Output devices

Monitor or screen• Text

• Numbers

• Symbols

• Art

• Photographs

• Video

Printer• Black and white

• Color

• Convert from electronic form to some other form

• May display the processed results• Usable information

Output Devices

Output devices make the information resulting from the processing available for use. The two output devices are as follows:

• Printer• Monitor

PrinterThe printer produces a hard copy of your output, and the computer screen produces a soft copy of your output.

Output Devices

Monitor• There are two basic types of monitors: • CRT (cathode ray tube) monitors• LCD (liquid crystal display) monitors.

• Both types produce sharp images, but LCD monitors have the advantage of being much thinner and lighter. CRT monitors, however, are generally more affordable

The Processor

Central Processing Unit (CPU)

• Converts data to useful information

• Interpret and execute instructions

• Communicate with input, output and storage

Motherboard

• The motherboard is the computer's main circuit board.

• It's a thin plate that holds the CPU, memory, connectors for the hard disk drive and optical drives, expansion cards to control the video and audio, as well as various external ports and peripherals.

• The motherboard connects directly or indirectly to every part of the computer.

Computer Memory

• Computer Memory are internal storage areas in the computer .

• used to either temporarily or permanently store data or instructions to be processed.

Computer Memory

Memory

Internal Memory

Volatile Memory

RAM

Non-Volatile Memory

ROM

External Memory

Sequential Access

Tape Drive

Random Access

Compact Disk Hard Disk Flash Disk

/Floppy Disk

Volatile Memory

Loses its contents when the computer's power is

turned off

volatile memory

Loses its contents when the computer's power is

turned off

What are the two types of memory in the system unit?

nonvolatile memory

Does not lose its contents when the

computer’s power is turned off

Memory

Also called primary storage and main memory,

chips that temporarily holds software instructions and data before and after it is processed by the CPU.

RAM is the working memory of the computer.

What is random access memory (RAM)?

What is read-only memory (ROM)?

BIOS

(basic input/output system)

Stored on ROM

Sequence of instructions the computer follows to

load the operating system and other files when you first turn on the computer

Nonvolatile — Contents not lost

when the computer is turned off

Memory chips that contain data, instructions, or information that is recorded permanently

Data can only be read,

cannot be modified

11

Memory also called Random Access Memory or RAM (temporary memory) is the main memory of the computer. It consists of electronic components that store data including numbers, letters of the alphabet, graphics and sound. Any information stored in RAM is lost when the computer is turned off.

Read Only Memory or ROM is memory that is engraved on a chip that has start-up directions for your computer. It is permanent memory.

Memory

Two Types of Storage

• Secondary storagelong-term storage

• Primary storage or memorytemporary storage

Storage Devices

Primary Storage Devices

• Also known as internal memory and main memory.• The fastest type of memory in your computer and is used to

store data while it's being used.

• Computer RAM and cache are both examples of a primary storage device.

• For example, when you open a program data is moved from the secondary storage into the primary storage.

• Unless this information is saved to a Secondary Storage Device, it will be lost when the computer is powered down.

Storage Devices

RAM (Random Access Memory)• Computer’s short-term memory.• Data is temporarily stored here until you

save your work to the hard disk.

• RAM is used by the system to store data that is processed by a computer's CPU.

• RAM is a volatile memory and requires power; if power is lost, all data is also lost.

Secondary Storage Devices

Secondary Storage Devices

Also known as external memory and auxiliary storage, secondary storage

• Used to store data when they are not being used in memory.

• The most common types of auxiliary storage used on personal computers are:• floppy disks, hard disks, CD-ROM drives, USB

Secondary Storage Devices

Floppy DisksA portable, inexpensive storage medium that consists of a thin, circular, flexible plastic disk with a magnetic coating enclosed in a square-shaped plastic shell.

Initially Floppy disks were 8-inches wide, they then shrank to 5.25 inches, and today the most widely used floppy disks are 3.5 inches wide and can typically store 1.44 megabytes of data.

Structure Of Floppy Disks

Initially Floppy disks were 8-inches wide, they then shrank to 5.25 inches, and today the most widely used folly disks are 3.5 inches wide and can typically store 1.44 megabytes of data.

A folly disk is a magnetic disk, which means that it used magnetic patterns to store data.

Data in floppy disks can be read from and written to. Formatting is the process of preparing a disk for

reading and writing. A track is a narrow recording band that forms a full

circle on the surface of the disk.

Structure Of Floppy Disks

• The disk’s storage locations are divided into pie-shaped sections called sectors.

• A sectors is capable of holding 512 bytes of data.• A typical floppy stores data on both sides and has

80 tracks on each side with 18 sectors per track.

Secondary Storage Devices

Hard Disks• Consists of one or more rigid metal plates

coated with a metal oxide material that allows data to be magnetically recorded on the surface of the platters.

• The hard disk platters spin at a high rate of speed, typically 5400 to 7200 revolutions per minute (RPM).

• Storage capacities of hard disks for personal computers range from 10 GB to 120 GB.

Secondary Storage Devices

Compact Discs (CD)• Also called an optical disc, is a flat round,

portable storage medium that is usually 4.75 inch in diameter.

• Standard CD can hold 700MB of data, around 80minutes of CD quality audio, or up to 60minutes of video.

• The later standard called the DVD (Digital Versatile Disc) is still an optical media much like the CD but with much greater capacities, starting at 4.7GB at the low end to as high as 17GB.

Secondary Storage Devices

USB Drive (Universal Serial Bus)• Also known as a flash drive or keychain

drive.• It is a plug-and-play, portable storage

device.• can be used in place of a floppy disk, Zip

drive disk, or CD.

• Available in capacities ranging up to about 65 GB.

Put all the hardware together and…

Types of Computers

• Depending upon their speed and memory size, computers are classified into following four main groups.

• Supercomputer. • Mainframe computer. • Mini computer. • Microcomputer

Supercomputers

• High-capacity machines with hundreds of thousands of processors that can perform over 1 trillion calculations per second.  E.g IBM ASCI White, Cray

• Used where High Performance computing is required• Usually used for weather forecasting, Missile

simulations, Nuclear Fusion simulations

IBM ASCI White

IBM ASCI White

Mainframes

• Water- or air-cooled computers that vary in size from small, to medium, to large, depending on their use.

• E.g IBM AS/400• Normally Dumb Terminals are

connected to these main frames. Processing is done by Main Frames

• Dumb terminals only have keyboard, monitors

VP2400 mainframe

Workstations• Expensive, powerful

computers usually used for complex scientific, mathematical, and engineering calculations and for computer-aided design and computer-aided manufacturing.

• e.g. Sun blade 2500

Sun Microsystems workstation

Microcomputers

• A Desk Top Personal Computer• Your home computers… Celeron• Now Desktop and Workstations are combining. i.e Your

PC is also becoming powerful enough

Microcomputers

Sony tower PC

• A Tower Case Personal Computer

Microcomputers

• A Lap Top Personal Computer• Lightweight portable computers with built-in monitor,

keyboard, hard-disk drive, battery and AC adapter.

Microcomputers

• A Personal Digital Assistant• Getting Very popular

• Personal organization tools-schedule planners, address books, to-do lists, send e-mail and faxes.

• New generation that incorporates mobile phone and microcomputer.

• HP 5555

Thank You