Computer Notes on Fundamentals of Computer

Notes on Fundamentals of Computer

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 

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.

Fig: The relationship between different hardware components

 Language Processors:

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

This type of software is tailor-made software according to a user’s requirements.

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 is also an example of digital computers.

Hybrid Computer

• The combination of features of an analog and digital computer is called a Hybrid computer.
• The main examples are central national defence 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 a 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 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.
• The 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 into 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 into 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 a 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 a 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 a 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 on other computers with different hardware configuration.

High-Level languages

You know that assembly language and machine level language require deep knowledge of computer hardware whereas in a higher language you have to know only the instructions in English words and logic of the problem irrespective of the type of computer you are using.

• Higher level languages are simple languages that use English and mathematical symbols like +, -, %, / for its program construction.
• You should know that any higher level language has to be converted to machine language for the computer to understand.
• Higher level languages are problem-oriented languages because the instructions are suitable for solving a particular problem.

For example, COBOL (Common Business Oriented Language) is most suitable for a business-oriented language where there are very little processing and huge output.

There are mathematically oriented languages like FORTRAN (Formula Translation) and BASIC (Beginners All-purpose Symbolic Instruction Code) where very large processing is required.

Thus a problem-oriented language designed in such a way that its instruction may be written more like the language of the problem. For example, businessmen use the business term and scientists use scientific terms in their respective languages.

Advantages of High-Level Languages

• Higher level languages have a major advantage over machine and assembly languages that higher level languages are easy to learn and use.
• It is because that they are similar to the languages used by us in our day to day life.