COMPUTER
A computer is a machine that processes the information given to it very quickly, performs arithmetic and logical operations automatically, and can obtain new information. Computer is the term computer, which comes from the Latin word computare.
Computers perform high-speed operations and can store the information they obtain for a long time, enabling them to be used in many fields. It should be known that computers cannot perform any operation on their own. However, it is the result of commands given to it by humans through programs.
The unprocessed information given to the computer is input (data), and the results of mathematical and logical operations with them are output (information).
HISTORY OF THE COMPUTER
Humankind’s first calculation tool was their fingers. They used their fingers to make calculations and display numbers. It is necessary to mention the Abacus, which is believed to have been used by the Chinese as the first calculation tool around 600 BC.
The first mechanical calculator was developed in the 17th century by the French mathematician and theologian Blaise Pascal (1623-1662). It was created by the French mathematician and theologian Blaise Pascal (1623-1662). He built a machine called Pascaline that could add and subtract.
In 1671, the German mathematician Gottfried Wilhelm Leibniz (1646-1716). He further improved Pascal’s addition and subtraction machine and developed a calculator capable of multiplication, division and square rooting. This device, called the Leibniz wheel, was the first necessary calculator used in the commercial field.
With the development of science and technology, calculator discoveries and inventions began. Among the works in this field was the British mathematician and researcher Charles Babbage (1791-1871). He worked on the machines he developed in 1820 and the analytical machine in 1832. The difference machine was used to prepare trigonometric and logarithmic tables, while the analytical machine was a fully automatic and general-purpose calculator in today’s sense.
Later, Lady Ada Lovalance (1815-1852) worked on using punched cards in the analytical machine. As the first computer programmer, Lady Ada Lovalance introduced the concept of loop and subroutine used in computer programming in the studies on punched cards.
The English mathematician George Boole (1815-1864) was the most important contributor to computer technology development. He introduced one of the most essential topics of modern mathematics, now known as Boolean algebra.
The 1900s was the year of the development of computer technologies and the establishment of large companies to create the computer. American engineer Herman Hollerith (1860-1929). The results of punch card machines in the 1890 census were obtained in as little as 2.5 years. Hollerith then founded his own company.
This company later merged with two others to become the Computing Recording Company and then the International Business Machines Corporation, known today as IBM.
IBM then launched the Harvard MARK I, a computer built by Howard Aiken at Harvard University in 1944. This computer was the first electromechanical computer.
In 1946, John Mauchly and Prosper Eckert from the University of Pennsylvania built the first electronic computer, the ENIAC (Electronic Numerical Integrator and Calculator), which was 1000 times larger than the MARK I, weighed 30 tons and had a processing speed of 5000 operations per second.
With the ideas of mathematician John Von Neuman, a new computer called EDVAC (Electronic Discrete Variable Automatic Computer) was produced, 10 times smaller and 100 times faster than ENIAC.
For the first time, a computer called UNIVAC (Universal Automatic Computer) was built that used magnetic tape and could store data. The invention of the transistor in 1947, the development of integrated circuits in the 1960s and the Micro-Chip and Microprocessor in the 1970s paved the way for today’s computers.
COMPUTER GENERATIONS
First Generation Computers (1946-1959)
This generation started with the first computer, the EDVAC, and continued to the transistorized computers. Computers in this generation were circuits made of “vacuum tubes”. These were very large and required constant maintenance. Data and programs were kept in the main memory. They got very hot. Programming was challenging and complicated.
Second Generation Computers (1959-1964)
In this period, vacuum tubes were replaced by “transistors”. The most important innovation of the second-generation computers was the new possibilities they brought to programming. This generation was cheaper, smaller, faster and less energy-consuming than the first generation.
Third Generation Computers (1964-1970)
The most important feature of the third generation of computers is the use of integrated circuits instead of transistors. Using these integrated circuits led to increased speed, reduced size, and lower computer prices. Reliability increased. Computers have attracted more attention than before. Magnetic disks were used for the first time. This made it possible to store as much information as desired.
