SCHEME OF WORK FOR 2ND TERM
|
WEEK |
TOPIC |
|
1 |
Review
of first term examination |
|
2-3 |
OUTPUT
DEVICES ·
Definition of
output devices ·
Examples of
output devices ·
Structure of
the CRT monitor ·
Types of
Printers ·
Differences
between Printer and monitor |
|
4-5 |
COMPUTER
SYSTEM SOFTWARE ·
Definition of
system software ·
Types of system
software ·
Definition and
functions of Operating system ·
GUI and CLI |
|
6 |
COMPUTER
APPLICATION SOFTWARE ·
Definition of
application software and types ·
Examples of
application packages |
|
7 |
PROGRAMMING
LANGUAGES ·
Definition of
Programming language ·
Levels of
programming language ·
Characteristics
of each level of programming language ·
Differences
among the levels of programming languages ·
Examples of
programming languages |
|
8-9 |
BASIC
PROGRAMMING LANGUAGE ·
BASIC character
set, operators data types, keyword, variable/constant, expressions,
statements ·
BASIC program
examples |
TOPIC ONE: OUTPUT DEVICES
Output
devices are devices that enable the computer to communicate the results of data
processing carried out by it to the user. These devices enable the computer to
display text, graphics (pictures and images) or produce sound. Examples of
output devices include monitor, printer, speaker, plotter, braille embosser
etc.
Features and uses of output devices
- Monitor: The monitor, also called Visual
Display Unit (VDU) is a TV-like structure attached to the System Unit through
the VGA cable. It displays text and graphics (images). The content showing on
the monitor is called a soft copy.
- Printer: A printer is a device attached to
the System Unit through the USB cable or other types of cable. It is used to
produce the information showing on the monitor on paper, transparencies, and
plastic. Such a printout is called a hardcopy.
- Speaker: A speaker is a device used for
producing sound captured by the microphone or music in mp3, wav, etc. formats.
Speakers come in different forms such as headphones, earphone (canal phones),
headset etc. and can also be used with portable devices such as mp3 player,
mobile phones etc.
- Plotter: A special type of printer used for printing drawings, charts, maps etc. using multi-coloured automated pens. It is usually used by architects, engineers and surveyors. Though they are rarely used now and are being replaced by wide-format conventional printers, which can produce high-quality graphics.
- Projector: A device that helps directs the content on a display screen (monitor) onto a particular flat surface.
- Braille Embosser: is a device that can generate the printed material using the braille writing system for blind or visually impaired users.
Structure
and type of CRT monitor
The Cathode Ray Tube (CRT) used as a computer monitor was
invented by Karl Ferdinand Braun. This monitor employs the CRT technology used most commonly in
the manufacturing of television screens. In this, a stream of intense high
energy electrons is used to form images on a fluorescent screen. A cathode ray
tube is basically a vacuum tube containing an electron gun at one end and a
fluorescent screen at another end. From this electron gun, a process called
thermionic emission generates a strong beam of electrons. These electrons
travel through a narrow path within the tube with high speed using various
electro-magnetic devices and finally strike the phosphor points present on the
fluorescent screen, thus creating an image. Today, CRT monitor are
being replaced with flat Plasma screen, Liquid Crystal Display (LCD) and Light
Emitting Diode (LED).
Types of monitor
There
are two types of monitor, namely:
1. Monochrome monitor:
This monitor displays its characters in only one colour. The colour could be
white, green or amber. Looking at the monochrome monitor, one can see two
colours; one colour for the background and one for the foreground. The two
colour combinations can therefore be black and white, green and black or amber
and black.
2. Colour monitor:
This monitor displays information in colours. It is similar to a colour
television but it handles data more quickly and has a sharper output.
Types of printer
There are two types of printer, namely impact and non-impact
printers.
I. IMPACT PRINTERS:
This type of printer behaves like a typewriter whereby a character is printed
when a metal slug strikes on a carbon ribbon. Impact printers have contact with
the surface of the paper. Examples of impact printer include the following:
A. DOT MATRIX printer:
This prints characters and graphic images by impacting a ribbon and
transferring dots of ink onto the paper. It prints dot matrix characters by
pressing the end of selected wires against ribbon and paper. The dots are used
to form the characters and images on the paper.
