Computer Memory Types Structure And Functions | Lesson 3

Computer Memory Types Structure And Functions

Storage and Address concept of Memory-Primary and Secondary, Bit, Byte capacity, Address, Content (numeric, ASCII characters), RAM, ROM, Secondary Memory-Magnetic (Hard disk, Floppy) Optical (CD, DVD) : Structure and Capacity.

Introduction :-

In 1833, the famous British mathematician Charles Babbage first thought about storing information in a computer, and he thought that if computers could store data or information, the importance of computers would increase to a great extent.

At that time, due to the lack of progress in science and technology, he could not implement this idea. But his later scientists were able to implement his efforts and as a result of his thinking we see the presence of memory in modern computers. Babbage is called the father of the modern computer for his groundbreaking ideas and efforts.

Computer memory and its functions

The unit of computer through which any information is stored is called memory unit or memory store.

The classification of computer memory is as follows

Computer memory is mainly divided into three parts: 

1. Primary memory 
2. Secondary memory
3. Cache memory

Primary Memory :

The internal memory directly connected to the computer CPU is called primary memory. The main feature of this memory is that the data coming from the input unit is first stored in this memory. As long as there is electrical current in the computer, its function is on.

Modern electronic memories are each semiconductor ICs. (I.C.) technology, they are sometimes called semiconductor memories.

The primary memory of a computer can be mainly divided into two parts

• RAM (Random Access Memory) 
• ROM (Read Only Memory)

RAM :

RAM is a temporary memory where information or data is stored while the computer is running and can be used by the user for all kinds of tasks.

The main memory of the computer is RAM. All information is stored in RAM after the computer is switched on.

Features of RAM :

(1) RAM can read and write computer data.

(2) RAM is a temporary memory because the information stored in it is erased when the computer is switched off. So RAM is called Volatile Memory.

RAM is divided into two parts

• STATIC RAM
• DYNAMIC RAM

ROM :

ROM is a permanent memory. Where information or data is stored during the creation of the computer. to this not easily changed.

Features of this memory are :

• When any information is written in this memory, it remains permanent.
• This memory can only read data. 
• In ROM even when the computer is switched off saved data is not deleted. In some ROMs however written information can be deleted by special means.
• These memories are called non-volatile memories.

ROM can be divided into three parts (Memory).

• PROM (Programmable Read Only Memory)
• EPROM (Erasable Programmable Read Only Memory)
• EEROM (Electrically Erasable Read Only Memory)

Some tasks that are performed repeatedly in the computer, such as reading characters from the keyboard after switching on the computer, displaying characters on the monitor screen, etc., are required every time the computer is turned on. These instructions are written into ROM.

Function of ROM :

• Tests the computer's input and output devices when the computer is turned on.

• Helps load the operating system on the computer.

Secondary Memory :

Floppy disks, hard disks, CDs (compact disks) used in computers are called secondary memory.

Features of Secondary Memory :

(1) Secondary memory is required to store large amount of data.

(2) Secondary memory is used to store any information permanently.

(3) There is no loss or destruction of data even if the computer is turned off.

(4) If needed in future, useful information is available from secondary memory.

Usage Generally :

• I cannot store any processed data in the primary memory (RAM and ROM). So we use secondary memory to permanently store any processed information and retrieve that information at a later time.
• Large amounts of data can be stored on floppies, hard disks, CDs and DVDs. Floppy used in computers
• (Floppy) and Hard Disk (Hard Disk) are disks of magnetic nature and CD or Compact Disk and DVD (Digital
• Versatile Disk) is a disk of optical nature. They are discussed below.

Floppy

Floppy disks are made of a thin plastic material called Mylar. It looks like a round disc. The disc is coated with ferrous oxide. The disc is very thin and the disc is covered in a hard and sturdy square plastic cover to protect the disc from getting damaged by dust or dirt. Use of floppy drive is required to play floppy disk. A computer can have multiple floppy drives.

Floppy size :

Computer floppies are mainly of two sizes – 5.25 inches and 3.5 inches. Currently 5.25 inch floppies are not used much. Most of the computers we use today use 3.5 inch floppies.

Data Storage Capacity of Floppy :

A maximum of 1.2MB (megabytes) of data can be stored on a 5.25-inch floppies. On the other hand, a maximum of 1.44MB (megabytes) of data can be stored on a 3.5-inch floppies.