ELEMENTS OF COMPUTER SYSTEM
Computer System is a complete, working computer. The computer system includes not only the computer, but also any software and peripheral devices that are necessary to make the computer function.
1. 2. 3.
Hardware Software Peopleware / Liveware
HARDWARE It is best described as a device that is physically connected to your computer or something that can be physically touched.
INPUT
DEVICE – any device that allows the person to communicate information to the computer / gives information to the computer system so that it can perform its tasks
Bar Code Reader – is an input device used to scan a Bar Code Reader pattern of lines using optical sensing techniques the line patter is coded information about the item to which it relates (e.g. the price and description of an item of merchandise). Digital Camera – record images in digital form. Digitizing Tablet – an input device that enables you to enter drawings and sketches into a computer. A digitizing tablet consists of an electronic tablet and a cursor or pen. A cursor (also called a puck) is similar to a mouse, except that it has a window with cross hairs for pinpoint placement, and it can have as many as 16 buttons. Keyboard – is the most commonly used input device, similar to a typewriter keyboard that is a part of a terminal that is connected to a computer elsewhere. Mouse – which has a ball on its underside, is rolled on a flat surface, usually the desk on which the computer sits / a device that controls the movement of the cursor or pointer on a display screen, originally designed by Xerox Trackball – it is a variation on the mouse, but it is an upside mouse-you roll the ball directly with your hand. Touchpad – your finger as the pointer/ is a pressuresensitive pad that is smaller, more accurate, thinner, and less expensive to build than a trackball. Scanner – a device that can read text or illustrations printed on paper and translate the information into a form the computer can use. A scanner works by digitizing an image – dividing it into a grid of boxes and representing each box with either a zero or a one, depending on whether the box is filled in.
Handheld Electronic Organizers – are small mobile computers that accept input through a penlike instrument called a stylus that is used to write n the computer’s screen. Microphone – device for converting sound wave into electrical energy. Web Camera – is a camera that is in some way connected to the World Wide Web, or Internet. Trackpad – a small, touch-sensitive pad, usually a couple of inches square, which acts as an alternative to a mouse on some notebook/palmtop computers. It works by sensing fingertip pressure. Joystick – a manual control consisting of a vertical handle that can move freely in two directions; used as an input device to computers or to devices controlled by computers. Touch Screen – a type of display screen that has a touch-sensitive transparent panel covering the screen. Instead of using a pointing device such as a mouse or light pen, finger is used to point directly to objects on the screen. Light Pen – an input device that utilizes a lightsensitive detector to select objects on a display screen. A light pen is similar to a mouse, except that with a light pen the pointer can be moved to selects objects on the display screen by directly pointing to the objects with the pen. Stylus – a pointing and drawing device shaped like a pen. Stylus is used with a digitizing tablet or touch screen. Sensor – is a device, which responds to an input quantity by generating a functionally related output usually in the form of an electrical or optical signal. Optical Character Recognition – permits users to input printed or typewritten documents with a scanner. Pen-Based Computing – involves the use of a special pen on a monitor surface, as with a personal digital assistant. Voice Recognition System – activated by user’s voice after voice has been programmed into the computer; currently accepts limited number of vocal commands.
OUTPUT DEVICE - It is anything that allows the computer to communicate information to the user.
Monitor – It is used to display soft copy output. Varieties of Screens 1.
2.
Categories of Scanners 1.
Flatbed Scanner – It is a typically scans one sheet at a time, although some offers an attachment for scanning multiple sheets. Advantage: It can be used to scan bound documents, such as pages from books and other bulky items.
2.
Sheetfeed Scanner – Motorized rollers feed the sheet across the scanning head. Advantage: It is usually designed to fit neatly between the keyboard and the monitor.
3.
Handheld Scanner – The least expensive and least reliable of the three, is a handy portable option Disadvantage: It is often difficult to get a good scan because the user must move the scanner in a straight line and fixed rate. Optical Mark Reader – was designed initially to read penciled or graphic information on exam answer sheets.
3.
Cathode Ray Tube (CRT) – It uses a technology called raster scanning, a process of sweeping electron beams across the back of the screen. Liquid Crystal Display (LCD) – A flat display often seen on watches and calculators, sometimes used in laptop computers. Plasma – consists of ionized neon / gas (plasma) sealed between two glass plates. One glass plate encases a set of horizontal wires and the other a set of vertical wires. The images produced by plasma display are generally very clear, detailed, and not subject to the flicker associated with monochrome monitors. Plasma displays are generally more expensive than their CRT counterparts.
