think possibility unit 1.1: computer systems-basic computer model computer definition: a device that...

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Unit 1.1: Computer Systems-Basic Computer Model

Computer Definition:• A device that accepts input, processes data, and produces output, all according to a series of stored instructions• Been called “mind tools”• 1940-modern definition and use of the term “computer” emerged when the first electronic computing devices were developed as a response to World War II military needs.•1945- team of engineers began working on a secret military project to construct the Electronic Discrete Variable Automatic Computer (EDVAC)

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Basic Computer Model

All computers, no matter how large or how small, perform four basic operations:

• Input• Processing• Storing results• Output

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A Computer Accepts Input

• Computer input is whatever is put in a computer system

• The word “input” is a verb that means to feed information into a computer

• What kinds of input can a computer use? 1. Person 2. Environment 3. By another Computer

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• Person

This is the most common way on how a computer accepts its input. A person (aka User) supplies the instructions or data for a computer to process a certain task.

A Computer Accepts Input

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• Environment

Computers may also receive its input based on the environment (e.g computers on a car assembly line). Military also use this kind of input on their missiles for accurate hits.

A Computer Accepts Input

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• By another Computer

Its also possible to accept inputs from another computer. Like a network setup (like the internet) a computer may receive inputs based on a query.

A Computer Accepts Input

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A Computer Accepts Input

Input Device-gathers input and transforms it into series of electronic signals for the computer.

• Keyboard• Mouse• Scanner• Touch screen pad• Gaming products (gamepad, dancepad)

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A Computer Processes Data

In what ways can a computer process data?

Data – refers to the symbols that represent facts, objects, and ideas

Processing-manipulation of data by the computer

Computer Program-series of instructions that tells a computer how to carry out processing tasks

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A Computer Processes Data

Some ways that a computer can process data:

•Performing Calculations•Sorting•Modifying Documents and Pictures•Drawing graphs and etc.

Central Processing Unit (CPU)-most processing takes place, also described as the “brain of the computer”

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A Computer Stores Data

Why does a computer store data?

A computer must store data so that it will be available for processing.

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A Computer Stores Data

• Memory – is an area of a computer that holds data that is waiting to be processed. It is an area of a computer that temporarily holds data that is waiting to be processed, stored or output.

• Storage - is the area where data can be left on a permanent basis while it is not needed for processing.

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A Computer Stores Data

What’s so significant about a computer’s ability to store programs?

Stored programs will make processes much simpler. It will not require you to perform the same instructions.

Stored Program-series of instructions for a computing task can be loaded into a computer’s memory.

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A Computer Produces Output

What kinds of output does a computer produce ?

Computer output is the results produced by the computer.

Output is a verb that means the process of producing output

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A Computer Produces Output

Examples of Computer Output:

• Reports• Documents• Music• Graphs• Pictures

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A Computer Produces Output

Output Device-displays, prints, or transmits the results of the processing

• Printer• Monitor

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Basic Computer Model

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Software

Why does a computer need software?

Software sets up a computer to do a particular task, tells the computer how to interact with the user, and specifies how to process the user’s data.

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System Components

When I use a Computer System, what hardware components will it include?

• System Unit• Monitor• Floppy Disk Drives• CD-ROM / DVD-ROM• Hard Disk Drive• Keyboard• Mouse

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Categories of Computers

Why is it useful to categorize computers?

• Computers are versatile machines• It is a way of grouping them according to criteria: usage, cost, size, and capability

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Categories of Computers

• Microcomputers• Minicomputer• Mainframes• Supercomputers

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Microcomputers

• It is also known as personal computers.• It is typically found in homes and small businesses It is designed to meet the computing needs of an individual. • It is consisted of a single chip called a “microprocessor

Types of Microcomputers:• Desktop Computers• Notebook Computer• Personal Digital Assistant

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Desktop Computer

• It fits on a desk and runs on power from an electrical wall outlet

• The main unit can be housed in either a vertical case or a horizontal case.

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Notebook Computer

• It is small and lightweight

• It can run on power supplied by an electrical outlet or battery power

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Personal Digital Assistant

• It is designed to fit the pocket, run on batteries, and be used while you are holding it

• It is used as an electronic appointment book, calculator, address book, and notepad.

• It is not powerful enough to handle many tasks

• It is designed to be a computing accessory

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Minicomputer

• It is used to describe a second computer category.• It is smaller, less expensive, and less powerful than mainframes. • More powerful than a microcomputer and can carry out the processing tasks for several people working at terminals that are connected to the minicomputer.