Fourth Generation Computers (1971- ___ )
Microprocessors started to be used in this period. Computers have increased speed, reduced size and decreased cost. While the size of the first generation computers was the size of a room, today, it has been reduced to the size of a bag. This generation of computers is now being used in homes.
Fifth Generation Computers ( ____ )
It is argued that with the development of technology, this generation will form the products of studies on artificial intelligence.
UNITS OF CAPACITY IN COMPUTING
Computers have their units of measurement, which are measured with these units of measurement.
Units of measurement: Bit, Byte, Kilobyte, Megabyte, Gigabyte, etc.
BIT: Each number “0” and “1” represents one digit of the binary number system. This is called 1 BIT in computer language. Bit comes from the abbreviation of “Binary digit” in English. Computer memory consists of millions of electronic cells representing “0” and “1”. It is the smallest unit of memory size.
Byte: The combination of 8 bits is called 1 byte. Each letter, shape or number seen on the keyboard occupies one byte in memory. The word “GAZİ” takes up 4 bytes of memory.
| SHORT SPELLING | NORMAL SPELLING | SIZE |
| BYTE | 1 Byte | 8 Bit |
| KB | 1 Kilobyte | 1024 byte |
| MB | 1 Megabayt | 1024 KB |
| GB | 1 Gigabayt | 1024 MB |
| TB | 1 Terabayt | 1024 GB |
| PB | 1 Petabayt | 1024 TB |
| EB | 1 Eksabayt | 1024 PB |
| ZB | 1 Zettabayt | 1024 EB |
| YB | 1 Yottabayt | 1024 ZB |
COMPUTER HARDWARE AND SOFTWARE
The physical parts that make up the computer (consisting of the electronic, electrical and mechanical units) are called hardware, and the programs made for the computer are called software. Both hardware and software are needed to use the computer.
Internal Structure of a Computer:
The boards, chips, cables, power supply, etc., inside a computer all make up the internal structure of the computer.
Motherboard (Mainboard)
The motherboard is the board on which the electronic circuits, memory chips, microprocessors and buttons are located to adjust the input/output signals to the peripherals. The motherboard is the most essential part of the computer.
Power supply
The unit provides the electrical power required for the computer to operate. Personal computers (PCs) use between 55 and 200 watts of electrical power.
Image card
The card acts as a bridge between the computer and the monitor. The information generated by the computer is sent to the monitor via the video card. Video cards are divided according to their resolution, colour and speed. It is the card that provides communication between the computer and peripherals.
COMPUTER PERIPHERALS
INPUT UNITS
These units allow information to be transferred directly or read into the computer’s main memory for processing. Input units enable data to be moved from the external environment to the computer environment.
Keyboard
A keyboard is a unit with a keypad composed of numbers, alphabetic characters and special signs that allow the user to enter data into the computer. In general, alphabetic and numeric characters, special characters such as! ^ % & ( ) = { }, etc., and arithmetic characters such as + – * /. Today’s most commonly used keyboards are 101/102 keys, similar to a typewriter.
Mouse
It is a widespread input unit. It is especially effective in Windows programs or ready-made programs. A mouse can have 2 or 3 buttons. When moved on a table, this device moves the cursor on the screen in the same direction as the mouse by means of a ball at its lower level, which rotates in its socket in contact with the table’s surface.
Lighted Pen
The stylus is a pen-like input unit that is very sensitive to light. When the stylus is brought close to the screen, it recognizes the light coming from the display tube, finds the coordinates of that point, and guides the cursor in that direction. It is easy to draw a shape with a stylus or select one of many items. It is a pen that works on the principles of an open-ended photocell used by engineers designing aeroplanes and automobiles.
Joy-Stick
It is an electronic input unit controlled by a lever, mainly used with game programs. A unit designed to move the shapes on the screen in all directions to reflect best the gestures of the user playing the game.
Digitizer Tablet and stylus
It consists of a tablet and its special pen. To enter drawings and graphs, lines and graphic shapes drawn on the tablet with the pen are digitized and transferred to the computer screen. It consists of a tablet up to 3m x 3m in size. The pen is placed on the table surface, and the information at the tip of the pen is transferred to the computer by having the X and Y axes. It is used for map drawing, drawing and modifying engineering and architectural plans, printing and circuit design.
