Hardware

Computer hardware is defined as all the physical components of the machine itself. The basic hardware if the computer includes the electronic circuits, microchips, processors and the motherboard inside the computer housing.

A computer is a machine that uses electronic components and instructions to the components to perform calculations and repetitive and complex procedures.

Computer Hardware Fundamentals

Motherboard a thin flat sheet made of firm, nonconducting material on which the internal components- printed circuits, chips, slots and so on- of the computer mounted. The motherboard is made up of a dielectric or nonconducting plastic material, and the electric conduction are etched or soldered onto the bottom of the board.

Four Basic Components of the computer:

Central processing Unit

The CPU is the “brains” of the computer. It consists of at least one arithmetic and logic unit, a control unit, and memory. The arithmetic and logic units control the mathematical functions such as addition and subtraction and functions that test logic conditions. The control unit carries out machine language functions called fetch, execute, decode, and store. Memory includes the locations of the computer’s internal or main working storage. Memory consists of registers, random access memory(RAM), which is the main storage area in which the computer places the programs and data it is working on and the cache(a small memory storage area holding the recently accessed data).

Memory

• Read Only Memory. ROM is a form of permanent storage. This means that data and programs can only be read by the computer, and cannot be erased or altered. ROM generally contains the programs, called firmware, used by the control unit of the CPU to oversee the computer functions.

• Random Access Memory. RAM refers to the working memory used for primary storage. It is volatile(changeable) and used as temporary storage. RAM can be accessed, used, changes and written on repeatedly. It contains data and instructions that are stored and processed by computer programs called application programs; RAM is the work area available to the CPU for all the processing applications.

Input and Output

To do work, the computer must have a way of receiving commands and data fro the outside and a way of reporting out its work. The motherboard has slots and circuit boards that allow the CPU to communicate with the outside world. Input and  output devices are wired to a controller that is plugged into the slots or circuit board of the computer.

Input Devices. These allow the computer to receive information from the outside world. the most common input devices are the keyboard and mouse. Other commonly seen in the nursing stations include the touch screen, light pen, voice and scanner.

A touch screen is actually both an input and output device combined. Electronic allow the computer to sense when a particular part of the screen is pressed or touched.

A light pen is a device attached to the computer that has special software that allows the computer to sense when the light pen is focused on a particular part of the screen.

Output Devices. These allow the computer to report its result to the external world. Output can be in the form of text, data files, sound, graphics or signals to other devices. The two most obvious output devices are the monitor and printer.

Storage media

Storage includes the main memory but also the external devices by which the programs and data are stored.

• Hard drives. The hard drive is a peripheral that has very high speed and high density. It is a very fast means of storing and retrieving data as well as having a large storage capacity in comparison with the other types of storage.
  

• Diskettes. The diskette drive allows the inout and output from a diskette, which is a round magnetic disk encased in a flexible or rigid case.
  

• CD-ROM. The CD-ROM is a rigid disk that hold a much higher density of information than a diskette and has much higher speed.
  

• USB Disk.  A USB disk is actually a form of a small, removable hard-drive that is inserted in the USB port of the computer. There are many names for it including pen drive, thistle drive, pocket disks and so on.
  

Computer Power

The term bytes and bits refer to how the machine store information at the lowest or closest to machine register and memory. Computers do not process information as words or numbers. They handle information in bytes. A byte is made up of 8 bits.

Bits and Bytes

A “bit’ (binary digit) is a unit of data in the binary numbering system. Binary means two, so a bit can assume two or more positions. Effectively, a bit is an on/off switch—on equals the value of 1 and off equals 0. Bits are grouped into collections of eight, which then function as a unit. The unit describes a single character in the computer and called as a “byte”.

Computer Speed

The CPU speed is measured in cycles per second which are called the clock speed of the computer. One million cycles per second is called megahertz (MHz). Today PC speeds are timed in billions per second or called gigahertz (GHz).

In general the higher the clock speed possessed by the CPU, the faster and the more powerful the computer. However, clock rate can be misleading , since different kinds of processors may perform a different amount of work in one cycle.       

         

Descriptive Terms Used In Computing

• Automatic- because it is self – instructed: that is, it automatically process data using computer programs called software.
• Electronic-  it uses microelectric components etched  on silicon chips for its circuitry. This means that its basic building blocks are microminiaturized.
• General purpose-  the user can program them to process all types of problems and can solve any problems than can be broken down into a set of logical, sequential instructions.

