Computer Based Systems

Stage 2 Information Technology Studies

Computer & Communication Systems

General System ConceptsDefinitions

• System

• Synergism

• Boundary

• Environment

• Interface

• Feedback

Input Processing Output

Interface

Feedback

Systems Functions

• Input

• Processing

• Storage

• Output

• Control

Inpute.g. keyboard

ProcessingCentral Processing

Unit (CPU)

Outpute.g. printer

Control

Secondary Storagee.g. fixed disk,

flash drive

Systems ComponentsHardware

• Input devices• Output devices

• Auxiliary storage

Personnel• Users

• Operators

Software• System software• Utility software

• Application software

Processes• CPU architecture

• Fetch-execute cycle

Data• Files

• Database

Hardware

• Central Processing Unit

• Input Devices

• Output Devices

• Secondary Storage

Central Processing Unit

• Integrated Circuit (IC)

• Central Processing Unit (CPU)

• Microprocessor

• Buses

• Control Unit

• Arithmetic/Logic Unit (ALU)

• Registers

Types of Register

• Storage register

• Address register

• Accumulator register

• Instruction register

• Program counter register

• General purpose register

Central Processing Unit(continued)

• Word length• Primary Storage

– Random Access Memory (RAM)• Dynamic RAM (DRAM)• Static RAM (SRAM)• Non Volatile RAM (NVRAM)

– Read Only Memory (ROM)• Programmable ROM (PROM)• Erasable Programmable ROM (EPROM)

• Address• Machine Language

Input Devices

• Keyboard

• Mouse/Trackball

• Graphics Tablet

• Barcode scanner

Input Devices(continued)

• Microphone

• Camera/Scanner

• Joystick/Joypad

• 3D Scanner

Output Devices

• Temporary – “Soft Copy”

• Permanent – “Hard Copy”

Output Devices

• Temporary– Monitor– Speaker

Output Devices

• Permanent– Printers– Plotters– CNC Machinery

Secondary Storage• Magnetic storage

– Magnetic Disks– Magnetic Tape

• Optical storage– CD– DVD

• Other storage• Sequential and Direct Access

Storage

Software Application Programs

Utility Programs

System Software

Hardware

Operating System Services• Process Management• Memory Management

– Allocating Memory– Virtual Memory– Memory Protection

• Disk and File Systems– Management of Files– Different File Systems

• Journaled• Larger file/device sizes• Case (in)sensitivity• Pooling of Disk Space

• Networking

Operating System Services

• Security– Internal security– External security

• Graphical User Interfaces– Versus Command Line Interfaces– Recognition v. Recall

• Device drivers