Scanner (Scanner)
It is a device similar to the working principle of a photocopy machine that allows the user to take a picture or text desired by the user into the computer environment.
Barcode Scanners
Nowadays, barcodes, which have started to be used in all areas, are found on the materials sold in supermarkets, pharmacies, stationery, etc. This system is handy in big stores, as stock tracking is relatively easy. Barcode readers read the stock number and operate according to the information from the computer.
Optical Reader (OMR)
They are luminous signal reader units. It is a device that checks whether there is a mark on the papers using optical systems and sends signals according to the situation determined by the computer.
OUTPUT UNITS
Display and printer units are used to receive the results of the information processed in the computer environment.
Screen
The unit displays the data entered from the keyboard and the results produced by the computer. It shows everything when the computer is on. The screen converts the sent signals into an image the eye can see. The screen is both an input and output unit.
Printers
It transfers information or text entered into the computer onto paper.
Printers are named according to the writing technology they use.
– Dot Matrix
– Inkjet
– Laser
Dot matrix printers (Dot matrix)
They are the cheapest and, therefore, the most commonly used printers. In these printers, the print head consists of tiny needles arranged in a matrix. Depending on the signals from the computer, the relevant needle is activated and printed on the inked ribbon. The ink on the ribbon presses the paper, transferring the image to the paper. The more needles in the printer head, the better the print quality. Generally, matrices with 24 needles are used. The average image quality in 9-needle printers is 216x 240 dpi (dot per inch).
The most significant disadvantage of dot matrix printers is the low print quality and speed. Printing speed is measured by the number of characters printed per second. This is called CPS (Character Per Second). A dot matrix printer with 10 CPS can print 10 characters per second. Dot matrix printers can also print in colour.
Daisy wheel printers
It is the type of printer most similar to a typewriter in terms of printing technique. The printer can print all the shapes on a print head that looks like a daisy.
Inkjet printers (Inkjet printers)
It is a printer whose printing speed and quality are much better than dot matrix printers and whose use is becoming more widespread daily. The writing heads of inkjet printers consist of a matrix of holes. Behind this writing head is an ink reservoir (cartridge). The ink in this reservoir is sprayed onto the paper according to the signals coming from the computer. The printing speed of inkjet printers is measured by the number of lines printed per minute. This is called LPM (Line Per Minute). Inkjet printers can also print in colour. However, this requires a colour cartridge (ink reservoir).
Laser printers
They are today’s best and fastest types of printers. Laser printers are similar to computer-controlled photocopiers. The image of the page to be printed is created in the printer’s memory, and toner (a type of solid ink) is printed on the paper in the light of data from the computer. In laser printers, print quality is measured in pages per minute (PPM). The only disadvantage of laser printers, which can print very fast, in good quality and without noise, is their high price.
Plotters
These printers can make graphic drawings by moving more than one pen on the paper’s X and Y axes. There are two types of plotters. “Drum Plotters” are units that generally use continuous forms, where both the paper can move back and forth, and the pens can move on the paper.
CENTRAL PROCESSING UNIT (CPU)
The most important part of the computer, the Central Processing Unit (CPU), can be considered an electronic brain. The CPU, capable of high-speed processing, controls all units and commands what to do and how to do it. The CPU is also known as a microprocessor. All information on it is erased when the power is cut.
ROM (READ-ONLY MEMORY)
ROM is a non-volatile memory that contains some basic information in a computer. The manufacturer programs them. ROM stores the computer’s system information. The contents of ROM are unaffected by power failure, as with RAM. ROM Read-Only Memory A read-only memory is obtained by initializing English words. It is not possible to change or erase the information in ROM. However, programmable ROMs and erasable ROMs were later produced. Programmable ROMs are called PROMs, and erasable ROMs are called EPROMs. However, erasing or programming these ROM types is a speciality.