History Of Computers

The first true digital computer was called the Colossus Mark I, was built in 1943 with funding from the US military and used in airplane design and other complex engineering application. At the same time, Bell Laboratories was working on development of a computer, as were two scientists at the University of Pennsylvania, J. Presper Eckert and John Mauchly, later founders of the Eckert-Mauchly Corporation.

The prototype World War II computers were very different from today’s computer. First, they were big. A computer with much less power than ordinary desktop computer of the 1990’s took up an entire room. Second,  they were relatively few operations they could perform as compared to today’s computers. Third, they were difficult to program. In fact, they were programmed by scientists getting to the back of the computer and changing wires.

After the war, Eckert and Mauchly produced the first vacuum tube computer, the electronic numerical integrator and computer, more commonly known as ENIAC (Weik,1961).

First generation computers. The speed of the main processor was measured in access speeds. Access speed were measured in thousandths per milliseconds. First generation computers were physically huge but their power was much less than that of the average desktop computer of the 1900s. Main memory was less than 10 K of storage.

Second generation Computers were introduced in the late 1950s. they include the IBM 1401 and 1620. They used transistors instead of vacuum tubes. This meant less heat, improved reliability and much greater speeds. Second generation CPU access speed were measured in millions per second (microseconds). They were still quite large but transistors were smaller and more durable than vacuum tubes.

Third generation Computers were introduced in the mid- 1960s.These used micro miniature, solid state components. Third generation CPU access speeds were measured in billionths of a second (nanoseconds). They had about 110 K of main memory, and it was this generation in which hard disk drives were introduced. These hard disk drives were not encased in plastic cases, so they were so vulnerable to dust. That is why pictures taken during this era often show people in surgical type garb. They are trying to keep failure rate down by keeping the computer room as clean as possible.

The Rise of the Modern Personal Computers

In November 1972, Intel Corporation introduces the first commercial microprocessor, called the Intel 8008. This invention made the PC, or mircrocomputer. Shortly, two teenage boys named Steve Jobs and Steve Wozniak bought a microprocessor for $25 and built a very simple computer called “Apple”. They failed to interest Wozniak’s employee Hewlett Packard (Hp) Corporation, in their idea to build a small computer that people could have and use in their homes.


Not to be refused, the two Steve’s decided to pursue their dream. They began building the machines in Steve Job’s garage, and in May of 1976 they introduced their first computer at a meeting of the Homebrew Computer Club at which Paul Terryl, president of the Byte Shop Chain, ordered 50 computers. At that time Steve Job’s was 21 years old and Wozniak was 26. The Apple Computer Company and the first PC were born.

At the same time Jobs and Wozniak were working in the garage, IBM introduced the fourth generation mainframe, the IBM 370. This was the first mainframe family that had printed circuits. This computer was so fast that the old measurement of speed was unsuitable. Since CPU processes instruction, the CPU’s was measured by the speed with which it could processes instruction rather than accesses. Fourth generation computer CPU speeds were measured by instruction per second that they can process. The IBM 370’s CPU speed was measured in millions of instruction per second (MIPS). Today’s mainframe in billions of instruction per second (BIPS) or giga- instruction per second (GIPS).

Classes of Computers

Analog Computers

The analog computer operates on continuous physical or electrical magnitudes, measuring ongoing continuous analog quantities such as voltage, current, temperature and pressure. Selected physiologic mentoring equipment, which accepts continuous input/output signals,is in the analog computers.

Digital Computers

The digital computer operates on discrete discontinuous numerical digits using the binary numbering system. It represents data using discrete values for all data. Its data are represented by numbers, letters, and symbols rather than waveforms such as on a heart monitor.

Hybrid Computers

The hybrid computer, as its name implies, contains features of both the analog and digital computer. It is used for specific applications, such as complex signal processing and other engineering-oriented applications. It is also found in some monitoring equipment that converts analog signal to digital ones for data processing

Types of Computers

Supercomputers

The largest type of computer. Is a computational-oriented computer specially designed for scientific applications requiring gigantic amount of calculations. The supercomputer is designed primarily for analysis of scientific and engineering problems and for task requiring millions or billions of computational operations and calculations. This is found primarily in areas such as defense and weaponry, weather forecasting and scientific research.