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Minicomputer

Processor

64-bit POWER3-II Clock rates (Min/Max)

333 MHz / 400 MHz / 450 MHz System memory (Std/Max)

256MB / 2GB Internal storage (Std/Max)

18.2GB / 293.6GB

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Minicomputer

Processor

64-bit POWER3-II (4 – 32 Way) Clock rates (Min/Max)

450 MHz – 1.3 Ghz System memory (Std/Max)

2GB – 256 GB Internal storage (Std/Max)

18.2GB / 873.6GB

IBM RS6000

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Mainframe Computer

• It is a large, fast, and expensive computers, generally used by government to provide centralized storage, processing and management for large amounts of data• Its price typically starts at several hundred thousand dollars and can exceed a million dollars.

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Mainframes

Parallel SysplexLarge Scale Performance ReferenceCopper Chip technology(12 – Way)

IBM S/390

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Supercomputers

• It is defined simply as the most powerful class of computers at any point in time.• It is one of the fastest computers in the world.• Due to its speed, it can tackle complex tasks.

Uses of Supercomputers:• Breaking Codes• Modeling Worldwide Weather Systems• Simulating Nuclear Explosions

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Supercomputers

CRAY SV-1

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Microcomputer Compatibility

• Two computer platforms are compatible if they can share the same software and use the same peripheral devices.

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Peripheral Devices

• The term “peripheral device” designates equipment that might be added to a computer system to enhance its functionality.

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Unit 1.2: File Systems

A file system is a software abstraction for organizing data on mass storage media such as hard drives, floppy disks, and optical disks. The Microsoft Windows file system supports four kinds of entities: files, folders, drives, and shortcuts.

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Computer Files

What kinds of files are stored on a computer?

File – is a named collection of data that exists on a storage medium such as a hard disk, a floppy disk, or a CD.

•Program•Data

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File Naming Conventions

Filename – is a unique set of letters and numbers that identifies a file and usually describes the file contents.

A filename might be allowed by a filename extension that further describes the file contents

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File Naming Conventions

DOS and Windows 3.11

Windows 95/98/NT/2000

MacOs Unix / Linux

Maximum Length of filename

8 filename3 extension or less

255 filename3 extension or less

31 characters no extension

14-256 characters (depending on version)Extension of any length

Spaces allowed

No Yes Yes No

Numbers Allowed

Yes Yes Yes Yes

Characters not allowed

/ [] ; = “ \ : , | * ?

\ ? : “ < > | * / None ! @ # $ % ^ & * () {} [] “ \ ‘ ; < >

Filenames not allowed

Aux, Com1, Com2, Com3, Com4, Con, Lpt1, Lpt2, Lpt3, Prn, Nul

Aux, Com1, Com2, Com3, Com4, Con, Lpt1, Lpt2, Lpt3, Prn, Nul

None Depends on the version of Unix or Linux

Case Sensitive

No No Yes Yes (use lowercase)

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Folders

Files live in folders, which are also sometimes called directories. Folders have names and properties too. And like files, every folder has a home: it lives in another folder called its parent. This gives the file system a hierarchical structure, like a family tree. The top of the folder hierarchy is called the root.

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Drives

Drive designators like A: and C: refer to specific physical devices, normally a floppy drive in the case of A: and a hard drive in the case of C:.

It is possible to partition a hard disk drive into several logical segments called partitions, so that C:, D:, and E: refer to separate portions of the same physical device.

Network drives (disk drives located on another computer and accessed via a local network) may have logical designators too, such as M: and N:. Each logical drive has its own directory hierarchy, starting at the root.

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Paths

Since items in different folders can have the same name and folders can be nested within other folders, we need a way to unambiguously tell the operating system or an application exactly which object (that is, which file or folder) we mean. We can do this by specifying the path to the object.

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Shortcuts

A shortcut is an alternate way to reach a file. Shortcuts have names and live in folders just the way files do. But a shortcut doesn't actually hold any data. Instead, it has a shortcut property that specifies the path to the file where the data can be found. This file is called the target of the shortcut. The target can be anywhere, even on a different drive. A shortcut only refers to its target; it is not a copy of the target. So when you open a shortcut and edit what you find there, you are actually editing the target file.

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Recycle Bin

Somewhere on your desktop is an icon that looks like a waste bin or trash can. Windows calls this the "Recycle Bin." One way to delete a file is to use the mouse to drag the file's icon over to the Recycle Bin; when you release the mouse button, the file icon disappears. However, the file is not really gone; it's just been moved to a special folder and "hidden" from view.