computer

What is a computer?

•      Wikipedia definition says it is a programmable machine that receives input, stores and manipulates data, and provides output in a useful format.

•      To compute means to calculate  so a computer is something that calculates

•      Over the years computers have grown into various forms and sizes to suit the various needs of our day to day lives

•      So computers are classified into the following groups

•      Micro computers

•      Mini computers

•      Personal computers

•      Mainframe computers

•      Supercomputers

Micro computers:

•      A microcomputer is a computing device. The invention of microprocessor single chip central processing unit gave birth to Microcomputer.

Descpription:

•      Microcomputers are designed to serve one user at a time they can often be modified with software or hardware to concurrently serve more than one user.

•      A microcomputer comes equipped with at least one type of data storage

•      A microprocessors and semiconductor memory became less expensive, microcomputers in turn grew cheaper and easier to use.

History:

•      The term "Microcomputer" came into popular use after the introduction of the minicomputer, Isaac Asimov used the term microcomputer as early as 1956.

•      1970:

      The 1970s not only saw the birth of the microchip, but the sale of millions of micro computer kits to the general public.  

•      1980:

      The 1980s saw the microcomputer re-branded as the personal computer by (IBM).

     This is also when assembly language began to be replaced by higher level languages.

•      2000 and beyond:

      Hardware and software for micro computers continues to advance at unprecedented rates.

Facts:

•      They are the most popular form of computers

•      A large number of computer makers packaged microcomputers for use in small business applications.

•      This allowed businesses unable to afford for buying minicomputer.

•      The increasing availability and power of micro computers for personal use attracted the attention of more software developers.

Mini computers:

•      DEFNITION:A minicomputer, a term no longer much used, is a computer of a size intermediate between a microcomputer and a mainframe. Typically, minicomputers have been stand-alone computers (computer systems with attached terminals and other devices) sold to small and mid-size businesses for general business applications and to large enterprises for department-level operations

History:

•      Mini Computers: These are powerful computer. These computers come into existence in 1960s at that time mainframe computer was very costly. Mini computers were available in cheap prices, so users start using it.

•      minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems (mainframe computers) and the smallest single-user systems (microcomputers or personal computers).

The Minicomputer's Industrial Impact and Heritage

Computer companies first built minicomputers:

•      DEC

•      DATA GENERAL

•      HEWLETT PACKARD(HP)

•      In the software content:

     Relatively simple OS for microcomputers were usually improved by minicomputers OS

§  UNIX was originally minicomputer OS.

§   In recent years, the minicomputer has evolved into the "mid-range server" and is part of a network.  

§  IBM’s As/400 is a good example.

Uses:

•      Minicomputer is a relative term. These antiquated machines were developed in the 1960's, and used heavily into the 1980's, at which point they were replaced by personal computers. Minicomputers were compact alternatives to the large, room-sized computers of the same era. Costing somewhere in the neighborhood of $20,000 through the 60's and 70's, minicomputers had a limited range of functionality, and were used for three primary purposes: process control, data management, and communications

Personal computer:

Defenition:

•      A personal computer (PC) is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user with no intervening computer operator.

History:

•      A personal computer is an inexpensive computer, originally designed to be used by only one person at a time, and which is IBM PC compatible

•      The earliest known use of the term was in New Scientist magazine in 1964

•      The first generation of microcomputers that started to appear in the 1970s (see home computers) were less powerful and in some ways less versatile than business computers of the day (but in other ways more versatile, in terms of built-in sound and graphics capabilities), and were generally used by computer enthusiasts for learning to program, for running simple office/productivity applications, for electronics interfacing, and/or games, as well as for accessing BBS's, general online services such as CompuServe, The Source, or Genie, or platform-specific services such as Quantum Link (US) or Compunet (UK).

•      It was the launch of the VisiCalc spreadsheet, initially for the Apple II and later for the Atari 8-bit family, Commodore PET, and IBM PC that became the "killer app" that turned the microcomputer into a business tool. Later, Lotus 1-2-3, a combined spreadsheet (partly based on VisiCalc), presentation graphics, and simple database application, became the PCs own killer app. Good word processor programs also appeared for many home computers. The low cost of personal computers led to great popularity in the home and business markets during the 1980s. In 1982, Time magazine named the personal computer its Man of the Year.

•      During the 1990s, the power of personal computers increased radically, blurring the formerly sharp distinction between personal computers and multi-user computers such as mainframes. Today higher-end computers often distinguish themselves from personal computers by greater reliability or greater ability to multitask, rather than by straight CPU power.

Types:

•      Work station

•      Desktop computer

•      Single unit pc

•      Net top

•      Laptop

•      Net book

•      Tablet pc

•      Ultra mobile pc (UMPC)

•      Home theater pc (HTPC)

•      Pocket pc

Main frame computers:

•      Mainframes are the powerful computers that can process billions of instructions per second and capable of accessing billions of data.

•                       . The name comes from the way the machine is built up: all units  were hung into a frame and hence the name Mainframe computer evolved.

•                  And because of the sheer development costs, mainframes are typically manufactured by large companies such as IBM, Amdahl, Hitachi.

•                They are usually slower, less powerful and less expensive than supercomputers. A technique that allows many people at terminals, to access the same computer at one time is called time sharing.

•               Mainframes are used by banks and many business to update inventory etc.

•               Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.

•              Mainframe computers are used in large organizations where many users need access to shared data and programs.

•              Mainframes are also used as e-commerce servers, handling transactions over the Internet.

•              This computer is commonly used in big hospitals, air line reservations companies, and many other huge companies prefer mainframe because of its capability of retrieving data on a huge basis.

What classifies the computer as a mainframe?

•      A mainframe has 1 to 16 CPU's (modern machines more)

•      Memory ranges over 8 Gigabyte on line RAM

•      Its processing power ranges from 80 over 550 Mips

•      It has often different cabinets for

–     Storage,I/O,RAM

•      Separate processes (program) for

–     task management

–     program management

–     job management

–     serialization

–     catalogs

–     inter address space

–     communication

Operating system for mainframes:

•       Linux

•       Unix

•       Vms        

Super computer:

•      The Wikipedia definition: a supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation

•      The term supercomputer itself is rather fluid, and today's supercomputer tends to become tomorrow's ordinary computer

History:

•      Early machines were simply very fast scalar processors

•      1970s most supercomputers were dedicated to running a vector processor

•      The early and mid-1980s machines with a number of vector processors working in parallel with the number of processors ranging from four to sixteen.

•      later 1980s and 1990s: vector processors to massive parallel processing systems with thousands of ordinary CPUs

•      Today, parallel designs are based on "off the shelf" server-class microprocessors, such as the PowerPC, Opteron, or Xeon, and coprocessors like NVIDIA Tesla GPGPUs, AMD GPUs, IBM Cell, FPGAs

About:

Supercomputers make use of the following technologies

•      Vector processing

•      Liquid cooling

•      Non-Uniform Memory Access (NUMA)

•      Striped disks (RAID)

•      Parallel file systems

•      Operating systems: Supercomputers today most often use variants of Linux

•      Programming: The base language of supercomputer code is, in general, Fortran or C

•      As of October 2010, the Tianhe-I located in China Is the fastest in the world

Uses:

Supercomputers are used for highly calculation intensive tasks like

•       quantum physics

•       weather forecasting, climate research, 

•      molecular modelling(computing the structures and properties of chemical compounds, biological macromolecules, polymers, and crystals),

•      physical simulations (simulation of airplanes in wind tunnels, detonation of nuclear weapons, and research into nuclear fusion).