Computer Systems Hardware - System Unit Software - Operating System Peripherals...

Computer SystemsComputers are useful machines, but they are generally useless by themselves. Computers are usually part of a system – a computer system includes:• Hardware (machines)• Software (programs, applications)• Communication (networks, radio links)• Meatware (people, users – don’t forget them)

Computer Systems Hardware - Peripherals Platforms Developments System Unit - Storage Data Architecture Software - Operating System Utilities Apps Processing Types Communication - LAN WAN People

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Computer hardware includes many components.

The traditional view is divided into 4 sections:

Hardware

Storage

Processing

Input

Output

CPUPeripherals

Input Storage Processing Output


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PeripheralsPeripherals are the devices attached to the CPU.Some are input devices, others are output devices. They are commonly attached to a USB port (Universal Serial Bus). Some common peripherals are:

Monitor (VDU, CRT, LCD)Printer , PlotterSpeaker (music, warnings)LED (light emitting diode)Motors (robots, machines)------------------------------------Force-Feedback JoystickSmart Board, Touch Screen

Keyboard , Mouse Scanner (OCR), Graphic TabletLight Pen , Bar-Code ReaderOptical Mark RecognitionMagnetic Ink Character Recog.Digital Camera, Video CameraSensors (temperature, light)Microphone (voice recognition)Joystick (game pad), VR Glove

OutputInput

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http://www.ib-computing.com/program/core/peripherals.html

System UnitThe System Unit contains the motherboard, disk-drives, power supply, and ports (connectors). In a PC, all these things are contained inside the box.We divide the contents into two areas:

Processing mainboard, bussesmicroprocessorcontroller chips, cache

Storage RAM, ROM, flash disk drive(s) tape drive


StorageStorage is divided into 2 types:• Primary Memory – RAM, ROM, cache – contains programs and data being used currently, and is directly accessible to the CPU• Secondary Storage – disk, tape, flash memory – permanent storage for software and data, access requires I/O operations • Backup – extra storage, usually not directly accessible – requires mounting the media – includes robotic warehouses and networks

3.2.5-6


http://www.ib-computing.com/program/core/memories.html

http://en.wikipedia.org/wiki/Computer_storage

Data Representation

Data is stored as digital numbers. These are stored in binary (1’s and 0’s) using transistors and other bipolar devices. The following issues are important:• number systems – binary, hexadecimal

• bits and Bytes – kilo, mega, giga, tera

• analog vs digital – ADC, DAC, sampling

• error detection – parity bit, check-sum

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3.2.2

3.5.6-8

3.6


http://www.ib-computing.com/program/core/representation.html

http://www.ib-computing.com/program/core/representation.html

http://www.ib-computing.com/program/core/analog_digital.html

http://www.ib-computing.com/program/core/errors.html

ArchitectureArchitecture describes the most basic features and functions of a computer. A 32-bit architecture means that all the busses and chips can process 32-bits of data at a time. Architecture issues include:• Microprocessor (CPU) – Pentium, AMD, Motorola • Word-Size & Bus-Width – 32-bit, 64-bit • Speed – MegaHertz, GigaHertz• Band-width – bits-per-second (bps)• Memory Size – MegaBytes, GigaBytes• Motherboard – contains all the chips, including the controller chipset

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3.2.7


http://www.ib-computing.com/program/core/architecture.html

http://www.informit.com/articles/article.asp?p=130978&seqNum=4&rl=1

http://www.karbosguide.com/books/pcarchitecture/chapter04.htm

http://www.ib-computing.com/program/core/architecture.html

PlatformsComputers come in many different sizes and shapes, for different tasks (applications):• Personal Computer (PC) – for office work, personal use, public terminals, for single user• Mainframe – big expensive machines for large databases, accessible by many users• Portable - very small, battery powered, limited storage, portable data access communication• Supercomputer – usually large, very expensive, very fast calculations for scientific simulations

