Basic Computer Concept in Computer Science

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Data Representation and Digital Electronics
Data Representation makes it possible to convert letters, sounds, and images into electrical signals Digital Electronics makes it possible for a computer to manipulate simple “on” and “off” signals to perform complex tasks

Digital Data Representation
Why are computers digital ?

Digital Device works with discrete -distinct or separate data or digits, such as 1 and 0 Analog Device works with continuous data

Computers are digital because computer designers have found it to be a relatively simple, dependable, and adaptable technology. A digital computer is a simpler technology than an analog computer. Most computers use the simplest type of digital technology, their circuits have only two possible states.

Digital Data Representation
How can a computer represent numbers using bits ?

Computers represent numeric data using the binary number system, also called “base 2”

Numeric Data the numbers that might be used in arithmetic operations Binary Number System has only two (2) digits : 0 and 1 allows computers to represent virtually any number simply by using 0s and 1s conveniently translates into electrical “on” and “off” signals

Digital Data Representation
How can a computer represent words and letters using bits ? Character Data consists of letters, symbols and numerals that will not be used in arithmetic calculations A digital computer uses a series of bits to represent letters, characters, and numerals. ASCII pronounced as “ ASK ee” stands for American Standard Code for Information Interchange requires only seven bits for each character Extended ASCII a superset of ASCII uses eight bits to represent each character provides codes for 128 additional characters

Digital Data Representation
How can a computer represent words and letters using bits ? EBCDIC pronounced as “EB seh dick” stands for Extended Binary Coded Decimal Interchange Code an alternative 8-bit code usually used by IBM mainframe computers UNICODE pronounced as “YOU ni code” provides codes for 65,000 characters and makes use of 16 bits

Digital Data Representation
How does a computer convert sounds and pictures into codes ? A computer must somehow digitize colors, notes, and instrument sounds into 1s and 0s, in order to work with sounds and pictures. Computers convert colors and sounds into numbers, which can be represented by bits. A red dot on your computer screen might be represented by 1100, a green dot by 0010.

Digital Data Representation
When a computer works with a series of 1s and 0s, how does it know which code to use? All of the things that computer works with is stored in files as a long series of 1s and 0s. The computer needs to know whether to interpret those 1s and 0s as ASCII code, binary numbers, or the code for a picture or sound. Most computer files contain a file header with information on the code that was used to represent the file data, to avoid confusion. A computer can now tell how a file’s contents were coded by reading the header information.

Digital Electronics
How can I tell the difference between bits and bytes? bit binary digit can be further abbreviated as a lowercase “b” byte composed of eight (8) bits usually abbreviated as an uppercase “B” nibble composed of four (4) bits a halfway between a little bit and a big byte Storage space is usually expressed in bytes while transmission speeds are expressed in bits.

Digital Electronics
How does a computer store and transport all of those bits ?

Bits take the form of electrical pulses that can travel over circuits. The circuits, chips, and mechanical components forming a computer are designed to work with bits. These components are housed within the computer’s system unit.

Digital Electronics
How do chips fit together to make a computer? Motherboard also known as main board the computer’s main circuit board houses all essential chips and provides connecting circuitry between them Some chips are permanently soldered in place, while other chips are plugged into special sockets and connectors. The chips might be gathered together on a separate small circuit board, which can then be plugged into a special slot-like connector.

Microprocessor Basics
Microprocessor sometimes known as processor an integrated circuit designed to process instructions the most significant component of computer and usually the most expensive single component executes instructions that are provided by a computer program Instruction Set list of instructions that a microprocessor can perform hardwired into the processor’s circuitry comprising of basic arithmetic and logical operations, fetching data, and clearing registers Memory is the electronic that holds place for instructions and data which the microprocessors can reach quickly

Today’s Microprocessors
Which companies produce most of today’s popular microprocessors ? Intel world’s largest chipmaker and supplies a sizeable percentage of the microprocessors that power personal computers introduced the world’s first microprocessor , the 4004, during 1971 AMD (Advanced Micro Devices) Intel’s chief rival in the PC chip market produces microprocessors that work just like Intel's chips, but a lower price

Today’s Microprocessors
Which of the microprocessors is the best ? Intel Original Pentium : 1993 Pentium II : 1997 Pentium III : 1999 Pentium IV: 2000 Itanium : 2001 Celeron processors : Intel’s budget model AMD Athlon processors : Direct competitors to Intel’s Pentium line Duron processor : AMD’s budget model The microprocessor that’s “best” for you depends on your budget and the type of work and play that you plan to do.