RAM (RANDOM ACCESS MEMORY)
RAM, Random Access Memory, is a random access memory derived from the initials of the English word Random Access Memory. It is the main memory of the computer. The information on RAM is destroyed when the computer is turned off, or there is a power failure. The higher the capacity of RAM, the faster the computer’s speed. Access to information in RAM is much quicker than on a disk or floppy disk drive.
CACHE MEMORY
Since RAM cannot keep up with the CPU’s speed, the buffer memory helps to transfer information between the CPU and RAM.
AUXILIARY MEMORY UNITS
Auxiliary memory units are used as input and output, where they are printed to store information and reuse it when necessary.
Hard Disk (Harddisk)
A stationary auxiliary memory unit used to store more information is housed in a sealed box inside the main chassis.
CD-ROM
A disk unit on which information loaded with recorders, such as images or sound recordings, can only be read. CD-ROMs (Compact-Disc-Read Only Memory) are the same as music compact disks. A CD-ROM stores about 650 MB of information, as much as 451 floppy disks can store. A CD-ROM drive is a device that reads the digital data on compact disks. The speed at which CD-ROM drives read information is expressed in multiples of 150 kb/second. For example, a CD-ROM drive with a speed of 20X can read 3000 KB of information per second.
CD-ROM drives read the information on the disk with the help of laser light. The disk rotating inside the drive has tiny pits and peaks. These areas reflect the laser light differently and are detected and converted into numbers. The faster the disk spins, the quicker the information can be read.
CD Burners
They are devices that allow us to record information on CDs. Today, CD burners can record on two types of media: CD-R (writable CD) and CD-RW (rewritable CD) disks. The data written once on a CD-R disk cannot be erased, meaning you cannot record any more information once you have filled its capacity of 650 Mbytes. On the other hand, CD-RW disks can be used over and over again (about 1000 times) because the information that can be recorded on these disks can be erased. CD-Rs are made by burning tiny holes in the disk’s surface with a powerful laser light while writing information. CD-RWs do not have such holes. The disk has a layer covered with a unique chemical substance. When a certain amount of laser light is applied, this material crystallizes and reflects more light. If necessary, it can be restored to its original state using another laser light.
DVD
DVD is a newly developed high-capacity disk standard. DVDs will be the same size as CD-ROM disks but with a data storage capacity of 4.7 Gbytes (and, in the future, 17 Gbytes).
Modem
Modems convert digital signals into analogue signals that can be transferred over telephone wires. They have both a transmitting and receiving function. At the receiving end, the computer modem converts the voice signals sent by the other station over the telephone line into bit signals and transfers them to the computer. The computer modem at the transmitter is transmitted to the other station via a telephone line that will convert the bit signals, which are the computer outputs of the local station, into audio signals.
Voice Card
A sound card is an expansion card that allows the computer to record and play sounds. The sound card performs these operations numerically. When recording, it converts the sound into a series of numbers, and when playing, it converts those numbers back into sound. Another function of sound cards is to produce music. It does this with the help of a system called MIDI, which processes musical notes. The sound card is responsible for converting the notes into music.
Digital Cameras
DIGITAL cameras are devices that do the work of cameras digitally and transfer the pictures to the computer environment.
SOFTWARE
These are programs created to make our computers do specific tasks. In other words, they are programs that are not hardware but activate all the hardware. Without software, we cannot make our computers do anything. Software is implemented with programming languages. We can examine software in three groups;
– Application Programs
– Programming Languages
– Programming Operating System
Application Programs
These are programs written in one or more programming languages for a specific application (customer tracking, graphic drawing, game, etc.). These programs are made by good programmers or software companies and released to the market as package programs.
Programming Languages
Software is used to create applications and system software. All programs are written in programming languages. Like computers, programming languages have been developed through various processes. Programming languages usually consist of words chosen or coded from English words.
Operating System Software
Software that enables communication between the computer and the user. Operating systems are also written in one of the programming languages. The operating system is installed on the hard disk. (This event is called BOOT.) Thus, the operating system keeps information about files and directories. The computer hardware is prepared for any task with the operating system.