3.3.3-4


http://www.ib-computing.com/program/core/operatingsystems.html

DevelopmentsThe history of the digital computer is less than 70 years old. New technologies develop at exponential speeds – according to Moore’s Law, computer power is doubling every 18-24 months. Reasons include:• parallel processing – parallel pipelines, dual-core processors• reduced circuit size – portable devices, increased transistor density• new technologies – optical storage, flash memory• expansion – wireless communications, global networks

3.2.9


http://www.ib-computing.com/program/core/recent.html

SoftwareSoftware is programs and applications controlling: • user-interface (operating system)

• hardware drivers (for peripherals)

• calculations (processing data)

• logic of operations (business rules)


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Operating SystemThe OS provides an interface between the hardware devices and the software. Common examples are: Windows, Linux, Unix, Mac OS

A modern OS provides:• hardware control (interrupts, device drivers)• software execution (load and run programs)• User Interface (command line, GUI)• resource allocation (disk & memory management)• multi-tasking (task manager)• communication service (interrupts, LAN, WAN)• security (accounts, passwords)

3.3.1-2


http://www.ib-computing.com/program/core/operatingsystems.html

UtilitiesModern OS’s include utilities for adjusting and improving operations, including:• file maintenance – search, copy, delete, etc• backups – automatically make backup copies• disk maintenance – format, partition, defragment• compression – archives (.zip)• security – account and password management, virus scanner

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http://www.ib-computing.com/program/core/utilities.html

ApplicationsRecall that a computer system includes people. The users have reasons (goals) for using the system.

They accomplish tasks for specific applications.Some common application areas are:

• network apps – e-mail, browser, conferencing, e-commerce• word-processing (secretaries, office-workers)• inventory management (stores, warehouses)• banking (money and property records)• games and entertainment• scientific research and simulation• machine control (airports, hospitals, factories)

3.4.9


http://www.ib-computing.com/program/core/netapps.html

Types of Processing

Not all computer systems work like a PC. PC applications use interactive processing – the user is directly involved all the time. We identify 3 different processing types:• Interactive (online) – the user is involved all the time – word-processing, web-browsing, games, streaming video• Batch processing – data is collected over time and submitted in a big batch, all at once – bank cheques, backups, downloading music or programs• Real-time – the computer controls machines or reacts to sensors at the same speed as the real world – robots, air-traffic control, medical sensors, live broadcasts ** Reliability is an important issue and may effect the choice of processing type.

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http://www.ib-computing.com/program/core/processing_types.html

http://www.ib-computing.com/program/core/reliability.html

CommunicationEarlier computer systems were stand-alone – they existed in one place and functioned in isolation. Now communication is normal for computers, through networks and wireless links, including:• LANs (intranets, home networks)• WANs (Internet, large business networks)• Telecommunications (phones, broadcasts)

• Multimedia (video, audio)


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LANLocal Area Networks use cables (or wireless) to connect lots of workstations (PCs), servers, and peripherals (printers, scanners, etc). This allows many users to share data and peripheral devices.The architecture (organization) of the LAN involves:• topology – bus, star, ring• connectors – hubs, switches, cables• network OS – the program that “runs” the network

3.4.1-2


http://www.ib-computing.com/program/core/networks.html

WANWide Area Networks use public communication (telephone) to connect widely-separated nodes.The Internet is only one example – international corporations can create their own WANs without using the Internet, although this is less common.Some important issues for WAN’s are:• Compatibility – protocol, platforms• Speed – actually bandwidth

• Security – encryption, encoding, privacy• Reliability – error-rates, error-detection, error-prevention, error-recovery

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http://www.ib-computing.com/program/core/networks.html

http://www.ib-computing.com/program/core/networks2.html

PeoplePeople play a crucial role in computer systems.They have various roles and responsibilities:

• Producers (engineers, programmers)• Technicians (installation, support, repairs)• Professional Users (office workers, authors)• Personal Users (home, recreation, games)


Computer Systems Hardware - System Unit Software - Operating System Peripherals...

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