratio of RAM toVirtual Memory


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Modifying Virtual Memory in

Windows


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Modifying Virtual Memory in

Windows 2000


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End of RAM presentation

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Ram Memory Types