Lecture-4 / T. Nouf Almujally
1

• • •
History (Homework) Types of Computer Systems.
The computer System Concept.
•
• • • Input Technologies.
Output Technologies.
Storage Technologies.

Called a personal computer or PC Computing power now exceeds that of the mainframes of previous generations Relatively inexpensive Desktop, Hand-held, notebook, laptop, tablet, portable, and floor-standing Home , personal , professional , workstation or multiuser systems.

Workstations
- Supports heavy mathematical computing and graphics display demands Ex: - CAD in engineering, - Portfolio analysis.
Network Servers
- More powerful than workstations - Coordinates telecommunications and resource sharing - Supports LAN and Internet.

• •
a computer.
is any input/output device connected by a network to
1.
2.
Dumb terminals: keyboard and video monitor with limited processing capabilities.
• Intelligent terminals: networked PCs that perform data entry and other information processing tasks.
Transaction terminals : • Use keyboards, touch screen, bar code scanners to capture data , while relying on servers in the network for further transaction processing.
• ex in banks, ATMs machines, airport check-in, POS.

3.
• • Network terminals: Windows terminals: depend on network servers for Windows software, processing power and storage.
Internet terminals: depend on the Internet/Intranet servers for their operating systems and application software.

• Hand-held microcomputer devices, known as personal digital assistants (PDAs).
   Web-enabled PDAs use touch handwriting recognition, or keypads.
screens, pen-based Mobile workers use to access email or the Web, exchange data with desktop PCs or Web servers.
Latest entrant is the RIM BlackBerry, Apple iPhone.
• • • Information Appliances may also take the form of: Video-game consoles and other devices that connect to your home television set. Enable you to surf the WWW, email, play.
Telephone-based home appliances that access the web.

• High-end network servers that handle large-scale processing of business applications.
  Not powerful as mainframes.
Less expensive to buy, operate, maintain than mainframes.
• First became popular as minicomputers for scientific research and industrial process monitoring.
•
Today used in:
  Computer-aided manufacturing (CAM).
Used as front-end servers to assist mainframes in telecommunications processing and network management.

• Large, fast, powerful computer systems  Large primary storage capacity.
  High transaction processing Handles complex computations •
Used to:
   Handle the information processing of major corporation and government agencies with high transaction processing.
As a superservers for the large client/server networks and high volume Internet websites for large companies.
Becoming a popular computing platform for: Data mining, warehousing, electronic commerce applications

• Extremely powerful computer systems designed for scientific, engineering and business applications requiring extremely high speeds for massive numeric computations.
• Markets for supercomputers include:    Government research agencies.
Large universities.
Major corporations.
• Used for global weather forecasting, military defense, astronomy.
• • Billions to trillions of operations per second.
Millions of dollars.

• A computer system is an interrelated combination of components performing basic functions to provide end users with a powerful information processing tool.
Input Control Computer System Processing Storage Output

• • • Early computers Milliseconds (thousandths of a second) Microseconds (millionths of a second) • • • Current computers Nanoseconds (billionth of a second) Picoseconds (trillionth of a second) • • • Program instruction processing speeds Megahertz (millions of cycles per second) Gigahertz (billions of cycles per second) • Commonly called “clock speed”

Peripheral Online Devices Offline Devices
Generic name for all input, output, and secondary storage devices Depend on direct connections to the CPU of a computer system All online devices Separate from the CPU, but electronically connected to (and controlled by) it Separate from, and not under the control of, the CPU

• • Common input devices: Keyboard.
•
• • • • Examples: Electronic mouse and trackball.
Pointing stick Touch pad.
Touch screen.

•
Used in Tablet PCs and PDAs  They have a Pressure-sensitive layer, similar to touch screen, under liquid crystal display (LCD) screen.
  Software digitizes handwriting, and hand drawing.
Examples: Graphics Tablet, Digitizer.

•
Speech Recognition:
Speech may be the future of data entry because it’s the easiest, most natural means of human communication.
• Recognizing speech patterns: • Discrete speech recognition: requires pauses between each word.
• Continuous speech recognition (CSR) recognizes continuous speech.