Mainframes

The mainframe computer is the fastest and most expensive type of computer used in corporate America for processing, storing, and retrieving data. It is a large multi-user central computer that meets the computing needs- specially the large amount of repetitive calculations of bills, payroll and the like- of a large organization. A mainframe is capable of processing BIPS and accessing billions (GB) of character of data. 

Microcomputers ( Personal Computers or PCs)

Microcomputers are being used for an increasing number of independent applications as well as serving a desktop link to the programs of the mainframe. Hospital nursing departments are using PCs to process specific applications such as patient classification, nurse staffing and scheduling, and personal management applications. Found in educational and research setting where they are used to conduct a multitude of special educational and scientific functions. Microcomputers are also available as portable, laptop, notebook and handheld computers.

Handheld Computers

Handheld Computers are small, special function computers, although a few “full function” handheld computers were introduce in the late 1990s. Even though of smaller size than the standard desktop microcomputer some have claimed to have almost the same functionality and processing capabilities as the standard desktop microcomputer.

Common Hardware Peripherals

• Keyboard

The keyboard is the most common input device. It is similar to the keyboard of a typewriter and is connected to the box with a cord. There are several different types of keyboards: however, regardless of type they all have similar sections of keys; 1) typewriter keys, 2) function keys, 3) numeric keypad, 4) cursor keys, 5) toggle keys and 6) special operations keys.

     1) Typewriter key section is the largest and contains keys that follow the standard QWERTY arrangement of keys of standard typewriter.

    2) Function keys (F1-F12) are software-specific; they are programmable, since their function is dependent on the software program being processed. Three other keys on the keyboard labeled Shift, Ctrl and Alt expand the function keys by being used in combination with them to carry out other commands.

        3) Numeric Keypad is a second set of numeric keys that are placed differently on the keyboard than the alphabetic keys. The numeric keypad is a separate rectangle-shape calculator-type section that enables the user to enter numeric data more efficiently. This section of keys can be converted to represent other keys including moving the cursor in four direction just by turning on Num Lock key.

           4) Cursor keys are used to direct the pointer on the display monitor.

          5) Toggle keys are those that have dual purpose. When a toggle key is pressed once, the function is on and when pressed second time the function is off. The major toggle keys include Num Lock, Caps Lock and Scroll Lock and Insert/Type Over.

          6) Special Operation keys are unique to the microcomputer and used to make the keyboard easy to manipulate. The Home and End keys bring the cursor the beginning or end of the line, Print Screen prints the screen displays or saves it to the clipboard as a snapshot, Esc (escape) interrupts or cancels a function, a Tab key moves the cursor to predetermine set tabs, the Del key deletes texts, the Spacebar inserts black spaces in a line. The Enter key performs a variety of functions depending on the context of the program.

• Monitor

The monitor is displays screen component of a terminal that allows the user to see images, programs, commands the user sends to the computer, and results of the computers work (Output).

• Mouse and Trackball

The Mouse was introduced with the microcomputer as a new type of input device to replace moving the arrow keys on the keyboard. It is a hand-controlled mechanical device that electronically instructs the cursor move across the video display screen. As the user slides the mouse across the desktop pad, a ball on the bottom of the mouse senses the motion and transmits it to the cursor (Pointer) on the screen. The mouse atleast two buttons and sometimes a roller at the top. 

The left button is primarily to 1) select the icon, 2) activate the process and 3) implement the function to be performed. The Right button is a special function button, and its function is dependent on the program.

The trackball was developed for people who prefer a stationary device. Similar to a mouse, the trackball has the ball on the top and movement of the cursor is controlled by fingers rolling the ball in place.

• Floppy Disks/Diskettes and CD-ROMs

The Floppy Disk, commonly called Diskette, and the CD- ROMs are another form of secondary storage or auxiliary memory. They serve as both input and output. Data are read and written using disk drives in the same manner as with magnetic tapes and magnetic disks or CD readers and burners. A floppy disk is a flexible mylar plastic oxide-coated disk thinly covered with magnetic spots. It is available in 3 ½ and 5 ¼ in. sizes, though 5 ¼ in. floppy disk are rarely seen this days. Each floppy disk is sectioned into concentric rings or tracks ranging from 9-15 and each track is divided into sectors ranging from 40-48 or 80 – 96.

