Learn Computer Organization & Operating System “Introduction of Computer ” Lesson 1

Computer Organization & OS: User perspective

Introduction

The computer is an electronic machine made with electronic devices. It accepts the raw data through input device processes it based on the set of instructions given (called programs) and produces the information as output on the output device . Computer hardware refers to the physical components or peripherals ( physical parts of a computer such as CPU , Mother Board , RAM , keyboard , Mouse , monitor , Optical disk drive , storage disk etc. all of which are physical objects that you can actually touch.

A computer requires both hardware and software to operate. It cannot operate solely on the hardware. However, a computer is a dumb machine. It cannot operate on its own. It requires human interaction (user) for its operation. However, a computer user cannot interact directly with the computer hardware. He/She requires some kind of interface to interact with the computer’s hardware. This interface is known as the operating system (OS).

Definition of Computer

The computer is an electronic machine made with electronic devices. It accepts the raw data through input device processes it based on the set of instructions given (called programs) and produces the information as output on the output device. The important feature of computers is its storage capability which can store the information and can be retrieved as and when required.

Characteristics of Computer

Computers are popular because of following characteristics: „h Speed: Computer can perform a task much faster than done manually.

Accuracy: Computer gives accurate results compared to task done manually.

Storage: Computer stores the information in its main memory and the same can be retrieved based on the requirement.

Multitasking: Computer performs multiple tasks simultaneously. For example, one can use the computer to take a printout of an inventory report and at the same time can use it to draft letters.

Communication: Computer can be used to exchange information between two or more computers. Internet is the best example of this.

Application Areas of Computers

The influences of computers are widespread and are used in various application areas mentioned below :

1. Business Area
2. Entertainment Area
3. Education Area
4. Medicinal Area
5. Finance / Banking Area The Language of Computers

Computer being electronic machine it knows only “ON” or “OFF” (‘0’ or ‘1’). Any data that is to be fed, processed or stored should be converted into combination of 0s and 1s. This is called binary notation and 0 or 1 is called a Bit.

1. Bit is a basic memory unit.
2. Byte is unit of data consists of 8 bits
3. Kilo Byte (KB) equals 1024 – Bytes
4. Mega Byte (MB) equals 1024 Kilo Bytes
5. Giga Byte (GB) equals 1024 Mega Bytes

Data Transfer Inside a Computer

All the data movements within a computer occur through buses. A bus is a group of electrical conductors, mostly wires, running parallel to each other carrying a charge from one point to another within the computer. A bus can be copper traces on a circuit board or wires in a cable.

Usually, a bus is found in multiples of eight (8, 16, 32, 64, and so on). In the early computers, manufacturers used a set of eight wires for constructing buses. This allows the transmission of eight bits, or one byte, of information at a time.

The bus width is one of the important characteristic to optimize the performance of the computer. Wider the bus, more bits can be transferred simultaneously resulting in faster data transmission. 8-bit bus can carry only 8-bits of data at a time, while the 32-bit bus can carry 32-bits of data simultaneously. As a result a bus with 32-bit width will transfer more amount of data compared to a bus with 8-bit width.
In a computer, a bus is used to connect the main processor, the memory, and all input/output devices. If the bus connects main processor with the computer memory, then it is called a system bus or front side bus. If the bus connects input, out put devices, then it is called I/O bus.

Parallel and Serial Communication

As discussed earlier the basic function of computer is to take an input, process it and produce the desired output. In order to perform this function, computer exchange data amongst its various components. In certain computer components, these data are send in serial order, one after the other in a sequence. This means only a single bit can be send at any given time. This type of communication is called serial communication.

The following diagram illustrates the serial communication:

In the preceding figure, observe that only one bit travels at a time between the two points X and Y

However, the disadvantage of serial communication is that it provides a slow mean of data communication. And with the advancement in computer development, faster means of communication is required. Hence to fasten the communication more wires are used to connect the components of the computer. In this way we can send multiple bits simultaneously. This enables the data to travel faster. This type of communication is called parallel communication.

The following diagram illustrates the parallel communication:

In the preceding figure, observe that four bits travel at a time, through four wires, between the two points X and Y.

We can draw analogy of the computer communication with cinema ticket booking. Suppose a cinema hall has only a single ticket booking counter. The ticket clerk can handle only one customer at a time and since there is only one counter only a single customer can book a ticket at any given time. This may result in long queue and more time for a customer to reach the booking counter and then getting the ticket. However, if there are multiple windows for booking tickets, result in multiple customers to book a ticket at any given time.

In addition, the queue will also get divided amongst the multiple counters resulting in shorter queue. This will result a customer to get the cinema ticket in much lesser time.
In the above analogy, if the cinema hall has a single ticket booking counter, then it is serial communication. And if the cinema hall has multiple ticket booking counters, then it is a parallel communication.