• Speech recognition systems digitize, analyze, and classify your speech and its sound patterns: • • • Compares your speech patterns to a database of sound patterns Passes recognized words to your software Speech recognition SW requires voice recognition training •
• • Allow computers to recognize words from a voice never heard before Used in voice-messaging computers, computerized telephone call switching.

Sheet-fed scanner Flatbed scanner Optical scanner, copier, fax & printer
• • Devices read text or graphics and convert them into digital computer input.
Enables direct entry of data from source documents into a computer system.
• Document management library system • Scans documents, then organizes and stores them for easy reference or retrieval.

Scanners Compact desktop models are popular for low cost and ease of use Larger, more expensive flatbed scanners are faster, offer high-resolution color scanning Optical Character Recognition (OCR) Software that reads characters and codes Used to read product labels, airline tickets, score tests, read bar codes

• • Magnetic stripe Read magnetic stripe on credit cards • • Smart cards Microprocessor chip and memory .
• • Digital cameras Digital Camcorder.
• • Magnetic Ink Character Recognition (MICR) Identification numbers of bank and account printed in magnetic ink on bottom of check .

Voice Response Video Displays Printed Output Increasingly found along with video displays in business applications Cathode-ray tube (CRT) Liquid crystal display (LCD) Plasma displays Inkjet , laser, multifunction model

Uses two-state binary data representation Bit Byte Data processed & stored in computer systems through presence or absence of signals , Either ON or OFF On (1) or Off (0) Smallest element of data Either 0 or 1 Group of eight bits, which operate as a single unit Represents one character or number

Kilobyte (KB) Megabyte (MB) Gigabyte (GB) Terabyte (TB) Petabyte (PB) One thousand bytes One million bytes One billion bytes One trillion bytes One quadrillion bytes

• Direct Access or Random Access • Directly store and retrieve data.
• Each storage position has unique address and can be accessed in same length of time.
• Semiconductor memory chips, magnetic disks.
• Sequential Access • Data is stored and retrieved in a sequential process.
• Must be accessed in sequence by searching through prior data.
• Magnetic tape.

• • The primary storage (main memory) of your computer consists of microelectronic
“semiconductor memory “
chips.
• • It provides you with the working storage your computer needs to process your applications.
Advantages:
small size, fast, shock and temperature resistance
Disadvantages:
volatility; must have uninterrupted electric power or the contents of the memory will be lost.
 or permanently “burn in” the contents so they cannot be erased by a loss of power.

Random Access Memory (RAM)
1. Most widely used primary storage medium 2. Volatile memory 3. Read/write memory
Read-Only Memory (ROM) Flash Drives “Jump Drive”
1. Permanent storage 2. Can be read, but not overwritten 3. Frequently used programs (parts of OS) burned into the chips during manufacturing 4. Called firmware 1. New type of permanent storage, can store data for unlimited periods without power.
2. Easily transported 3. Plugs into any USB port.

• Used for secondary storage • Fast access and high capacity • Reasonable cost • • Hard Disk Drives & Floppy Disks (diskettes)
Types of Magnetic Disks: Floppy disks
 A single magnetic disk inside a plastic jacket
Hard disk drives
 Magnetic disks, access arms, and read/write heads in sealed module.

•
RAID (Redundant arrays of independent disks)
    Disk arrays of interconnected hard disk drives.
They combine from 6 to more than 100 hard disk drives into a single unit.
Provide large capacities (1-2 TB or more).
Provide fault tolerant with multiple copies on several disks  Storage area networks (SANs) are high speed fiber channel local area networks that can interconnect many RAID units and thus share their capacity through network servers with many users .

Tape Reel Tape Cartridge
• • • •
Include Tape reels, and cartridges (larger capacity).
Lower-cost storage solution Used for: long term archival and backup storage

Image Processing Publishing Medium Interactive Multimedia Applications in business Long-term storage of historical image files Storage of scanned documents Allows fast access to reference materials Catalogs, directories ,manuals and so on Multimedia encyclopedias, Video games, educational videos, and so on