QBasic

Chapter 1 – Introduction to Computer Systems & QBasic

Introduction

Importance of computers What is a computer? Computer Programs Programming Languages

What Computers Can Do

Arithmetic Operations Comparison (logical) operations Storage & retrieval operations

Speed & Accuracy

Components of a Computer System

Hardware– System Unit– CPU – control unit & arithmetic logic unit– Main Memory

Peripheral Devices– Input– Output

Components of a Computer System

Secondary Storage– Floppy disk, hard drive, CD, DVD, Flash Drive

Secondary Storage Devices– Used to copy data to & from secondary storage

Storage space measured in Bytes– Kilobyte, Megabyte, Gigabyte, Terabyte

Categories of Computer Systems

Supercomputers Mainframes Minicomputers Microcomputers

Where Did All this Start?

Operating System User Interface

– Command-Line Interface– Graphical User Interface

DOS – Disk Operating System– Command-line– Used to run QBasic

QBasic

Designed from the BASIC language Enhanced, menu-driven Online Help Structured language

Running QBasic

Installed on your H: drive Double click on QB.exe Use mouse and arrow keys to navigate Menu Bar

– File - Edit– View - Search– Run - Debug– Options - Help

QBasic

Title Bar Reference Bar Immediate Window

Menus

File– New– Open– Save– Save As– Print– Exit

Menus

View– SUBs– Split– Output Screen

Run– Start– Restart– Continue

Entering & Editing Programs

Use CLS to clear screen at beginning Type commands one line at a time Hit Enter to go to next line Scroll up & down as needed

Key Words in QBasic

CLS INPUT PRINT

– Put text in “double quotes”– Use semi-colon ; between quoted text & variable

names Use $ for text variables

– User$, Instructor$, Title$

Being a Responsible Computer User

Computer Ethics Hardware

– Backup data– Store media properly

Software– Commercial Software– Shareware– Public-domain Software