CSCI 1200 / ASSC 1000

Jbenoit@cs.dal.ca

Software

• program : instructions for hardware.

• makes computers useful.

• early computers : re-wiring.

• today : programming languages.

Fast & Stupid

• very basic instructions :• math, logic, move & copy values, etc…

• results achieved through speed.

• computers are unforgiving, instructions must be precise.

Programming

• algorithm – general procedure

• programming – handle the specifics

• debugging – finding and fixes errors.

Languages

• Machine Language

• Assembly Language

• High Level Programming Language

• Natural Language

Machine Language

• understood by the hardware.

• executed by the CPU.

• binary strings.

• instruction set.

Assembly Language

• mnemonics mapped to bit strings.

• slow & error-prone for people.

• better hardware performance.

00000100 10000000

00000000 10000001

00000101 10000000

00001111 00000000

LOAD 128

ADD 129

STORE 128

HALT

High Level Language

• more familiar for people.

• english-like structure.

• examples : C, C++, Java, FORTRAN, and Visual Basic.

High Level Language

var x;

var y;

if (x == 2) then

x = y + 1;

else

x = 0;

print(“the value of x is ”, x);

Translation

• Compiler / Interpreter

• source code to machine code.

• high level language is hardware independent, but translated to hardware dependant machine code.

Kinds of Software

• Translation Software

• System Software :• Operating systems (Wiindows, UNIX,etc) • “talk” to the hardware

• Application Software :• use operating system and hardware to do

something, MS Word, netscape etc.

System Software

Operating System : • communication with peripherals• coordination• storing and retrieving data • running programs • managing memory• network communications• resource monitoring, account, security

System Software

Operating System Details :

• Windows XP, Mac OS X, UNIX, Linux, Window CE

• platform : OS and hardware (Wintel).

• emulation : like something else.

System Software

Utility Programs :

• repairing damaged files.

• copy files from one storage device to another.

• guarding against viruses.

• may look like are of the OS.

System Software

Device Drivers :

• control and interface a hardware component or peripheral.

• may come with the operating system, or with the component.

Input Devices

Keyboards :

• Qwerty / Dvorak / Alphabetic

• ergonomic

• compact

• membrane

• one handed

• folding

Input Devices

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Input Devices

Pointing Device :

• selecting from options / menus.

• spatial tasks / graphics applications.

• efficiency

Input Devices : Pointing

• Mouse : mechanical, light

• Touch Pad : finger pressure

• Track Ball : upside down mouse

• Pointing Stick : TrackPoint, Isopoint

• Joystick : and other gaming devices

• Tablet & Stylus

• Touch Screen

Input Devices : Reading

• Optical Mark Readers

• Bar Code Readers

• Magnetic Ink Character Readers

• RFID Tags & Readers

Input Devices : Reading

• Optical Character Recognition

• Handwriting recognition

• Smart Whiteboard

Input Devices : Digitizing

• Scanner

• Digital Camera

• Video Digitizer

• Digital Video Camera

Output : Monitor

• most familiar (VDT)

• diagonally in inches

• pixels, dpi, resolution

• colour depth : number of colours that can be displayed at one time

• video adaptor / video card

• VRAM

Output : Monitor

• Liquid Crystal Display

• Cathode Ray Tube

Output : Printers

• impact & non-impact

• dot matrix printers & line printers

• laser & ink jet

• resolution

• plotter

• multi-function devices..