The CD-ROM can store around 640 MB of data (Foldoc, 2004) and is therefore a much more useful medium for the larger data, text and graphics files that many users wish to store and move from computer to computer today.

• Touch Pad and Mouse Button

The Touch Pad was developed by the makers of laptop computers for use in place of the mouse. A mouse is not practical for use in an airplane or other travel location. The touch pad is flat, rectangular depression on the keyboard that senses pressure and movement of the user’s finger.

• Light Pen/ Touch Screen

A light pen is a photosensitive device that responds to light image when placed against monitor screen. When the pen comes contact with the display screen it highlights the item and sends data to the computer.

Touch screens involves the use of special filter on a monitor screen that allows the screen to “sense” the pressure of the user’s fingers on a particular position on the screen. That pressure can signal the computer to initiate an action (similar to a mouse click) or can a function to let the user select a particular item on the screen, such as on a menu. Sensors on the screen pinpoint the X and Y axis location touched by a user.

• Optical Character Recognition

Optical Character Recognition (OCR) is a specialized computer input medium that allows data to be read directly from a form or document. An electronic optical scanning device, a wand reader, or a bar code reader reads special marks, bar codes, number, letters or characters. The scanner used in a grocery store uses a special type of OCR. Such device converts the optical marks, characters and bar codes into electrical signals that become computer input.

• Magnetic- Ink Character Recognition

Magnetic –Ink character recognition (MICR) is another medium for reading characters by computers. Here the characters are made of magnetized particles printed on paper. A MICR reader can examine the shape of the magnetic – ink characters and convert them into binary code for computer input. The most common example of a MICR is the magnetized characters imprinted on checks, which most bank uses.

• Voice Synthesizer

A voice synthesizer allows users to input data into the computer by speaking into a connected microphone. Also known as a speech synthesizer, it digitizes the sound for processing by the CPU. Although automatic recognition of the human voice is not yet perfected, voice input is used in situations requiring only a few spoken words and it is becoming a common medium for all computer system.

• Imaging

The field of computer imaging exploded in the 1980’s and 1990’s with the enormous development of medical imaging. Many of the advanced imaging technologies, such as computerized axial tomography (CAT scan) and magnetic resonance imaging (MRI) are computer – enhanced imaging technologies.

Several different types of image input device are available that primarily transform images from various types of graphics into digital form, which the computer can accept, represent on the screen and process.

• Digital Versatile Disk

A DVD looks and feels like a CD-ROM but hold much more information and contains many more multimedia features. DVD technology is in the process of replacing most CD-ROM technology.

• Printers

The printer, the most important output device, converts information produced by the computer system into printed form, rendering data in the binary code into readable English. The major types of printed output include printed hard copy (paper), microfilm, photographs, and graphic copy. The printer’s output, known as hard copy, is output produced on paper.

• Modems

The modem is a communication device used to connect a terminal with a mainframe or another computer. A modem (modulating and demodulating device) translates digital data into waves(analog) for transmission over the communication lines to the computer system and converts the waves back to their original digital form for input into the computer. Modems connect the user with a remote computer’s CPU, enabling communication through telephone lines. By dialing the remote computer’s modem, data can be both send and received from outside sources.

Basic Computer Network Hardware

A network is a cooperative interconnected computers for the purpose of information interchange. The networks of greatest interest include Local Area Network (LAN), Wide Area Network (WANs) and the Internet, which is a network of networks. A LAN usually supports the interconnected computer needs of a single company or agency. The computers are physically located close to each other and generally, only members of the company or agency have legitimate access to the information on the network. WANs support geographically dispersed facilities, such the individual grocery stores in a national chain. A subset of WANs include the metropolitan area network (MANs) that support and connect the many buildings of local government agencies or university campuses.

Network hardware

The role hardware in a network is to provide an interconnection between computers. For a computer to participate on a network, it must have atleast two pieces of hardware.

1) Network adapter or network interface card

A network interface card(NIC) is a computer circuit board or card that is installed in a computer so that in can be connected to the network. PCs and workstations on LANs typically contain a NIC specifically designed for the LAN transmission technology, such as Ethernet. NICs provide a dedicated, full-time connection to a network.