Components of Data Processing
Data processing is a technique of collecting, manipulating and distributing data to achieve certain functions Objective: to convert raw data into information that can be used in decision making Computer Systems • A system is a collection of objects, procedures, or techniques that interact in regulated manner to form an organized whole

Components of Data Processing
Central Processing Unit (CPU) integrates and coordinates overall operations composed of three (3) units:

The CPU sub-units: ALU, Control Unit and Primary Storage

Components of Data Processing
Central Processing Unit (CPU) Control Unit maintains order and controls activity in the CPU does not process or store data but it directs the sequence of operations interprets the instructions of a program in storage and produces signals that act as command circuits to execute the instructions Arithmetic/Logic Unit (ALU) performs arithmetic computations and logical operations Primary Storage Unit holds instructions, data, and intermediate and final results a reusable, fast storage medium, directly accessible by the control unit

Components of Data Processing
Input/Output Subsystem provides the mechanism for communications between the CPU and the outside world input subsystem - reads data and converts them into electronic pulses output subsystem - reports the results of the processing by the CPU Memory Subsystem also known as the “secondary storage”, allows for extra data storage, exceeding the CPU’s primary storage an efficient and compact means of sorting large amount of data, ready for retrieval or further processing retrieval time is slower than the primary storage

I/O Components
Common I/O Peripherals Keyboard

Mouse

Monitor

Hard disk

Printer

I/O Components
Other I/O Devices CD-ROM drive

Modem

Sound Card

Scanner

Storage Components
Memory Random Access Memory (RAM) is a type of computer memory chip that allows instructions and data to be stored, changed and retrieved by the user Read Only Memory (ROM) is a memory chip that allows only readout capability Programmable Read Only Memory (PROM) enables the user to add special information to the ROM supplied by the manufacturer as part of the system Virtual Memory is an imaginary memory area supported by the software in conjunction with the hardware

Storage Components
Mass Storage Device Floppy Disks

Compact Disk (CD)

Zip Disk

Classification of Computers
Minicomputers, Microcomputers and Mainframes Microcomputers are small desktop systems with limited I/O devices --- usually only a keyboard for input, a floppy disk for storage, and a monitor for output Minicomputer is a general-purpose computing device, either rack-mounted or small enough to fit in a desktop Mainframe is a very large and expensive computer capable of supporting hundreds, or even thousands of users simultaneously Desktop PCs medium sized computers relatively inexpensive and designed for individual users

Classification of PCs
Supercomputers fastest type of computers very expensive and are employed for specialized applications that require heavy mathematical calculations that smaller computers may not be able to do • weather forecasting • animated graphics • fluid dynamic calculations • nuclear energy research RISC vs. CISC Reduced Instruction Set Computer (RISC) Complex Instruction Set Computer (CISC)

Software, Programs and Support Modules
Software comprises of computer programs , support modules, and data modules that work together in order to provide a computer with the instructions and data necessary for carrying out a specific type of task Program a set of instructions that tells a computer how to solve a problem or carry out a task Support Module provides an auxiliary set of instructions that can be used in conjunction with the main software program not designed to be run by the computer user

Software, Programs and Support Modules
Why does a software requires so many files? Most software packages include at least one executable program file, several support modules, and one or more data modules. It is for the programmers’ great deal of flexibility and efficiency. Most of the support modules contain “generic” program instructions that can be used to work with various programs. These techniques affect the process of installing and uninstalling software.