B. LINE printer:
This prints a line of character at a time. The output speed is between 200 to
3000 lines per minute (LPM)
C. CHARACTER printer:
This prints one character at a time moving across the paper. The output speed
range from 200 to 400 characters per second (cps)
II. NON-IMPACT PRINTER
Non-impact printer creates images
on paper in a manner similar to that of a photocopying machine. They do not
have contact with the surface of the paper. Examples include:
A.
INK JET printer: This prints by spraying small streams
of quick-drying ink onto the paper and using it to form characters, shapes and
images. The ink is stored in disposable ink cartridges, which can be black or
coloured. They are found in homes and offices.
B.
LASER printer: This uses an electrically charged drum
to transfer toner or dry ink onto paper like the photocopier does. It traces an
image by using a computer-controlled laser beam.
C.
THERMAL printer: This prints by transferring dots of
ink or dye from a ribbon onto paper and passing the ribbon and the paper across
a line of heating elements. The characters are produced with a print head
containing a matrix of small heating elements. This printer is very quiet in
operation because the printer head does not strike the paper.
DIFFERENCES
BETWEEN IMPACT AND NON-IMPACT PRINTER
|
IMPACT
PRINTER |
NON-IMPACT
PRINTER |
|
Makes noise while printing |
Does not make noise while printing |
|
Produces low quality images |
Produces high quality images |
|
Uses ribbon to print |
Uses ink (dry and wet) to print |
|
Does not have heating element |
Has heating element that dries the ink on paper |
|
Prints only one colour at a time |
Can print more than one colour at a time |
|
Has striking pins/heads that strike the characters or dots
on paper |
Does not have striking pin heads to strike characters on
paper |
DIFFERENCES
BETWEEN THE MONITOR AND THE PRINTER
|
MONITOR |
PRINTER |
|
Has screen |
Has no screen |
|
Uses no ribbon, ink, cartridge or toner |
Uses ribbon, cartridge,
ink or toner |
|
Uses no paper |
Uses paper and printable medium |
|
Display texts, images and pictures |
Prints text, images and pictures on paper |
|
Some have vacuum tubes or a liquid crystal |
Has no vacuum tube or a liquid crystal |
|
Has no paper tray |
Some have paper tray |
TOPIC
2: COMPUTER SYSTEM SOFTWARE
Definition of software
A computer software
(or software) is a general term used to describe a set of instructions usually
called a program, which control the operation of a computer or used to
accomplish a specific task.
Types of software
Software
can be broadly divided into two, namely:
i. System software:
This software helps direct and control the running of computer’s hardware and
other connected devices. It helps to manage computer resources such as memory
and processor. Examples include Operating system, Translators and utility
software.
ii. Application software:
This software enables the computer to perform specific tasks. Examples include
word processing package, spreadsheet package, game software etc.
Types of System software
1. Operating system:
Operating system is a
suite/set (collection) of programs/software that controls the execution of
application programs and coordinates/manages the hardware components. It can
also be defined as a set of programs that controls and manages computer
resources/components and provides other useful services. The purpose of an
operating system is to provide an environment in which a user can execute
programs in a convenient and efficient manner.
Functions of Operating system
i.
Serves
as an interface between the user and the computer/hardware and software
ii.
Access control/ System Security: By means of password
and other similar access control techniques the OS prevents unauthorized access
to programs and data.
iii.
Controls program execution: The OS runs and control all other
system programs and application software
iv.
Booting/Starting up the computer: The operating system manages the
starting up of the computer
v.
Controls
hardware resources
vi.
File-system manipulation (for users
and their programs)
- read and write files and directories, create and delete them, search them,
list file Information, permission management.
vii.
Control
over system performance:
The OS records the delay between the request for a service and the
response from the system and manages the situation accordingly.
viii.
Protects
the system from errors and failures/error
handling
ix.
Task management: The OS gives control to the program
the user brings to the foreground (from among multiple opened programs).
x.
Device management: The device management function
controls hardware devices by using special software called device drivers,
which are installed in the operating system. This makes the operating system
recognize the device.
xi.
Memory
management
Examples
of Operating system
Operating system can be grouped
into two, namely, the Graphical User Interface (GUI) and the Command Line Interface
(CLI).
