Unit 2 Hardware and Software of Microcomputer

A computer is a fast and accurate symbolprocessing system. It can accept, store, process data and produce outputresults. A computer can automatically process data without human intervention.However, it must be given a set of instruction to guide it, step by step,through processes. The set of instructions is called a program. The program isstored physically inside the machine, making it a program.

All computer systems of interest to us aresimilar. They contain hardware components for input, central processing unitand output. The system on the small-scale is called a microcomputer orminicomputer. Continuing up the size scale, the mainframe computer is one thatmay offer a faster processing speed and a greater storage capacity than atypical mini. Finally comes the supercomputer, designed to process complexscientific applications, which is the largest and fastest.

Although the capacity of computers' storagelocations is varied, every computer stores numbers, letters, and othercharacters in a coded form. Every character in the storage is represented by astring of 0s and 1s, the only digits founded in the binary numbering system.BCD and ASCII are popular computer codes.

CPU

CPU is the abbreviation of Central ProcessingUnit, which is the heart of a computer like the head of a family. Once thepower of a computer is turned on, all the behaviors are under the control ofCPU. CPU is in an iron box together with other devices such as disk drives, amain memory and a switching power supply etc. In Chinese, the iron box isconventionally called the mainframe. On the back of the mainframe box, thereare various ports, with which CPU may be linked with input and output devices.

Memory

Primary memory is known as random accessmemory (RAM) and simple named memory. It is the storage area within thecomputer that holds programs and data during processing. Memory is onlytemporary storage area; when processing is complete, memory is cleared. Theuser needs to load or enter data and programs into the computer memory whenusing any application on the computer.

Different computers have different amounts ofmemory space, referred to as memory size, ranging from 4, 8 megabytes to64megabytes. Today, the memories of some microcomputers even can be expandableto hundreds of megabytes.

Computer software

Most people think of software as all of theamazing application programs available today for microcomputers. But there areother forms of computer software that make it possible to use applicationprograms. Software is the collective name for all the programs and instructionsthat direct a computer's operations. Generally software can be divided intothree types: system software, application software and support software, systemsoftware monitors and controls the system's hardware. Application softwareperforms specific tasks for the user. Support software is a series of software,which support development and maintenance of other software. Software iscreated through the use of programming languages.

The computer Language

The role of a program is to deliver user'sintention to a computer and direct it to work. That is to say, a program is adialogue tool for interacting between a man and a computer, as well as a bridgeto transmit information. In general, the characters, phases and their syntaxrules for programming are generally called “programming language”.

Programming languages are divided into threetypes: machine language, which is also called an instruction system, is theonly one used directly by computers. The assembler language is a kind ofsymbolic language. It adopted some mnemonic symbols which can show the instructionalfunctions to present the content of the program. The high-level language is aprogramming language based on English. Its operators and expressions aresimilar to ordinary mathematical formulas. General users can easily master ahigh-level language and make programs in it.

Programming

Programming is, at its simplest, the waypeople tell computers what to do, when to do it, and how to do it. A program isa specific set of instructions written by one or more people, which direct theaction of a computer system. It may be a very simple or complicated set ofinstructions. It may be written by a beginning computer user or by a topcomputer expert. It may be written in simple English or in a language spokenonly by computers. Just as writing a fiction, programming is a process ofcreating art.

What is Object Oriented Programming？

Object oriented programming (OOP) is a newway of approaching the job of programming that differs from traditionalprogramming because it uses objects as data structures to enhance productivity,simplify programming, get reusability and improve software reliability. Allobject oriented programming languages have three characteristics in common:objects, polymorphism and inheritance. Let's take a look at these concepts.

Object is a data structure that contains bothstructured information and related operations. An object can contain otherobjects. In this way, the object is given both data properties and behaviors,and so object oriented programs can better reflect the real world they aretrying to simulate. Polymorphism essentially means that one name can be usedfor several related but slightly different purposes. Inheritance is the processby which one object can acquire the properties of another object. This isimportant because it supports the concept of classification. For example, a reddelicious apple is a part of the classification apple, which in turn is a partof the fruit class, which is under the larger class food.