How Software Works
How does a high-level language relate to the microprocessor’s instruction set? Machine language is the only language that can be understood by a computer’s microprocessor. Instructions written in a high level language must be translated into machine language before a computer can use them. A special type of programs called translators, convert instructions from a high-level language into machine language.

How Software Works
Assuming that a VideoFactory, a video editing program, was installed on your computer, which is running Windows. You click the Start button, then select VideoFactory from the Programs menu. The instructions for Vidfact.exe are loaded into RAM and then sent to the microprocessor. The VideoFactory window opens and the graphical controls for video editing tasks appear. The programs wait for you to select a control by clicking it with the mouse. The program follows its instructions and performs a pre-specified action. The program continues to respond to the controls that you select until you click the Close button, which halts execution of the program instructions and closes the program window.

Operating System
What does an operating system do A computer’s software acts similarly with the chain of command in an army. Using application software, you issue a command. Application software tells the operating system what to do. The operating system instructs the device drivers, device drivers instruct the hardware and the hardware actually does the work.

Operating System
What does an operating system do

The operating system interacts with application software, device drivers, and hardware to manage a computer’s resources. While interacting with application software, operating system is busy behind the scenes with other tasks.

Operating System
How does an operating system affect the “look and feel” of application software? An operating system typically provides user interface tools, such as menus and toolbar buttons, that define the “look and feel” for all of its compatible software. Apple computer released its popular Macintosh computer in 1984, which featured a GUI operating system and applications. During 1992, when Windows 3.1 became standard issue on most PCs, GUIs did catch on in the PC market, replacing a command-line interface that had given many people a string aversion to computers in general.

Operating System
Where is the operating system The entire operating system is small enough to be stored in ROM for typically handheld computers and video game consoles. For nearly all personal computers, servers, workstations, mainframes, and supercomputers, the operating system program is quite large, so most of it is stored on a hard disk. The bootstrap program provides the instructions needed to load the core parts (kernel) into memory when the system boots. Customization utilities and other parts of the operating system are loaded into memory as they are needed.

Operating System
Do I ever interact directly with the OS

• Launch programs • Customize the user interface • Manage Files • Configure Equipment • Get Help

Operating System
Are different operating systems needed for different computing tasks ? Single-user operating system deals with one set of input devices, those that can be manipulated by one user at a time Multi-user operating system deals with input, output, and processing requests from many users , all at the same time

Operating System
Are different operating systems needed for different computing tasks?

Network operating system provides communications and routing services that allow computers to share data, programs and peripheral devices Multitasking operating system provides process and memory management services that permit two or more programs to run simultaneously

Operating System
Are different operating systems needed for different computing tasks

Desktop operating system designed for a personal computer, either a desktop or notebook computer designed to accommodate a single user, but may also provide networking and multitasking capabilities

Windows, MAC OS, Linux, UNIX and DOS
What’s the best-selling operating system?

Windows, MAC OS, Linux, UNIX and DOS
Is Mac OS similar to Windows? Both operating systems base their user interfaces on the graphical model that was originated at Xerox PARC, although Mac OS was developed several years before Windows Mac and Windows interfaces use a mouse to point and click various icons and menus Are UNIX and Linux the same? UNIX, developed in 1969 at AT & T’s Bell Labs, gained a good reputation for its dependability in multi-user environments Linux was developed in 1991, based on a version of the UNIX kernel called Minix Linux is considered to be a popular operating system for e-mail, web-servers and local area networks

Windows, MAC OS, Linux, UNIX and DOS
Why do I keep hearing about DOS? stands for Disk Operating System it provides part of the operating system kernel for Windows versions 3.1, 95, 98 and ME users rarely interact with DOS, because it is well hidden by the Windows graphical user interface

Software
Software: can be divided into: systems software or system programs applications software or application programs Types of Computer Software

Functions of an Operating System
Operating Systems collection of system programs and routines that reside in the computer’s memory functions: • Schedule input and output operations • Schedule work of jobs according to priority • Communicate with the human operator • Handle interruptions and monitor system status • Log the jobs that are finished and currently being executed • Control system access and data security functions • Facilitate in locating and debugging errors • Handle multiprogramming, so that several programs can run at the same time

