Data representation. Programming Languages. Early Computing Machines and inventors

1) Data representation

People are thinking of the computers as complex mechanism, but this  Mechanism know only two things: “ON” and “OFF”.

This “ON”/“OFF” two-state system is called the binary system. If signal exists, then it represent as one, if  signal not exist, then it represent as zero. Each 0 or 1 in the binary system is called a bit. By means of the single bits computer cannot store all the numbers, letters, and special characters.The bits are put together ingroups, usually of 8 is called a bytes. By means of the bytes computer can represent all numbers, letters, and special characters. 1024 bits is called a kilobyte. We must number 2 raise to the 10 power. One million of bits is called a megabyte, the gigabyte it is the billion of bytes. A computer word  it is a number of bits that constitute a common unit of information. The length of a word varies by computers. Common word length in bits are 8(micro),16(mini),32(mainframe),64(super).

By means of the C.W. we can represent computer address, microprocesors comands and data.

A computer word size is very important. The larger the word size, the more powerful the computer. Computer  to process data, use variable-length words or fixed-length word.

Programming Languages

The only language computers can understand is called machine code. This code consist of  the 0s and 1s. It is necessary to use symbolic languages that are easier to understand.  By using a special program, these languages can be translated into machine code. Basic language is similar to the machine code is low-level language. In These languages each instruction is equivalent to a single machine code instruction, it is machine-oriented language. The Most popular compiler of the low-level language is Assambler.

To make the program easier to write were developed Higher-level language such as Algol C++ Packal. High level programming languages are languages in which each instruction or statement translate to the several machine code instructions. It is problem-oriented language.

It has two advantages to writing programs. Firstly The programmer writes the program instructions at the abstract language. Secondly by means of the Compiler,THe  program should be translated into the machine code so that the CPU could understand it. This  program can  RUN on different types of computers.

Now, the scientists  work on the creation the computers with the A.I., which  may be able to understand the human language.

GENERATIONS OF COMPUTER SYSTEMS

The first generation computers introdused in 1950. They used vacuum tubs for calculation and control. Their memories were constructed of liquid mercury delay lines. They were very big, very expansive and unreliable. Some of them were as large as a room. They were slow in operation.

The second generation computers appeared in the late 1950s. They used transistors for calculation and control  and their memories were made of magnetizable cores. Their size was reduced and their reliability was improved significantly.

The third generation computers were introduced in the mid 1960s. They had their processor and they were made of integrated circuits.

The 3-rd generation also introduced system software technologies such as: Operating systems and Data base management systems.They have input and output devices and disc drive.

On-line systems were widely developed throughout the 3-rd generation they were also based on the serial data processing, and were not fast enough.

The Fouth generation computers appears in the 1970s. They used lage-scale integration for  calculation control and  memories. The  base part of this coputers is general-purpose processor (microchip).

The 5 generation. The was coined by the Japanese to describle the powerful intelligent oputers. It is computers with AI. It is expert systems and computers Which understand natural leduage.

Computer networks

By itself, a computer is a valuable device. But there are limits to the amount of information and the variety of programs  can be assembled on even the largest individual computer. The usefulness of any computer increases  when it is linked to other computers, since networks allow users to pool their resources. Larger networks, which can collect the resources of thousands