What is a Process?
A process is a computer program running on a computer.A computer program in simple terms is an executable set of commands for the computer to perform. A process is an actively running program which may or may not be running in the background. A program running in the background is one that the computer user may not be aware of, but it may be providing useful services such as an ability to connect to other computers.
THE CENTRAL PROCESSING UNIT
This is the brain of the computer; it reads and executes program instructions, performs calculations, and makes decisions .The CPU is responsible for storing and retrieving information on disks and other media. It also handles information on from one part of the computer to another like a central switching station that directs the flow of traffic throughout the computer system.
DIFFERENT FACES OF A CPU
MAIN COMPONENTS OF CPU
WHAT DOES THE CPU DO?
Carries out instructions and tells the rest of computer system what to do. Sends command signals to the other components of the system. Perform arithmetic calculations and data manipulation. Holds data and instructions, which are in current use.
CONTROL UNIT (CU) Directs the entire computer system to carry out stored program instructions.
Instructs the arithmetic logic unit which arithmetic operations or logical operation is to be performed.
ARITHMETIC LOGIC UNIT (ALU) Executes arithmetic and logical operations. Arithmetic operations include addition, subtraction, multiplication and division. Logical operations compare numbers, letters and special characters.
Holds data and instructions for processing. RAM (Random Access Memory) - used to store instructions and data needed while processing. b) ROM (Read Only Memory) - ROM comes with instructions permanently stored inside and these instructionscannot be over-written by the computers CPU.
MICROPROCESSORA silicon chip that contains a CPU. In the world of personal computers, the terms microprocessor and CPU are used interchangeably.It's sometimes called a logic chip. It is the "engine" that goes into motion when you turn your computer on.At the heart of all personal computers and most workstations sits a microprocessor. Microprocessors also control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles.
Three basic characteristics differentiate microprocessors: Instruction set: The set of instructions that the microprocessor can execute. bandwidth : The number of bits processed in a single instruction. clock speed : Given in megahertz (MHz), the clock speed determines how many instructions per second the processor can execute.
MICROPROCESSOR (cont.)In both cases, the higher the value, the more powerful the CPU. For example, a 32-bit microprocessor that runs at 50MHz is more powerful than a 16-bit microprocessor that runs at 25MHz.
In addition to bandwidth and clock speed, microprocessors are classified as being either RISC (reduced instruction set computer) or CISC (complex instruction set computer).
WHAT IS INPUT? Input is any data or instructions you enter into the memory of a computer. Once input is in memory, the CPU can access it and process the input into output. Four types of input are data, programs, commands, and user responses.
4 TYPES OF INPUTData is a collection of unorganized facts that can include words, numbers, pictures, sounds, and videos. A program is a series of instructions that tells a computer how to perform the tasks necessary to process data into information. Programs are kept on storage media such as a floppy disk, hard disk, CD-ROM, or DVD-ROM.
4 TYPES OF INPUT (cont.) A command is an instruction given to a computer program. Typing keywords or pressing special keys on the keyboard can issue commands.A user response is an instruction you issue to the computer by replying to a question posed by a computer program, such as do you want to save the change you made?
INPUT DEVICESAn input device is any hardware component that allows you to enter data, programs, commands, and user responses into a computer. Input devices include the keyboard, pointing devices, scanners and reading devices, digital cameras, audio and video input devices for physically challenged user.
Many input devices use an electronic pen instead of keyboard or mouse for input. Some of there devices require you to point to onscreen objects with the pen ;others allow you to input data using drawings, handwriting, and other symbols that are written with the pen on a surface.
LIGHT PEN A light pen is a handheld input device that contains a light source or can detect light. Some light pens require a specially designed monitor, while others work with a standard monitor.
LIGHT PENInstead of touching the screen with your finger to interact with the computer, you press the light pen against the surface of the screen or point the light pen at the screen and then press a button on the pen.
PEN COMPUTING Many handheld computers also allow inputting data using an electronic pen (also called a stylus) looks like a ballpoint pen but uses an electronic head instead of ink. Pen computers use handwriting recognition software that translates the letters and symbols used in handwriting into character data that the computers can use.
GRAPHICS TABLET A graphics tablet, also called a digitizer or digitizing tables, consists of a flat, rectangular, electronic plastic bond used to input drawings, sketches, or other graphical data.
Each location on the graphical tablet corresponds to a specific location on the screen. When you draw on the tablet with either an electronic pen or a puck, the tablet detects and converts the movements into digital signals that are sent into the computer.
TRACKBALLA mechanical mouse has ball mechanism on the bottom, a trackball is a station- aryl pointing device with a ball mechanism on its top . Although it shares characteristic with a mouse, a trackball is not as accurate as a mouse .A trackballs ball mechanism also requires frequent cleaning because it picks up oils from your fingers and dust from the environment.
CAMERADigital camera allows you to take pictures and store the photographed images digitally instead of on traditional film.
With some digital cameras, you download, or transfer a copy of, the stored pictures to your computer by connecting a cable between the digital camera and your computer and using special software included with the camera.
The three basic types of digital cameras are studio cameras, field cameras, and point-and shoot- cameras.
MOUSE The mouse is the most widely used pointing device because it takes full advantage of a graphical user interface.
A mouse is an input device that is used to control the movement of the pointer on the screen and to make selections from the screen.
MOUSE TYPES A mouse that has a rubber or metal ball on its underside is called a mechanical mouse. When the ball rolls in a certain direction, electronic circuits in the mouse translate the movement of the mouse into signals that are sent to the computer. Another type of mouse, called an optical mouse, has no moving mechanical parts inside; instead it uses devices that emit light to detect the mouses movement.
SCANNERS Scanners have become an important part of the home office over the last few years. Scanner technology is everywhere and used in many ways:
Flatbed scanners, also called desktop scanners, are the most versatile and commonly used scanners. In fact, this article will focus on the technology as it relates to flatbed scanners.
SCANNERS (cont.)Sheet-fed scanners are similar to flatbed scanners except the document is moved and the scan head is immobile. A sheet-fed scanner looks a lot like a small portable printer.
SCANNERS (cont.)Handheld scanners use the same basic technology as a flatbed scanner, but rely on the user to move them instead of a motorized belt. This type of scanner typically does not provide good image quality. However, it can be useful for quickly capturing text.
SCANNERS (cont.)Drum scanners are used by the publishing industry to capture incredibly detailed images. They use a technology called a photo multiplier tube (PMT). In PMT, the document to be scanned is mounted on a glass cylinder. At the center of the cylinder is a sensor that splits light bounced from the document into three beams. Each beam is sent through a color filter into a photo multiplier tube where the light is changed into an electrical signal.
KEYBOARD TYPESA standard computer keyboard sometimes is called a QWERTY keyboard because of the layout of its typing area.
Pronounced KWER-tee, this keyboard layout is named after the first six leftmost letters on the top alphabetic line of the keyboard. Because of the way the keys are organized, a QWERTY keyboard might limit your typing speed.
KEYBOARD TYPES (cont.)A keyboard with an alternative layout was designed to improve typing speed called the Dvorak keyboard (pronounced de-vor-zhak),
This type of keyboard places the most frequently typed letters in the middle of the typing area.
Despite the more logical design of the Dvorak keyboard, the QWERTY keyboard is more widely used.
MICROPHONEA microphone is used to record sound. The sound is then saved as a sound file on the computer.
JOYSTICKUsers running game software such as a driving of flight