Functions of an Operating System
Operating Systems stored in a secondary storage device known as a system residence device in the early days when magnetic tape drives are still used as storage devices, operating systems that are stored in magnetic tapes are called Tape Operating Systems if the operating system is stored in a magnetic disk it is called a Disk Operating System (DOS)

Structure of an Operating System

Programs that Make Up an Operating System
Control Programs - manage the overall system operations and perform tasks such as scheduling, input/output handling, monitoring of system status and communication with the programmer • Supervisor Program • Input/Output Control System Service Programs - are subprograms or routines that are frequently used by the programmer • Language Translator Programs • Librarian Programs • Utility Programs • Diagnostic Programs

Survey of an Operating System
MS-DOS The Windows Family of Operating Systems • Windows 1.0, 2.0, 3.1 and 3.11 • Windows NT and Windows 2000 • Windows 95, 98, ME and XP UNIX and Linux

Survey of an Operating System
What’s the best-selling operating system?

Microsoft Windows is being used on over 80 percent of the world’s personal computers. Windows has evolved through several versions, since its introduction.

Survey of an Operating System

Survey of an Operating System
What’s the best-selling operating system?

Windows 95, Windows 98, Windows ME and Windows XP provide basic networking capabilities, making them appropriate for small networks in homes and businesses. Windows NT, Windows 2000, and Windows XP Professional are typically classified as server operating systems.

Survey of an Operating System
Is Mac OS similar to Windows? Both operating systems base their user interfaces on the graphical model that was originated at Xerox PARC. Both Mac and Windows interfaces use a mouse to point and click various icons and menus. Both also provide basic networking capabilities. Though the selection is not as vast as the collection of Windows, a collection of software is available for computers that run Mac OS.

Survey of an Operating System
Are UNIX and Linux the same?

UNIX gained a good reputation for its dependability in multi-user environments. Many versions of UNIX became available for mainframes and microcomputers. Linux is distributed under the terms of a General Public License (GPL), allowing everyone to make copies for their own use, to give others, or to sell.

Survey of an Operating System
Are UNIX and Linux the same?

Linux shares several technical features with UNIX. Linux is considered to be a popular operating system for e-mail , web-servers and local area networks. Linux has been gaining popularity as a desktop operating system.

Survey of an Operating System
Why do I keep hearing about DOS? DOS was the first operating system and its cryptic command-line user interface left an indelible impression. The remnants of DOS still linger in the world of personal computers, because it provides part of the operating system kernel for Windows versions 3.1, 95, 98 and ME. Users rarely interact with DOS, because it is well hidden by the Windows graphical user interface. DOS is nothing more than footnotes in the history of the computer industry.

Application Software
An Overview of Application Software Word Processing a term used in manipulating text or words in a file Basic features:
insert text delete text cut and paste copy page size and margins search and replace word wrap Print

Advanced features:
file management font specifications footnotes and cross-references graphics headers, footers, and page numbering layout merges spell checker tables of contents and indexes thesaurus windows

WYSIWYG

Application Software
Microsoft Word

Application Software
Spreadsheet computer programs especially designed to display information graphically and allow files and data to be manipulated easily an electronic ledger sheet on which data are entered

MS Excel Spreadsheet Program

Application Software
Database Management application software packages that computerize the everyday task of recording, processing, filing, and manipulation of information in the database Database : a collection of information organized in such a way that a computer program can quickly select desired pieces of information (or data); like an electronic filing system Basic features: To add or delete information within a file To search a file for some information based on some criteria To update information from within a file To sort information into some order To generate a printout or reports

Application Software
Graphics Software Packages designed to allow the user to display images on a computer monitor or to print the images on a printer Examples of graphic applications: paint programs illustration/design programs presentation graphics software animation software CAD software desktop publishing

Installation Basics
Installation Process Copy files from distribution disks to specified folders on the hard disk. If the files have been distributed in a compressed format, uncompress them. Analyze the computer’s resources, such as processor speed, RAM capacity, and hard disk capacity. To select appropriate device drivers, analyze hardware components and peripheral devices. Look for any system files and players, such as Windows Media Player or Internet Explorer, which are required to run the program, but not supplied on the distribution disks. Update necessary system files, like Window Registry and the Windows Program menu, with information about the new software.

