Oct. 3rd, 2007

What is a Computer?

A computer is a machine that can be programmed to accept data (input), process it into useful information (output), and store it in a secondary storage device for safekeeping of later reuse. The processing of input to output is directed by software but performed by the hardware.

A computer system has three main components: hardware, software, and people. The equipment associated with a computer system is called hardware. A set of instructions called software tells the computer what to do. People, however, are the most important component of a computer system. People use the power of the computer for some purpose.

Software is also referred to as programs. To be more specific, a program is a set of step-by-step instructions that directs the computer to do the required tasks and produce the desired results. A computer programmer is a person who writes programs. Users are people who purchase and use computer software. In business, users are often called end-users because they are at the end of the “computer line”,” actually making use of the computer’s capabilities.

The Five Generations of Computers

The history of computer development is often referred to in reference to the different generations of computing devices. Each generation of computer is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices.
Bilgisayarların her bir kuşağı, bilgisayarların işleyişini değiştiren, gittikçe küçülen, ucuzlayan, daha güçlü, verimli ve daha güvenilir cihazlar olmasıyla sonuçlanan büyük teknolojik gelişmelerle tanımlanır.

First Generation - 1940-1956: Vacuum Tubes

The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.

First generation computers relied on machine language to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.

lThe UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.

Assignment-1 Due: Oct.10th, 2007

Second Generation - 1956-1963: Transistors

Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 50s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.

Second-generation computers moved from cryptic binary machine language to symbolic, or assembly languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.

Third Generation - 1964-1971: Integrated Circuits

The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.

Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.