Types of Computer

• Applications of information and communication technologies are explained in lecture 2.

Types of Computer

• According to functionality, computers can be divided into three types: analog, digital, and hybrid.

Analog Computer

• Analog computers use continuously changeable aspects of physical phenomena to model problems.
• Physical phenomena used include electrical, mechanical, or hydraulic quantities.
• "Continuity" of associated quantity like distance traveled by a clock hand tells time.
• Analog computers measures and answer questions about physical quantities.
• Analog input isn't a number but a physical quantity like temperature, pressure, speed, or velocity.
• Analog computers were used in World War II and the Korean War and were common in science and industry before digital computers.
• Examples: Thermometers and analog clocks.

Digital Computer

• Digital computers perform calculations and logical operations with digits, usually using the binary system ("0" and "1").
• Digital computers solve problems by processing discrete information.
• Digital computer count and answer questions by the method of "HOW Many".
• Digital computers represent input as numbers for logical and arithmetic operations.
• Digital computers manipulate combinations of binary digits.
• Digital computers are used for mathematical calculations, organizing/analyzing data, and controlling industrial processes.
• Examples include, IBM PCs, Apple Macintosh, and calculators.

Hybrid Computer

• Hybrid computers processes both analog and digital data.
• Hybrid computers take analog signals, convert them to digital form, and process them digitally.
• Hybrid machines are generally used in scientific applications or industrial processes.
• Examples: radar.
• Hybrid computers can be used in hospitals to measure a patient's heartbeat.

Classification of Computers

• Computers can also be divided by size capacity into four classifications: super, mainframe, mini, and micro.

Super Computers

• Supercomputers lead the world in processing capacity, particularly the speed of calculation.
• Supercomputers handle gigantic amounts of scientific computation.
• Supercomputers are about 50,000 times faster than micro-computers.
• Supercomputers are used for engineering and scientific problem analysis, computer graphics, and special effects.
• Supercomputers can cost as much as $20 million.
• Supercomputers contain number of CPUs which operate in parallel to make it faster.
• Supercomputers are also called grandfather computers.
• Supercomputers are used in areas like: defense, weather forecasting, scientific research, drug discoveries, and Hollywood movies.
• Supercomputer examples include: CRAY X1, CRAY T90, and Control Data Cyber 205.

Mainframe Computers

• Mainframe computers are smaller and less powerful than supercomputers
• Mainframe computers can support hundreds/thousands of users.
• Mainframe computers used in large organizations for critical applications that need bulk data processing.
• Mainframes are large, fast computers typically housed in a controlled environment.
• Mainframes are in multi-user environments that service more than 100 terminals at a time.
• Terminals look like microcomputers and are the access points to mainframe services for users to enter and retrieve data.
• ENIAC (Electronic Numerical Integrator and Calculator) and UNIVAC (Universal Automatic Computer) were mainframe computers.

Mini Computers

• Mini computers are smallest computer designed specifically for the multi-user environment.
• Mini computers allow several persons to use the machine at the same time.
• Before the late 60's most computers produced were mainframe computers and they were very expensive.
• The large price of mainframes limited its buyers to only the largest companies.
• Minicomputers are smaller, more affordable versions of mainframes.
• Minicomputers have smaller storage capacities and serve fewer terminals than mainframes.
• Computers servicing more than 100 terminals are no longer called minicomputers.
• The main difference between mainframes and minicomputers is the number of terminals they can service.

Micro Computers

• Micro computers are personal computers designed to meet the computer needs of an individual and provides a wide variety of computing applications.
• Computing applications could include word processing, photo editing, email, and internet.
• Main difference between microcomputers and minicomputers and mainframes is that micros are generally single-user but multi tasking machine.
• Personal Computers (PC) occupy physically small amounts of space.
• Micro computers use low power consumption.
• Examples of micro computers are desktop, laptop, and handheld computers.

Workstations

• Workstations are similar to desktop PCs but unlike desktops, they have high end processing speed for specific software.
• Workstations are used for Graphic Designing, Special effects for movies, and CAD Applications.

Embedded Computers

• Embedded computers are special-purpose computers that function as components in a larger product.

Servers

• A server is a large shared computer
• Servers have several times the power and memory of a workstation
• The operating system and hardware of servers have been optimised.
• A server may act as one or more of functions like:
  • compute server: to run programs
  • file server: to store files centrally
  • mail server: to route mail messages
  • web server: to store web files etc
  • Print server: to print the document
  • Proxy server: to provide internet access.

Early History of Computing

• Abacus: an early device to record numeric values (not considered computer).
• Blaise Pascal: Invented a wheel-based mechanical device to add, subtract, divide, and multiply.
• Joseph Jacquard: created Jacquard's Loom, the punched card.
• Charles Babbage: created the Analytical Engine.

Blaise Pascal

• In 1642, Frenchman Blaise Pascal invented a new kind of computing device.
• This computing device used wheels instead of beads, each numbered '0' to '9'.
• Pascal's machine, Pascaline, could add up to 999999.99 and subtract.