Printer – It is a device that produces information on paper output. Types of Printer 1. Non-Impact Printer – places an image on a page without physically touching the page. 1.1 Laser Printer – use a light beam to help transfer images to paper 1.2 Ink-Jet Printer – Which spray ink from a multiple jet nozzles, can print in both black and white and several different of colors of ink to produce excellent graphics.
2. Impact Printer – uses some sort of physical contact with the paper to produce an image, physically striking paper, ribbon, and print hammer together. 2.1 Daisy Wheel Printer 2.2 Dot Matrix Printer 2.3 Cain Printer 2.4 Band Printer
Voice Output – It is typically used when an inquiry is followed by a short reply, such as a balance or flight time. Many businesses have found another creative uses for voice output over the telephone. Speaker – an output device producing sounds. Speech Synthesizer – increase a message as temporary output that computer users hear. Microfilm or Microfiche – are reduced sized photographic reproductions of printed information on film cards. The cards can be read using microfiche readers and printed using microfiche printers. Plotter – a device that draws pictures on paper based on commands from a computer. Plotters differ from printers in that they draw lines using a pen. As a result, they can produce continuous lines, whereas printers can only simulate lines by printing a closely spaced series of dots. Multicolor plotters use differentcolored pens to draw different colors.
types of ports. Internally, there are several ports for connecting disk drives, display screens, and keyboards. Externally, personal computers have ports for connecting modems, printers, mice, and other peripheral devices. Examples: Universal Serial Bus (USB), Parallel (PS2), Serial.
Expansion Slots – a connector in a computer into which an expansion card can be plugged. The connector supplies power to the card and connects it to the data bus, address bus and control signals of the motherboard. Examples: ISA (International Serial Architecture), PCI (Peripheral Component Interface), AGP (Accelerated Graphics Port).
Bus – a collection of wires through which data is transmitted from one part of a computer to another. Registers – are temporary storage areas for instruction or data - They are not part of the memory rather they are special additional storage locations that offer the advantage of speed. Microprocessor – a miniaturized central processing unit can be etched on a chip, a tiny square of silicon. - It is usually expressed in megahertz (MHz).
INPUT/OUTPUT DEVICES – a piece of hardware that is used
Bus lines – is a set of parallel electrical paths, usually copper tracing on the surface of the motherboard, which internally transports data from one place to another within the computer system.
for both providing information to the computer and receiving information
Disk Drive – a computer hardware that holds and spins a magnetic or optical disk and reads and writes information on it. Hard Disk Drive – a rigid magnetic disk mounted permanently in a drive unit. Optical Disc – a direct-access disk, which has information recorded on it with a laser beam that burns pits into its surface. Modem – the modem modulates the computer output to an acceptable signal for transmission and then demodulates the signal back for computer input.
Cache – is a relatively small block of very fast memory designed for the specific purpose of speeding up the internal transfer of data and software instructions. MACHINE CYCLE Control Unit
ALU
DECODE
EXECUTE
SYSTEM UNIT – the main part of a personal computer. The
system unit includes the chassis, microprocessor, main memory, bus, and ports, but does not include the keyboard or monitor, or any peripheral devices.
Main Memory FETCH
Central Processing Unit (CPU) – it is the brains of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place o Control Unit – supervises or monitors the functions performed by the entire computer system according to conditions set forth by the stored program. o Arithmetic/Logic Unit – the part of a computer that performs all arithmetic computations, such as addition and multiplication, and all comparison operations. The ALU is one component of the CPU. o Memory Unit – is somewhat like an electronic filing cabinet capable of holding data or instructions. Motherboard – the main circuit board of a microcomputer. The motherboard contains the connectors for attaching additional boards. Typically, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers required to control standard peripheral devices, such as the display screen, keyboard, and disk drive. Collectively, all these chips that reside on the motherboard are known as the motherboard’s chipset. Ports – an interface on a computer to which you connect a device. Personal computers have various
STORE
The first two steps together are called the actual instruction time, or I-Time or Instruction cycle or I-cycle. 1. 2.
The control unit fetches the instruction form the memory. The control unit decodes the instruction and directs that the necessary data be moved from memory the arithmetic/logic unit.
