The document discusses computers and programming basics. It covers computer hardware components like the system unit, CPU, memory and peripheral devices. It also discusses software topics like operating systems, programming languages, and QBasic. QBasic is an introductory programming language that uses basic commands like PRINT, CLS, INPUT and arithmetic expressions. The document provides examples of using these commands and expressions in simple QBasic programs.
4. Hardware
System Unit
CPU – control unit & arithmetic logic unit
Main Memory
Peripheral Devices
Input
Output
5. 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
7. Operating System
User Interface
Command-Line Interface
Graphical User Interface
DOS – Disk Operating System
Command-line
Used to run QBasic
8. Designed from the BASIC language
Enhanced, menu-driven
Online Help
Structured language
9. 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
15. 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
16. CLS
INPUT
PRINT
Put text in “double quotes”
Use semi-colon ; between quoted text & variable names
Use $ for text variables
User$, Instructor$, Title$
17. Computer Ethics
Hardware
Backup data
Store media properly
Software
Commercial Software
Shareware
Public-domain Software
18. There are also special functions called
“commands” (also called “instructions”). A
“command” tells that the Qbasic interpreter to do
something.
The PRINT command tells the Qbasic interpreter to
print something to the screen. In this case, the
interpreter printed “Hello World ! “.
TIP: Instead of typing PRINT, you
can enter a question mark. For
example:
?”Hello World!”
19. With the PRINT command, you can also print numbers
to the screen. Delete the current program (unless you
already have) and write the following:
PRINT 512 (or ?512)
<press Enter>
Press F5 to run the program, the program outputs:
512
20. An expression is something the interpreter
calculates (or evaluates). Such us:
1 + 1 (returns 2)
100 – 47 (returns 53)
3 * 34 (returns 102)
80 / 4 (returns 20)
(100 * 3) + (returns 356)
21. CLS
- An abbreviation that stands for the words Clear Screen .
In the above program, when you used CLS on line 60, all
the words that were printed to the screen were wiped
away.
PRINT
- Writes the screen. There are commands to other things
like printer, but that’s to be discussed later. Each new
Print command will start printing on a new line. To
insert a blank line, don’t specify a string to print. The
syntax for “PRINT” is PRINT “[whatever you want to be
here]”
22. END
- It stops the program at that line; that is, anything
that’s added after that won’t show. That’s why the
PRINT command on line 90 didn’t print anything. The
END command can be included in control structures
to end the program if a condition is met. This will be
discussed with control structures.
Given the state of computer speed today you
should not see the paragraph displayed by lines 20
through 50, it should be cleared by the CLS statement
on Line 60 before you have a chance to see it.
23. An operator is a code element that performs an
operation on one or more code elements that hold
values. Value elements include variables, constants,
literals, properties, returns from function and operator
procedures and expressions.
An expression is a series of value elements
combined with operators which yields a new value. The
operators act on the value elements by performing
calculations, comparisons or other operations.
24. Visual Basic provides the following types of operators:
Arithmetic Operators perform familiar calculations on
numeric values, including shifting their bit patterns.
Comparison Operators Compare two expressions and
return a boolean value representing the result of the
comparison.
Concatenation operators join multiple strings into
single string.
Logical and Bitwise Operators in Visual Basic combine
Boolean or numeric values and return a result of the
same data type as the values.