Gottfried Leibnitz

• Leibnitz improved Pascal's adding machine to also perform multiplication, division, and calculate square roots.

Joseph Jacquard

• In the late 1700s in France, Joseph Jacquard invented a way to control the pattern on a weaving loom to make fabric using punched cards.
• Jacquard's machine didn't count anything. therefore it wasn't a computer or even a computing device, but led to many other computing.

Charles Babbage's Difference Engine

• Babbage is the father of modern computing because he designed a general purpose computing device.
• In 1822, Babbage began design and build build a small working model of an automatic mechanical calculating machine,"difference engine".
• It could find the first 30 prime numbers in two and a half minutes.
• In 1833, Babbage had a construction idea what today would be described as a general-purpose, fully program-controlled, automatic mechanical digital computer.
• Babbage called his machine an "analytical engine".
• Babbage designed what is now known as computers:
  • an input device - punched card reader an
  • output device - a typewriter
  • memory - rods which when rotated into position "stored" a number
  • control unit – punched cards with instructions encoded as
• Babbage's analytical engine contained all the basic elements of an automatic computer: storage, working memory, a system for moving between the two, an input device and an output device.
• Babbage lacked funding to build the machine so Babbage's computer was never completed.

Generations of Electronic Computers.

• First Generation Computers (1940-1956)
• Second Generation Computers (1956-1963)
• Third Generation Computers (1964-1971)
• Fourth Generation Computers (1971-Present)
• Fifth Generation Computers(Present and Beyond)

First Generation Computers (1940-1956)

• First computers used vacuum tubes for circuitry and magnetic drums for memory with computers often being enormous.
• First computers were very expensive to operate and had generated a lot of heat, creating cause of malfunctions.
• First generation computers relied on machine language
• Input was based on punched cards and paper tape, and output was displayed on printouts.
• The UNIVAC and ENIAC computers are examples of first-generation computing devices.

First Generation Hardware

• Vacuum tubes: glass tubes with circuits inside of them that have no air inside of them, which protects the circuitry.
• Magnetic Drum: Memory device that rotated under a read/write head
• Card Readers and Magnetic Tape Drives also used .

Second Generation Computers (1956-1963)

• Transistors replaced vacuum tubes and were invented in 1948 but did not see widespread use in computers until the late 1950s.
• They were for superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable .
• They were 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.
• 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.

Second Generation Hardware (1956-1963)

• Transistor Replaced vacuum tube, fast, small, durable, cheap
• Magnetic Core Replaced magnetic drums, information available instantly
• Magnetic Disks Replaced magnetic tape, data can be accessed directly

Third Generation Computers (1964-1971)

• 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.
• The operating system 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.

Third Generation Hardware (1964-1971)

• Integrated Circuits: Transistors, resistors, and capacitors integrated together into a single "chip"
  • Replaced circuit boards, smaller, cheaper, faster, more reliable
• Transistors are now used for memory construction.
• Terminal is an input/output device with a keyboard and screen

Fourth Generation Computers (1971-Present)

• Fourth generation computers used the microprocessor as thousands of integrated circuits were built onto a single silicon chip.
• The first generation filled an entire room could now fit in the palm of the hand.
• The Intel 4004 chip, developed in 1971, located all the components of the computer-from the central processing unit and memory to input/output controls- on a single chip.
• In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh.
• The use of Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.
• As these small used were able to be linked to form networks, which eventually led to the development of the Internet.

Fourth Generation Hardware (1971-?)

• Large-scale Integration and Great advances in chip technology
• PCs, the Commercial Market and Workstations were developed as Personal and more companies like Apple, Sun, Dell.
• Laptops- Everyone has his/her own portable computer
• Parallel Computing- Computers rely on interconnected central processing and/or memory units that increase processing speed
• Networking Ethernet connects small computers to share resources
• A Microchip is a Very Large Scale Integrated Circuit (VLSIC)
  • Microchips are built using Transistors, resistors, and capacitors
  • The 4004 had 2,250 transistors
  • The Pentium IV has 42 MILLION transistors using Each transistor 0.13 microns (10-6 meters)

Fifth Generation Computers (Present and Beyond)

• Fifth-generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today.
• The use of parallel processing and superconductors is helping to make artificial intelligence a reality.
• Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come.
• The goal of fifth-generation computing is to develop devices that respond to natural language input capable of learning and self-organization.

• First Generation Software (1941-1956)- Machine Language- Computer programs written in binary (1s and 0s. Assembly Languages and Translators- Programs written using mnemonics.
• Second Generation Software (1956-63): High-level Languages, English-like statements made programming easier like : Fortran, COBOL, Lisp
• Third Generation Software (1964-71); Systems Software Utility programs: Language translators, Operating system, which decides which programs to run and when, Separation between Users and Hardware
• Fourth Generation Software (1971-1989); Structured Programming like Pasca, IC and C++. Developed New Application Software for Users such as Spreadsheets and Word processors.
• Fith generation Software (1990- Present); Microsoft, Windows and Object-Oriented Design based such as Java and C# and the World Wilde Web