Installation Basics
Are all of the files for the software provided on the distribution disk Application software programs share some common files, through the use of Windows and other operating systems. Because these files should already exist on your computer, the “shared” files are not typically provided on the distribution disks for the new software program. The installation process attempts you to locate these files, and will notify you if any of them are missing.

Installing from a Distribution Disk to CD
Video Capture Software Installation Process Insert the distribution disk, CD, or DVD. Read the license agreement, if one is presented on the screen. You will be prompted to select between full and custom installation. Choose the installation option that best meets your needs. Follow the instructions provided by the setup program to specify a folder to hold the new software program. If the software includes multiple distribution disks, insert each one in the specified drive when the setup program tells you to do so. When the setup is complete, begin the program that you just installed to make sure it works.

Installing Downloaded Software
Compressed file types for downloaded software Manual download and install Downloaded files with a .zip extension must be located on the hard disk. Must use a program such as WinZip to unzip it. To acknowledge the license agreement, the setup program must be executed. Specify the folder for the software files, and complete the installation. Self-installing executable file Follow the setup program prompts to acknowledge the license agreement. his self-installing executable file automatically unzips itself and starts the setup program. Specify the folder for the software files, and complete the installation.

Installing Downloaded Software
Compressed file types for downloaded software Self- executing zip file These files automatically unzip the software’s files but do not automatically start the setup program. To unzip the files for the new software, the executable file must be started. Start the setup program manually and follow its prompts to complete the installation

Uninstalling Software
You can remove software, with some operating systems, such as DOS by simply deleting its files. With Windows and Mac OS, uninstall routine is provided to delete the software’s files from various directories on the computer’s hard disk. You can normally find the uninstall routine with Windows software, on the same menu as the program. In Windows, the Add/Remove Programs icon can be found in the Control Panel, accessible from the Start menu.

Software Copyrights
Copyright a form of legal protection that grants the author of an original ”work” an exclusive right to copy, distribute, sell and edit that work, except under special circumstances described by copyright laws Exceptions The purchaser can make a backup or extra copy of the software in case the original copy becomes erased or damaged is allowed to copy and distribute parts of a software program for use in critical reviews and teaching has the right to copy software from a distribution disk or Web site to a computer’s hard disk in order to install it

Software Licenses
License Agreement a legal contract that defines the ways in which a computer program may be used can be found on the outside of the package, on a separate card inside the package, on the CD packaging, or in one of the program files Techniques to validate software license shrink-wrap licenses installation agreements

Software Licenses
Questions to be Considered When Reading a Software License Agreement When does the license go into effect ? Can I sell the software ? Can I rent the software ? Am I buying the software or licensing it ? Can I loan the software to a friend ? Does the software publisher provide a warranty ? Under what circumstances can I make copies ?

Software Licenses
Public Domain Software may be freely copied, distributed and even resold not protected by copyright because the copyright has expired, or the author has placed the program in the public domain, making it available without restriction Commercial Software usually sold in computer stores or at Web sites adheres closely to the limitations provided by copyright law it might give you permission to install the software on a computer at work and at home, but you have to use only one of them at a time

Software Licenses
Freeware a copyrighted software that is available for free does not allow you to modify it or sell it, but it allows you to use the software, copy it and give it away utility programs, some games and device drivers Shareware a copyrighted software marketed under a “try before you buy” policy, allowing you to use the software for a trial period usually permits you to copy and distribute it to others provide a low-cost marketing and distribution channel

Software Licenses
Open Source Software may be sold or distributed free of charge uncompiled program instructions are available to programmers who want to alter and improve the software Linux, FreeBSD

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