The characteristics of these devices from generation to generation and their classification according to sizes, functions and uses shall also be discussed. DEFINITION OF KEY TERMS Evolution: Evolution is a gradual development that occurs in a particular place or thing. Technology: This is the use of mechanical arts and applied science. Technology here refers to systems, methods of organization and techniques. Computer:A computer is a programmable mechanical device that accepts information or inputs, stores and manipulates data and brings out the result or output in numerical format.COMPONENTS OF A COMPUTER SYSTEM A general purpose computer has four major components namely: arithmetic and logic unit (ALU), control unit, memory and input/output devices. These parts are interconnected by buses often made of groups of wires.
ARITHMETIC AND LOGIC UNIT (ALU) This unit carries out arithmetic and logic operations. According to Stokes (2007), the set of arithmetic operations that a particular arithmetic and logic unit supports may be limited to adding and subtracting or might include multiplying or dividing functions ( sine, cosine, etc) and square roots.While others represent real numbers with the use of floating point, some can only operate on whole numbers (integers) albeit, with limited precision. Arithmetic operation could be carried out by any programmed computer. Logic operation can be useful both for creating complicated conditional statements and processing Boolean logic. THE CONTROL UNIT The control unit which is often called a control system or central controller, manages the computer’s various components. It reads and interprets (decodes) the program instructions, transforming them into a series of control signals which activate other parts of the computer.
In order to improve performance, the control system in advanced computer may change the order of some instructions. FUNCTION OF THE CONTROL SYSTEM It reads the codes for the next instruction from the cell indicated by the program counters. It decodes the numerical code for the instruction into a set of commands or signals for each of the other systems. Whatever data the instruction requires from cells in memory are read by the control system. Necessary data to an arithmetic and logic unit or register is also provided by the control system.If the instruction requires an ALU or specialized hardware to complete, it instructs the hardware to perform the requested operation. It writes the results from the ALU back to a memory location or to a register or perhaps an output device.
It could be observed that the sequence of operations gone through by the control unit to process an instruction is in itself like a short computer program. MEMORY The memory of a computer is seen as a list of cells into which numbers can be placed or read. Each cell has a numbered address and can store a single number.Anything such as numbers, letters can be represented by the information stored into the memory with equal ease. Software gives significance to what the memory sees as series of numbers. In almost all modern computers, each memory cell is set up to store binary numbers in gaps of 8bits or bytes. Each byte representing 256 different numbers (Stokes 2007).
Several consecutive numbers may be used to store larger numbers. Computer memory is of two types or principal varieties: The Random Access Memory (RAM) and Read Only Memory (ROM).Random Access Memory according to Inyang and Umoh (2003), is a part of primary memory that holds the programs being executed and the data to be worked upon. RAM also stores the result of a processed data, waiting to be transferred to output device or secondary storage device. It is a temporary memory and the content of RAM is erased when a computer is turned off and data stored in it can instantly be accessed. The storage of RAM is expressed in megabytes and its capacity or size limited. An area of RAM set aside for storage of most frequently accessed information is the CACHE memory.
It is a temporary high speed data holding area between the memory and the central processing unit. RAM has four parts: the conventional memory which consist of the first 640KB of RAM, used by operating system and device drivers; Upper Memory Bound (UMB) located between 640KB and 1MB of RAM, used by device drivers: extended memory (XMS) which include direct access memory above 1MB; and Expended memory: a special part of ram that is up to 32MB and exists outside the conventional memory. Read only memory (ROM) is preloaded with data and software that never changes, so the central processing unit (CPU) can only read it.ROM is typically used to store the computer’s initial start up instructions. It retains its data indefinitely. In a personal computer (PC), ROM contains a specialized program called the BIOS that orchestrates loading the computer’s operating system from the hard disc drive into RAM whenever the computer is turn on or reset. All of the required software may be stored in ROM in embedded computers which frequently do not have disc drives.
Software stored in ROM is referred to as firmware because it is more like hardware than software. INPUT/OUTPUT DEVICEMeans by which information between the computer and outside world is exchanged is known as input/output. Peripheral includes input devices like keyboard and mouse, and output devices such as the display and printer. Hard disc drives, floppy disc drives and optical disc drives serve as both input and output devices. HISTORY OF COMPUTER Computer technology has changed today world to a global village. Since the field of computer is a vast sea, there are many options and benefits one can get from it. Internet is constant and rapidly growing source of information.
People can get information or piece of required knowledge from any part of the world by just a few clicks on the websites. There is a rise in the need of more websites and knowledgeable sources as information is much easier to access. The early men counted by means of matching one set of object with another set. The history of modern computer begins with two separate technologies: automated calculation and programmability. The earliest known computing device was called ABACUS. It is the first counting device that was developed about 500BC (Umoh and Inyang, 2003).It is made up of wood and beads.
It has a role of any number of parallel wires, rods or grooves on or in slide of small beads or blocks. Strung beads which have different values were manually used to operate abacus. Bars were used in dividing the Abacus into two parts perpendicular to the rods. Bits moved in active position towards the bars and the ones towards the frame are ignored. Each bar signifies digits and least significant digits were on the right. Abacus was used in calculating (i. e.
adding, subtracting, multiplying and dividing) numbers by moving the bit complex.In the 9th century, the Persian Mathematician Abu, Abdullah Muhammad Bin Musa Al-Khwarizni developed the concept of a written process followed to achieve some goals, and published a book on the subject that gave us its modern name Algorithm. In 1623, Wilhelm Schikard, a German Scientist invented a machine that used eleven complete and six incomplete sprocketed wheels that could add and with the aid of logarithm tables, multiply and divide. Many inventions have taken several centuries to develop into the modern forms and modern inventions are rarely the product of a single inventor’s effort.Many people each added a small contribution towards the development of the bits and pieces of a computer (including the software). Each person in this work contributed a part towards the development of computers. In 1642, a 19year old French boy, a philosopher and mathematician Blaise Pascal invented a mechanical adding machine called a Mechanical Calculator.
It is like a modern desk calculator and contains numbers of wheel and uses gear system to perform arithmetic operations. Computations are carried out by a process of integer counting.In 1801, Punch cards were invented by a French Weaver called Joseph Marie Jacquard. These Punch Cards allowed his loom to automatically weave intricate patterns. Different parts were used in storing different patterns of holes that produced different designs. Punch Cards are used in processing information in computers. The fusion of automatic calculation with programmability produced the first recognized computers.
Charles Babbage, British Mathematician and inventor, invented mechanical computing machine – Babbage’s Analytical Engine.In 1820, it carried out complex arithmetic operations and made decisions based on its own computations. It was self-controlled and had two important parts which are the storage unit with memory device and arithmetic unit known as the Mill. It was the world’s first digital computer. Babbage’s contributed the idea of conditional transfer which gave way to comparison of quantities and modification of programs. The idea of a sequence of punch cards to produce a more flexible design was borrowed from the Jacquard’s pattern weaving loom. It performed functions like additions, subtraction, division and multiplication.