·
The GUI group makes use of windows, icons, mouse, scroll bar, and
Pointer. In this group, we have the Microsoft series (Windows 95, 98, NT/2000,
ME, XP, Vista, 7, 8,10), Chrome OS, Apple System 7 and macOS, Linux variants
like Ubuntu.
·
The CLI group includes the IBM Disk Operating system (DOS) that is
phased out, the Microsoft Disk Operation System (MS-DOS) and UNIX. The Command
line is a text-based interface that allows the user to interact with the
computer system by typing in commands (instructions).
2. Translators: Translators are
programs that convert programs written in languages other than the machine
language to machine language. Examples are Assembler, Interpreter and compiler.
3. Utility Software: Utility software is
system software designed to help analyze, configure, optimize or maintain the operation
of a computer, its devices, or its software. Examples include disk utilities
like defragmenters, compressors and cleaner. There are also other operating
system utilities such as antivirus programs, registry cleaners, Screen saver,
file viewer (windows explorer), editors and system restoration programs. Utility
softwares are built into the computer operating system, however may be
installed separately.
TOPIC 3: COMPUTER APPLICATION SOFTWARE
Application softwares are
the programs that enable computer to perform specific productive task.
Types of application software
1. User application development program:
This kind of software is used to develop programs usually called in-house
programs, which are customized to perform specific functions for the user such
as administration, payroll, production control, banking, inventory etc. Examples
include NetBeans, Eclipse, Android studio etc.
2. Application packages: The
application packages are software packages that perform generalized functions
and are produced for the general public to use. This category of software can
be grouped based on their functions as listed below:
- Database management: Examples include Microsoft
Access, Oracle, MySQL, Dbase etc. which are used for creating, maintaining and updating
databases (collection of related information).
- Word processing: Examples include
Microsoft Word, Lotus WordPro, Corel WordPerfect, Professional Write etc. are
used to create document such as letter, memos made up of textual and graphical information.
- Spreadsheet, calculation and data
analysis: Examples include Microsoft Excel, Amipro, Quattro Pro, Lotus 1-2-3
etc. which contains grids of cells arranged in rows and columns used for entering
data for calculation and analysis.
- Graphic designing: Examples include
Corel Draw, Adobe Photoshop, Paint etc. which can be used to draw and make
designs related to graphics.
- Slide presentation: Examples include
Microsoft PowerPoint, Impress, Prezi etc. which contains collection of slides
used to hold information that can be presented in form of slide show.
- Email management: Examples include
Microsoft Outlook, MS Exchange etc. which contains tools for sending and
receiving electronic mail (e-mail).
TOPIC 4: PROGRAMMING LANGUAGES
Computer programming is the specification of instructions
that a computer follows to perform a particular task.
A computer program is a sequence of instructions that tells
a computer what to do and how to do it.
A programming language is a language used to write
instructions for the computer. Programming language, like any human language
has rules and grammar that governs the formation of a statement.
The syntax of a
language describes the possible combinations of symbols that form a correct
statement. The meaning given to these combinations of symbols is called
semantics.
Levels of programming
- Machine
language: Is a system of instructions and data directly understood by
the computer’s CPU. These instructions and data are combinations of sequence of
bits (0’s and 1’s) with different patterns corresponding to different commands
to the machine.
- ii)
Assembly
language: This language uses abbreviations or symbolic letter codes (mnemonics) to write each
machine-language instruction. The letter codes are used in place of binary
digits. Programs written in Assembly language are translated into machine
language by an Assembler.
- iii)
High
level language: The instructions of this language are
written using words that are very close to human languages and algebra-type
expression. They are closer to human understanding and are translated into
machine language by a compiler or an interpreter.
Both machine
and assembly languages are also called low level languages.
Features/characteristics
of each level of programming language
i)
Machine
language
1. These
instructions consist of binary numbers (set of 0’s and 1’s)
2. This
language is machine dependent i.e. instructions written for a particular type
of computer can only be executed on that particular machine.
3. It
is very hard for people to write and understand thus making the programs error
prone.
4. Each
CPU design has its own machine language, which is the set of instructions that
the CPU of that machine understands and executes.
ii)
Assembly
language
1. Uses
mnemonics (symbolic operation codes) and operands (symbolic storage address).
2. Machine
dependent
3. For
any assembly language instruction, one machine language instruction is generated.
4. It
illustrates fundamentals of computer construction and operation.
iii)
High
level languages
1. Machine
independent: programs written or compiled on one type of Computer can be
executed (run) on different type of computer that has different architecture.
