Computer Notes On Computer Fundamental

Notes On Computer Fundamental

Computer:  A computer is a truly amazing machine  that  performs  a specified  sequence  of  operations  as  per  the  set  of instructions (known as programs) given on a set of data (input) to generate desired information (output ).

A complete computer system consists of four parts:

Hardware: Hardware represents the physical and tangible components of the computer.

Software: Software is a set of electronic instructions consisting of complex codes (Programs) that make the computer perform tasks.

User: The computer operators are known as users.

Data: Consists of raw facts, which the computer stores and reads in the form of numbers.

The following features characterize this electronic machine:

Speed

Accuracy

Storage and Retrieval

Repeated Processing Capabilities

Reliability

Flexibility

Low cost

CPU (Central Processing Unit): CPU is considered as the brain of the computer. It performs all types of data processing operations, stores data, intermediate results and instructions (program).It controls the operation of all parts of computer.

CPU itself has following three components:

ALU (Arithmetic Logic Unit): When the control unit encounters an instruction that involves mathematical calculation or decision/logic, it passes the control to the second component, i.e., the arithmetic logic unit (ALU). The ALU includes a group of registers – memory locations built directly into the CPU – that are used to hold data that are being processed by the current instruction.

Registers: The register is the smallest high-speed storage area in the CPU. All data must be represented in a register before it can be processed.

Control Unit: This unit controls the operations of all parts of computer but does not carry out any actual data processing operations.

These three steps constitute the data processing cycle.

Input -Input data is prepared in some convenient form for processing. The form will depend on the processing machine. For example, when electronic computers are used, the input data could be recorded on any one of several types of input medium, such as magnetic disks, tapes and so on.

Processing – In this step input data is changed to produce data in a more useful form. For example, paychecks may be calculated from the time cards, or a summary of sales for the month may be calculated from the sales orders.

Output – The result of the proceeding processing step are collected. The particular form of the output data depends on the use of the data. For example, output data may be pay-checks for employees.

Language Processors:

Assembler: This language processor converts the program written in assembly language into machine language.

Interpreter: This language processor converts a HLL(High Level Language) program into machine language by converting and executing it line by line.

Compiler:-It also converts the HLL program into machine language but the conversion manner is different. It converts the entire HLL program in one go, and reports all the errors of the program along with the line numbers.

Software

Software represents the set of programs that govern the operation of a computer system and make the hardware run.

There are two types of software

System Software: The system software is collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software are generally prepared by computer manufactures. System software serves as the interface between hardware and the end users.

Examples: Operating System, Compilers, Interpreter, Assembler etc.

Application Software: It is the set of programs necessary to carry out operations for a specified application.

Application software can subdivide into three categories:

Analog computers

Analog computers always take input in form of signals.

The input data is not a number infect a physical quantity like temp., pressure, speed, velocity.

Signals are continuous of (0 to 10 V).

Accuracy 1% Approximately.
Example: Speedometer.

Digital Computers

These computers take the input in the form of digits & alphabets & converted it into binary format.

Digital computers are high speed, programmable electronic devices.

Signals are two level of (0 for low/off , 1 for high/on).

Accuracy unlimited.

Examples: Computer used for the purpose of business and education are also example of digital computers.

Hybrid Computer

The combination of features of analog and digital computer is called Hybrid computer.

The main examples are central national defense and passenger flight radar system.

They are also used to control robots.

Super Computer

The biggest in size.

Most Expensive

It can process trillions of instructions in seconds.

This computer is not used as a PC in a home neither by a student in a college.

Used by Govt. for different calculations and heavy jobs.

Supercomputers are used for the heavy stuff like weather maps, construction of atom bombs, earthquake prediction etc.

Mainframes

It can also process millions of instruction per second.

It can handle processing of many users at a time.

Less expensive than Supercomputer

It is commonly used in Hospitals, Air Reservation Companies as it can retrieve data on huge basis.

This is normally too expensive and out of reach from a salary-based person.

It can cost up to thousands of Dollars.

Mini Computer

These computers are preferred mostly by small type of business personals, colleges etc.

These computers are cheaper than above two.

Its an intermediary between microcomputer and mainframe.

Micro Computer/ Personal Computer

It is mostly preferred by Home Users.

Cost is less compared to above.

Small in size.

A microcomputer contains a (a central processing unit on a microchip), in the form of read-only memory and random access memory, and a housed in a unit that is usually called a motherboard .

Notebook Computers

Notebook computers typically weigh less than 6 pounds and are small enough to fit easily in a briefcase.

Principal difference between a notebook computer and a personal computer is the display screen.

Many notebook display screens are limited to VGA resolution

Programming Languages

There are two major types of programming languages. These are Low Level Languages and High Level Languages.

Low Level languages are further divided in to Machine language and Assembly language.

Low Level Languages: The term low level means closeness to the way in which the machine has been built. Low level languages are machine oriented and require extensive knowledge of computer hardware and its configuration.

Machine Language: Machine Language is the only language that is directly understood by the computer. It does not need any translator program. We also call it machine code and it is written as strings of 1’s (one) and 0’s (zero). When this sequence of codes is fed to the computer, it recognizes the codes and converts it in to electrical signals needed to run it.

For example, a program instruction may look like this:  1011000111101

It is not an easy language for you to learn because of its difficult to understand. It is efficient for the computer but very inefficient for programmers. It is considered to the first generation language.

Advantage:

Program of machine language run very fast because no translation program is required for the CPU.

Disadvantages

It is very difficult to program in machine language. The programmer has to know details of hardware to write program.

The programmer has to remember a lot of codes to write a program which results in program errors.

It is difficult to debug the program.

Assembly Language

It is the first step to improve the programming structure. You should know that computer can handle numbers and letter. Therefore some combination of letters can be used to substitute for number of machine codes.

The set of symbols and letters forms the Assembly Language and a translator program is required to translate the Assembly Language to machine language. This translator program is called `Assembler‘. It is considered to be a second-generation language

Advantages:

The symbolic programming of Assembly Language is easier to understand and saves a lot of time and effort of the programmer.

It is easier to correct errors and modify program instructions.

Assembly Language has the same efficiency of execution as the machine level language. Because this is one-to-one translator between assembly language program and its corresponding machine language program.

Disadvantages:

Assembly language is machine dependent.

A program written for one computer might not run in other computers with different hardware configuration.

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