Computer Memory

Learning Objective

Computer Memory Primary Memory Secondary Memory RAM ROM Cache Storage

Computer Memory

Computer memory are the physical devices used to store programs or data on a temporary or permanent basis for use in a computer or other digital electronic device.

Two basic categories of computer memory:

Primary storage and Secondary storage

Primary Memory Primary storage or main memory stores 3 types of

information for very brief periods of time:

-Data to be processed by the CPU;

-Instructions for the CPU as to how to process the data;

-Operating system programs that manage various aspects of the computer’s operation.

Primary storage takes place in chips mounted on the computer’s main circuit board, called the motherboard.

Four main types of primary storage: register, Random Access Memory, Read Only Memory and Cache Storage

Random Access Memory

Holds its data as long as the computer is switched on

All data in RAM is lost when the computer is switched off

Described as being volatile It is direct access as it can be both

written to or read from in any order Its purpose is to temporarily hold

programs and data for processing. In modern computers it also holds the operating systems

Types of RAM

Dynamic Random Access Memory Synchronous Dynamic Random

Access Memory Direct Rambus Dynamic Random

Access Memory Static Random Access Memory Video Random Access Memory

Read Only Memory

ROM holds programs and data permanently even when computer is switched off

Data can be read by the CPU in any order so ROM is also direct access.

The contents of ROM are fixed at the time of manufacture

Stores a program called the bootstrap loader that helps start up the computer

Access time of between 10 and 50 nanoseconds

Types of ROM

Programmable Read Only Memory Erasable Programmable Read Only

Memory Electrically Erasable

Programmable Read Only Memory Flash ROM ROM catridges

Cache Memory

A smaller, high speed storage device used to increase the speed of processing by making current programs and data available to the CPU at a rapid rate.The basic characteristic of cache memory is its fast access time

Secondary Memory

Secondary memory refers to storage devices, such as hard drives and solid state drives. It may also refer to removable storage media, such as USB flash drives, CDs, and DVDs.

Unlike primary memory, secondary memory is not accessed directly by the CPU.

Instead, data accessed from secondary memory is first loaded into RAM and is then sent to the processor.

CD – Compact DISKDVD – Digital VERSATILE DISC – DIGITAL VIDEO DISC

Types of Cache Level 1 cache is built within the CPU(internal)

Level 2 cache may be on chip or nearby(external)

Made by

Nithila Adlin Thangaraj Niyati Raj Rachel Angelica Pereira Pearl Soares