• Super Computers • Mainframe Computers. • Minicomputers. • Microcomputers. • Special Purpose Computers. • Lap tops • Palm tops • Work Stations • Servers
Comparison of Computers Computers have become • Faster (more powerful and more memory), • Cheaper (cost less) and • Smaller in size Supercomputers • Sophisticated, expensive computers, Provide processing speeds, many times that of powerful workstations. • Particularly used in the simulation and modeling of complex systems. e.g. weather, chemical processes, the US economy, motion of galaxy
Mainframe Computers • A multi-user computer designed to meet the computing needs of a large organization. • Originally the term referred to the metal cabinet housing the CPU. • Generally refers to computers of the 1950s and 1960s. • Can process a number of applications concurrently. • Used by large organisations to handle millions of transactions. • Usually housed in specially wired air-conditioned rooms.
Minicomputers • Scaled down mainframe. (refrigerator-size) • Designed to meet the computing needs of a department or small company. Typically 4-100 users. Can support a number of concurrent applications.
Microcomputers • Appeared mid-to-late 70s. E.g. Apple II, Sinclair Spectrum, Commodore PET • Portable models now available • Small computers that can fit on a desktop or briefcase. • There are two types • Personal Computers (PC) • Workstations
Personal Computer (PC) • Desktop or portable (laptop, notebook, palmtop). • Used in most organisations and at homes. • Commonly used for easy-to-use programs such as word processing, spreadsheets. Workstations • Connected to large computer system. • Designed to work with large or complex applications. .e.g. drafting, engineering design, 3D-graphical models
Computer is a man made programmable electronic machine which can store, retrieve and process data into information according to the instructions given.
Data + Instructions – Information
What is Data?
Raw facts that are to be processed
What is Information?
Processed Data with meaning
Characteristics of the Computer
Comparative to human
Advantages
1Speed
2Accuracy GIGOGarbage in garbage out
3Diligencefree from tiredness
4Versatility could perform different tasks
5Power of remembering
Disadvantages
No IQ
No feelings
History of Computer.
Mechanical Age
•Abacus – First man made computing deviceis ABACUS It is a calculating device (3000 BC)Small beads are arranged on vertical rods
•Von Leibnitz made improvements in the Pascals machine in 1674.Addition, Subtraction, Multiplication, Division could be done
•Joseph Jacquard introduced the punch card system for the weaving industry(1800)
•Charles Babbage (Fatherof Computers) English mathematician in 19th century Using the punch card system he invented the analytical engine. This was not successfulas the mathematics knowledge at that time was not adequate. This machine could store 1000, 50 digit numbers for calculations & decisions.He called this the analyticalengine (1830s)
He also invented the Difference Engine
.Ada Love lace-World's first programmer (1800s)
Hollerith - tabulating machine (1890s)He introduced a system to process census data in United States in 1890 using punched card system
•The code developed by Hollerinthis called the Hollerinth code
ELECTRONIC AGE
1900-1945
Howard Aikenusing Babbages concept invented MARK I a calculator in 1944.MARK I used a typewriter as the input & punched cards as the
output.Weighed 15 tons.
1 st generation(1946)
ENIAC (Electronic Numerical Integrator & Computer) was the first electronic digital computer built in 1946. ENIAC used the vacuum Tube technology.
In 1950 Remington Rand manufactured the
UNIVAC 1 (Universal Automatic Calculator) first machine to use magnetic medium for input and output.
In 1957 IBM (International Business Machine) Corporation developed IBM 704 which could perform 100000 calculations per second.
2 nd generation (1950)
Late 1950 transistors were invented and replaced vacuum tubes.It could perform 200,000 – 250,000 calculations per second.
Tapes were used for output.
3 rd generation ( 1959 1965 )
Integrated circuits replaced the transistors.Magnetic discs were used for storing.
4 th generation (1971)
Integratcd circuits were coupled and formed LSI (Large Scale Integration) and VLSI ( Very Large Scale Integration) which formed microchips.Multi-programming and virtual storage memory were introduced.
5th generation (1980)
These computers operated at a speed of3 to 5 million calculations per second.