SYMBOLIC REPRESENTATIONS/CODING SCHEMES
In computing, a single xter e.g. a letter or symbol is represented by a group of bits.
Various codes have been developed to represent data in a computer and to enable it to easily
transmit data between systems. Data

DATA REPRESENTATION IN A COMPUTER
Data: Raw facts and figures that a computer processes by following a set of instructions called
programs. The way in which data is stored and represented depends on the medium storing it and the
type of data.
Types of dat

DATA SECURITY THREATS AND CONTROL MEASURES
Information within the organization is the power of the organization and therefore the
information stored within the organization needs to be protected in order to maintain the integrity
of the organization.
The

Using Twos complement
It is achieved by getting ones complement of a number and then 1 is added. E.g
Find the twos complement of 4510
Solution
2 45
2 22
1
2 11
0
2 5
1
2 2
1
2 1
0
0
1
=1011012
In 8 bits =001011012
The ones complement =110100102
Adding 1 t

2. DATA INPUT
Is the act of entering the collected data and instructions in a computer using
an input device.
The input data is converted from human readable form to machine readable
form (binary form).
3. DATA PROCESSING
Is the transformation of the inpu

DATA PROCESSING METHODS
These are different ways in which an organization may decide to convert
(process) data collected over time to information.
Data can be processed :
Manually
Mechanically
Electronically
1. Manual Data Processing
It involves the use o

BINARY SUBTRATIONS
a) Direct Subtraction
02-02=02
12-02=12
12-12=02
02-12=12 borrow 1
102-12=12
For Example
111012-011102=011112
b) Ones Complement
For Example 510-310
i) Rewrite the problem as 5+(-3) to show that the computer performs binary subtractions

TYPES OF DATA REPRESENTATION
1. NUMBER SYSTEMS
There are 4 main categories of number systems:
a) Decimal number system
b) Binary number systems
c) Octal number systems
d) Hexadecimal number systems
a) DECIMAL NUMBER SYSTEMS
Is a number system that has ten

CONCEPTS OF DATA REPRESENTATION IN DIGITAL COMPUTERS
Data and instructions cannot be entered and processed directly into computers using human
language.
Any type of data must first be converted into machine readable form i.e. binary form.
A computer toget

DATA INTEGRITY
Is the accuracy, validity and completeness of data entered in a computer or
received from an information system.
Integrity of data is a major consideration when deciding a method of data
processing.
Integrity is measured/ assessed in the fo

PRESENTING SIGNED BINARY NUMBERS (POSTIVE AND NEGATIVE) IN A
COMPUTER
There are 3 ways of presenting signed numbers in a computer:
Prefixing an extra sign bit to a binary number.
Using ones complement
Using twos complement
)
Prefixing an extra sign bit

DECIMAL FRACTION TO BINARY
1. Multiply the fraction part by 2 and note down the product.
2. Take the fraction part of the immediate product and multiply it by 2 again.
3. Continue multiplying the fractional part by 2 until the subsequent product is 0 or s

TYPES OF COMPUTER PROCESSING FILES
There are several types of files used for storing data needed for
processing, reference or backup. These include:
Master file
Transaction file
Reference file
Backup file
Report file
Sort file
Master file
Is the main file

Data Backup Equipment
There are many choices you can make about the equipment you use to back up
your valuable data. Your decision will depend on factors such as the amount of
data that needs to be backed up, the value of the data, how much you can afford

Computer errors and accidental access
Data damage or loss is often caused by people who shouldn't have been let loose in
the first place. Whether you lose data through deliberate nastiness or complete lack
of knowledge, the result is the same.
Control mea

BACKUP MEDIA
QIC Quarter Inch Cassette - almost universally used for backing up file servers.
They have very high media quality and very large capacity (e.g. 40 to 80
gigabytes)
CD-R, DVD-R - one-time optical recording of data. Once written, it cannot be

Data Disaster Recovery Plan
Thanks to Jane W for suggesting this page
Read an excellent Age article explaining the need for tested backups when
everything goes wrong
You are the IT manager at work.
Late one night, you get a phone call.
You race to work, a

Hexadecimal to Binary
Here, each digit is represented by 4 binary digits.
A simple relationship exists between hexadecimal and binary because base 16 is 24 of 2.
The maximum hexadecimal digit i.e. F (15) can be represented with a maximum of 4
binary digit

Multi-programming/ tasking
More than one program (task) are executed apparently at the same time by a
single processor (CPU).
The OS allocates each task a time-slice and decides the order in which they
will be executed. This scheduling is done so fast tha

CONVERSION OF NUMBERS FROM ONE SYSTEM TO ANOTHER
1. A) BINARY TO DECIMAL
i) Write the place value starting from right hand side.
ii) write each digit under its place value
iii) Multiply each digit by its corresponding place value.
iv) Sum up the products.

Hexadecimal to Octal
In this case, convert the hexadecimal number into binary equivalent and then convert the binary to
octal i.e.
Hexadecimal
Binary
Octal
Example:
a) Convert BC216 to octal equivalent:
Solution
Convert BC216 to binary equivalent i.e.
hex

B) DECIMAL TO BINARY
To convert a number from base 10 to base 2, the number in base ten is repeatedly divided by
two until the dividend is zero.
On each division the remainder is noted.
Remainders which are either 0 or 1 are written to the right of the qu

DATA COLLECTION (Gathering/ Fact finding)
It involves looking for or getting data from its point of origin to the computer
for processing.
The methods involved for data collection include:
Interviews
Questionnaires
Observations
Sampling: Select repres

DATA PROCESSING
Definition of terms:
Data: Raw facts that do not have much meaning to the user. These include:
Figures, letters, symbols, xters etc.
Data cannot be used in decision making.
Information: Processed data that is meaningful to the user. Since

CONVERTING OCTAL NUMBERS TO BINARY AND VICEVERSA
Here, each octal digit is represented by 3 binary digits.
A simple relationship exists between octal and binary because, 8 is the cube of 2.
The maximum octal digit i.e. 7 can be represented with a maximum

5/7/15%
Data Mining Cycle
FINAL STUDY GUIDE
A brief description of what you should know
so far
Business Understanding
Supervised vs. Unsupervised
Formulating a target variable
Fill in the blank: I am trying to predict _
What is the difference between t

3/10/15
Data Mining Cycle
STUDY GUIDE
A brief description of what you should know
so far
Basic Terminology
Business Understanding
Instance/example
Formulating a target variable
Fill in the blank: I am trying to predict _
Features/attributes
Target

The boy and the puppy
Once upon a time, a Little kid that wants to buy a dog for play with him. One day he passed by the
pet stores and saw an advertisement that say Puppy in sales .When he saw the ad, he was exited
and decided to enter to the shop. The s

9
Chapter 9:
Moving to Design
9
Understanding the Elements of Design
Design is process of describing, organizing, and
structuring system components at architectural
design level and detailed design level
Focused on construction
Like developing blueprints

9
Chapter 9:
Moving to Design
9
Understanding the Elements of Design
Design is process of describing, organizing, and
structuring system components at architectural
design level and detailed design level
Focused on construction
Like developing blueprints