2. It
uses instructions that seem English-like and thus closer to human
understanding.
3. Easy
to detect errors
4. Consists
of well-defined syntax and standard.
5. Requires
a compiler to translate into machine language before the computer can execute
them.
6. Programs
written in HLL are called source code and the compiled version is called object
code.
Comparison of levels of Programming Languages
|
MACHINE
LANGUAGE |
ASSEMBLY
LANGUAGE |
HIGH LEVEL
LANGUAGE |
|
Difficult to learn, write and debug |
It is difficult but easier than machine language |
It is easier to learn, write and debug |
|
It is machine dependent |
Machine dependent |
Machine independent |
|
Does not require a translator |
Requires a translator called Assembler |
Requires a translator called a compiler or interpreter |
|
Instructions
consist of binary digits (1’s and 0’s) |
Instructions
consist of symbols and mnemonics |
Instructions
consist of English-like words, symbols and numeric. |
Examples of Programming Language
The
following are some of the many programming languages:
Python,
Ada, Algol, APL, BASIC, C, C++, C#, COBOL, FORTRAN, Java, JavaScript, LISP,
Pascal, PHP, Perl, Python, Visual Basic etc
TOPIC 5: BASIC PROGRAMMING
LANGUAGE
The
BASIC programming language was developed in 1964 by John G. Kemeny and Thomas
Kurtz at Dartmouth College. BASIC is an acronym that stands for “Beginner’s
All-Purpose Symbolic Instruction Code”
Basic Character Set
A
character set is simply a list of letters, numbers and symbols that provide one
with the characters used in a particular language. BASIC as a language has its
own character set, they include the following:
·
Alphabets characters (A to Z or a to z)
·
Numeric character (0, 1 to 9) including hexadecimal
characters.
·
Special characters that perform special functions in BASIC
Arithmetic operators
|
CHARACTER |
NAME |
USES |
|
* |
Asterisk |
For
multiplication, e.g. A*B or (3*5) |
|
- |
Minus
|
For
subtraction, e.g. M-N or (4-1) |
|
+ |
Plus |
For
addition, e.g. K+N or (1+6) |
|
/ |
Forward
slash |
For
real division, e.g. A/B or (7/3)=2.33 |
|
\ |
Bask
slash |
For
integer division, e.g. P\G or (7\3)=2 |
|
^ |
Caret
|
For
exponentiation, e.g. A^B or (7^3) |
Relational (Comparison) Operator
|
CHARACTER
|
NAME |
USES |
|
= |
Equal
to |
A=B |
|
> |
Greater
than |
A>B |
|
< |
Less
than |
A<B |
|
>
= |
Greater
than or Equal to |
A
>=B |
|
<
= |
Less
than or Equal to |
A
<= B |
Data types
Data
type is a description of the set of values and the basic set of operation that
can be applied to values of the type.
i)
Integers:
a positive or negative number without decimal. It has a range of values from
-32,768 to 32,767. Each value is stored using 2 bytes of memory (storage)
space.
ii)
Real
numbers: numbers with fractional parts or with a decimal point. It
is stored using 4 bytes of memory space.
iii)
Boolean:
consist of only two values; “YES and NO” or “True or False” or 1 or 0.
iv)
String:
a sequence of characters in double quote. For example, “Computer Studies” is a
string value with 16 characters. Each character is stored using 8 bits (one
byte) in the ASCII character set and two byte in the UNICODE character set.
Alphabet is represented in ASCII.
Keyword
Keywords
are words that have special meaning and function in BASIC. Such words must be
used strictly according to their functions, otherwise the computer will respond
with error message.
Here are some of the
BASIC keywords and their uses
|
KEYWORDS |
USES |
EXAMPLE |
|
REM |
Make
comment about an instruction or about the whole program |
10
REM Program to add two numbers |
|
INPUT |
Used
to ask the user to supply the data to be processed while the program is
executing |
5
INPUT A,B,C |
|
PRINT |
Used
to display the output of operation on the screen |
PRINT
“The values”, A,B |
|
LET |
Used
to assign a value to a variable |
3
LET A=5 |
|
READ |
Used
to tell the computer that the data to be processed is supplied within the
program statements. Used together with DATA keyword |
10
READ A,B |
|
DATA |
Used
to show the computer the data it is asked to read in the READ statement. Used
along with READ keyword. |
10
DATA 4,7 |
|
END |
To
end the program |
5
END |
Variables and Constant
Variable is an
identifier or a name of a memory location where data (values) can be placed or
stored. Because the value placed in a memory location can be changed at any
time, we call such memory location “a variable”.