Steps 3 and 4 together are called execution time, or E-Time or Execution cycle or E-cycle. 3. 4.
The arithmetic/logic unit executes the arithmetic/logical instruction, given as the actual operation on the data. The arithmetic/logic unit stores the result of this operation in memory or in a register.
STORAGE DEVICES 1.
Primary Storage – also called as main memory; a non-volatile, temporary type of storage. Examples: RAM – Random Access Memory ROM – Read Only Memory PROM – Programmable ROM
EEPROM – Electronic Erasable Programmable ROM 2.
DATABASE MANAGEMENT - It is the management of a collection of interrelated facts-handles data in several ways. Examples: DBaseIII, MS Access, Foxbase, FoxPro
Secondary Storage – also called as auxiliary memory, a volatile, permanent type of storage Examples: Hard disk Floppy Disk Optical Disk (Compact Disks)
GRAPHICS - Visual information is usually more compelling than a page of numbers. Examples: Adobe Photoshop, Corel Draw COMMUNICATIONS - It can hook a phone up to the computer and communicate with the computer at the office or access data stored in another computer in another location. Examples: Win Popup
SOFTWARE
It I the planned, step-by-step set of instructions required to turn data into information-that makes a computer useful.
DESKTOP PUBLISHING – to create personalized cards, business cards, letterheads, etc. Examples: Hallmark, Disney’s, etc.
SYSTEM SOFTWARE – consists of programs designed to facilitate the use of the computer by the user. Any software required supporting the production or execution of application programs but which is not specific to any particular application. 1.
2.
3.
4.
Operating System - an important part of the system software which tells the computer how to perform functions such as how to load, store and execute an application program an how to transfer data between the input/output devices and main memory. Examples: MS-DOS, MAC-OS, all versions of Windows, UNIX Programming Languages – software which are used to create software. Examples: ADA, LISP, C, Pascal, Basic, etc. Compilers / Translators – is a system program that converts the English-like instructions used by computers programmers into the machine-readable code used by the hardware. Examples: Assembly, COBOL Utility Program – perform such standard tasks as organizing and maintaining data files, translating programs written in various languages to a language acceptable to the computer. Examples: Text Editor, Defragmenter, File Compressor such as WinZip, etc.
APPLICATION SOFTWARE - is applied to a real-world task, it can be used to solve a particular problem or to perform a specific task. 1.
Customized – typically created to perform a particular task. Examples: payroll, monitoring, registration, point of sales, video rentals, etc.
2.
Packaged – purchased programs which are required for common business and personal applications Examples are the following: WORD PROCESSING - it is the most widely used personal computer software that used for memos, reports, correspondence, minutes of meetings, and anything else that someone can think of to type. Examples: MS-Word, WordStar, WordPerfect, AmiPro ELECTRONIC SPREADSHEETS - It is made up of columns and rows of numbers have been used at business tools for centuries. Examples: MS Excel, Lotus 1-2-3, QuattroPro
CAI/CAD/CAM – Computer Aided Instructions, Computer Aided Design, Computer Aided Manufacture
PEOPLEWARE
This component is made up of the people responsible for maintaining, operating, programming, and analyzing the output generated by the computer system.
Computer Operator – works in the computer room and is responsible for a number of different tasks. Data Library- is usually located close to the computer room and usually staffed by a data librarian. Data Entry Personnel – are responsible for entering large volumes of data into the computer system. System Analysts – review current or proposed applications within a company to determine if the applications should be implemented using a computer. Computer Programmers – design, write, test and implement specialized programs that process data to computer. Database Administrator – an important function within the information system department is the management of data.
Management Information System Department (MISD) - Management within an information systems department varies depending on the size and complexity of the department. Persons inside MISD 1. Systems Manager – overseas the activities in the system analysis and design area of the department. 2. Programming Manager – is in charge of all programmers within the department. 3. Operation Managers – overseas the operational aspects of the department such as scheduling, maintenance, and operation of the equipment. 4. Information System Department Manager – is in charge of the entire department and may have the title Vice President of Information System, or Chief Information Officer. EDP (Electronic Data Processing) EDP, an infrequently used term for what is today usually called "IS" (information services or systems) or "MIS" (management information services or systems), is the processing of data by a computer and its programs in an environment involving electronic communication. EDP evolved from "DP" (data processing), a term that was created when most computing input was physically put into the computer in punched card form and output as punched cards or paper reports.
