TYPES OF MEMORIES IN COMPUTER SYSTEM AND

MEMORY STORAGE DEVICES

Made By – Juhi AnandCSE ,SECTION N2

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INTRODUCTION In computing memory refers

to the physical devices used to store programs (sequences of instructions) or data (e.g. program state information) on a temporary or permanent basis for use in a computer or other digital electronic device.

TYPES OF MEMORIES

PRIMARY OR MAIN MEMORY

Main memory is divided into two parts : Random Access memory (RAM), should

be better known as Read Write Memory (RWM).

Read Only Memory (ROM) .

RANDOM ACCESS MEMORY (RAM)

A RAM memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM), a transistor and a capacitor are combines to create a memory cell, which represents a single bit of data.

TYPES OF RAM

STATIC RAM Semi conductor memory Uses flip flop to store each bit of memory

so does not need to be periodically refreshed

Fast and consumes low power Expensive and has complex structure(6

transistors) so not used for high capacity applications

DYNAMIC RAM Stores each bit of memory in capacitor

in an intrgrated circuit Real capacitors leak charge so

capacitors need to be refreshed periodically

Simple structure (1 capacitor and 1 transistor per bit) so it has very high density

READ ONLY MEMORY(ROM)

New contents cannot be added

Used to store the instructions of routine type,permanent in nature and used to control or supervise the hardware

TYPES OF ROM PROGRAMMABLE

READ ONLY MEMORY (PROM)

Programmed to record the information using a facility PROM – programmmer

Once the information is recorded it cannot be changed

ERASABLE PROGRAMMABLE READ ONLY MEMORY (EPROM)

Information can be erased and chip can be reprogrammed to record different information using PROM programmer

In formation is erased using UV radiations

It is of two types- Ultra Voilet Erasable Programmable Read Only Memory (UEPROM) and Electrically Alterable Programmable Read Only Memory (EAPROM)

ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM)

Memory is erased by electrical signals

Provides easy means to store temporary or permanent information in the form of ROM memory

CACHE MEMORY Faster and expensive than

RAM It improves the computer’s

performance and is less than 512 KB

Processor can use it to store frequently accessed data and programs instructions

It is of two types – L1 / primary cache(inside microprocessor) and L2/ secondary cache(in the mother board or near the microprocessor)

SECONDARY MEMORY It supplements the

main memory. It is permanent memory.

Programs, data entered into the system, intermediate results and final results produced are stored in the secondary memory

CLASSIFICATION

MAGNETIC BASED STORAGE DEVICES

Prepared using using formatting

Data is recorded on disk in concentric circular bands called tracks.

MAGNETIC TAPE FLOPPY DISK HARD DISK

OPTICAL STORAGE MEDIA Stores large amount of

data in some formats as much as the entire hard disk

Reads data by focusing a laser- generated beam of light on light on disc’s surface

CD- ROM discs DVD- ROM discs

MEMORY HIERARCHY Ranking of

computer memory devices, with devices having the fastest access time at the top of hierarchy, and devices with slower access time but larger capacity and lower cost at lower levels

THANKS