However, when the value of a memory location is not to be changed, we refer to
such memory location as “constant”.
Declaration of Variables and
Constants
When
you are to supply data to the computer for processing, you are required to
state the data type. This help the computer to interpret it and an appropriate
storage space is reserved for the data. To achieve this, the keyword DIMENSION
(or DIM) is used to specify the data type. For example, variable Name and Pie
are to hold “character and real”
data values respectively. This can be written in BASIC as follows:
1. DIM
Char Name, INT Age, REAL Height
2. DIM
Name AS Char, Age AS INT, Height AS Real
3. DIM
Name$, Age%, Height!
Rules for naming Variable
1. Every
variable must begin with an English alphabet (A to Z or a to z).
2. The
name must not be more than 40 characters in length.
3. Names
can be alphanumeric (combinations of alphabet and numbers).
4. Name
must not be any keyword
5. Do
not include a blank space in the name.
Basic Expression
A
BASIC expression is formed when two or more character, strings, variables or
constant are combined with arithmetic, relational or logical operators
Examples
include:
1. F2
+ 7 (add 7 to the value in the variable F2)
2. A+
B (add the value in A to the value in B)
Arithmetic
operation precedence
The rule that guides
the order in which operation must be performed in an expression is known as
“precedence” rule.
|
THE ORDER |
SYMBOL |
NAME OF SCHOOL |
|
1 |
(
) |
Bracket |
|
2 |
^ |
Exponentiation |
|
3 |
- |
Negation |
|
4 |
*or
/ |
Multiplication |
|
5 |
\ |
Integer |
|
6 |
MOD |
Modulo
(remainder) |
|
7 |
+
or - |
Addition
or subtraction |
BASIC statements
A BASIC statement is any valid instruction given to the
computer for processing of data. BASIC statement may be an expression, an
assignment, a reserved word (keyword) with or without arguments or their
logical combinations
1.
Declaration
statement: Every variable in a program must be declared before it can
be used. A variable must be declared with appropriate data type. Example of
declaration statements are:
DIM
Age AS Integer
DIM
Name AS Character
2.
Assignment
statement: This statement causes a computer to store a value in a
variable. The statement has two sides separated by the equality sign (=).
Name
= “Computer Studies”
Age
= 16
3.
Input
statement: This statement is used to ask the user to supply the data
to be processed while the program is executing.
INPUT
Name$, Age% (This statement is not
interactive)
INPUT
“Enter the Name and Age”, Name, Age (This
statement is interactive)
4.
READ
and DATA statement: The READ statement is used to supply
data into the program, but unlike the INPUT statement, the programmer supplies
the data inside the program codes using the DATA keyword.
READ
“Enter Name and Age”, Name$, Age%
DATA
“Obasa Mustapha”, 20
5.
PRINT statement: This statement is used
to show the result of data processed.
QBASIC
program examples
1 REM This program calculates the area of any
rectangle and print the length, width, and area.
2 ‘To calculate the Area of a Rectangle we must
know its length and width"
3 Length = 10
5 Area = length * breadth
6 PRINT “Area is “, Area
7 END
10 REM program
to solve a quadratic equation
20 INPUT “Enter
coefficients a, b, c “; a,b,c
30 Discrim =
b^2 – 4*a*c
40 If Discrim
> 0 then
50 Dummy =
sqr(Discrim)
60 PRINT “There
are 2 distinct roots”
70 PRINT “first
root (X1) = “; (-b + dummy)/(2*a)
80 PRINT
“Second root (X2) = ”; (-b –dummy)/ (2*a)
90 ELSEIF
Discrim = 0 THEN
91 PRINT “There
is only 1 root, the 2 roots coincide”
93 ELSE
94 PRINT “The roots are imaginary”
95 Dummy = sqr
(- discrim)
96 PRINT “Real
part = “; - b /(2*a)
97 PRINT
“Imaginary part = ”; dummy/(2*a)
98 END IF
99 END