2) Communication medium ( cabling)

The “communication medium” is the means by which actual transfer of data from site to another takes place. Commonly used communication media include twisted pair cable, coaxial cable, fiber-optics, telephone lines, satellites and compressed video. Most of the time, the choice of a communication medium is based on the following:

•  Distance
• Relatively short distances are required for compressed video and coaxial cables. For much longer distances, fiber-optics, telephone lines and satellite transmission are used

•  Amount of data transfer
• Large amount of data (especially video) are best handled with coaxial cables and compressed video and through satellite communications(satellite and compressed video are very expensive). Smaller amounts of data or serial (nonvideo) streams are best handled through the other wire types, such as twisted pair copper wire and optical fiber and are less expensive.

•  How often the transfer is needed
• Coaxial works best for locally wired networks that are used constantly by a very limited number of users. Telephone wires work well for the relatively high usage public network (like the internet) but are more likely to get overload when many users try to use the system at the same time.

• Availability
• Availability depends on cost, transmission, number of users(who might clog up the system), weather conditions (satellites) and so on.

Telephone Line Communications

Specialized phone line called integrated services digital network (ISDSN) lines are used to carry out communications across phone lines. ISDSN is a set of communication standards for optical-fibers that carry voice, digital and video signals across phone lines.

Cable Modem

For many people telephone modems have proven much too slow a medium for their internet connection and many have moved to cable modem for their home internet connectivity. Cable modem uses the same type of connection that of cable TV uses. A cable modem can server up to 1,000 users at the same time, although at that point the performance may begin to degrade. A cable network can achieve speeds up to 30-40 Mg per second.

Servers

The concept of a server is very important when networks are discussed today. For a network to exist, there must be a server. Most networks today use client/server approach. In a pure client/server approach, one computer is the core or server computer that receives requests from the client (user) computer and fulfills those requests.

1) A server is a computer program that provides services to other computer programs in the same computer or in the other computers on a network

2) The computer that runs the server program is also frequently referred to as “the server”

3) In the client/server programming model, a server is a program that awaits and fulfills request from the client programs in the same or other computers. A given application in a computer may function as a client with request for services from other programs and a server or request from other programs.

Architecture

In informatics, architecture refers to overall physical structure, peripherals, interconnection within the computer and its syste software, especially the operating system. Computer architecture can be divided into five fundamental components: input/output, storage, communication, control and processing.

When networks are discussed, architecture refers to how communication among the various computers in the network is accomplished. Broadly speaking there are two types of network architectures.

•  Broadcast
• Here the communication is done by transmitting the same information to all the computers in the network that are expected to respond to it. This typically used in LANs.
•  Point- to- point
• The computer for which information is intended is identified first and the communication is only to that particular computer. This is typically used in dial – up networking.

Topology

Topology defines how the network computer in a LAN are interconnected within a physical area and describes their physical interconnection. Several possible topologies are the following:

•  Bus
• A Bus is a network topology or circuit arrangement in which all the node computers are directly attached to a line. Therefore, all communications travel through each of the node of the computers. In this fashion all computers are connected in a parallel line to each other. The big advantage of this topology is that if one computer fails, other computers still can access the information. This structure is decentralized.

• Star
• This is a centralized structure where all computers are connected through a central computer, called a server. If this central computer fails, information cannot be sent or received by any of the computers connected to this server.

• Ring
• Token rings work by having the server pass a marker, or “token” to the computer that is next in line to communicate. No computer can send or receive data unless it is the target of the token. In this way, collisions between two workstations that wish to transmit information at the same time are avoided. It should be noted that, generally, the token is passed so rapidly that the LAN users may never know they had to wait. A token ring structure can support networks in which the computers are up to 124 miles apart.

•  Hub
• A form of ring topology. A hub consist of a “backbone” or main circuit, attached to a number of ports to which devices can be attached. In the Hub, all computers are connected to a central hub processor that contains networking software and provides communication among various computers on the network.

• Arcnet
• Another type of ring technology used for LANs is arcnet. It uses what is called a “token-bus” system for managing line sharing among all the users on the network. It works well for LANs in which all the links are physically near each other. While not as powerful as some other topologies, it is by far the least expensive.