Extended Binary Coded Decimal Interchange Code (EBCDIC)
Is an 8-bit code scheme used to represent up to 256 xters. i.e. 2 8=256.
EBCDIC is mainly used in large IBM computers. E.g. A in EBCDIC is repre
BINARY ARITHMETIC OPERATIONS
In computing, Mathematical operations are performed in ALU. However, the ALU cannot perform the
binary subtractions directly. It performs it using complementation method.
QUESTIONS.
1) Differentiate between analogue data and digital data.
Analogue data_ a type of data that is continuous in nature.
Digital data - Data in discrete form.
2) Define the following terms
a) A
Distributed processing
It involves dividing a processing task to two or more computers that are
located on physically separate sites but connected by a data transmission
media.
Computers, software and
Extended Binary Coded Decimal (EBCD)
Is 6-bit coding scheme formed by adding a farther 2-bits in order to represent non-numeric xters.
This allows 64 xters to be represented. (26=64)
In the 6-bit codi
BINARY NUMBER SYSTEM
A number system that consist of two digits i.e. 0s and 1s to represent data in a computer. These
numbers are written to the base of 2.
This number system is similar to decimal in
ELECTRONIC DATA PROCESSING MODES
Data processing modes describe the ways in which a computer under the
influence of instructions by the operating system handle data during data
processing. These modes
CONVERTING HEXADECIMAL NUMBERS TO DECIMAL, BINARY AND OCTAL
a) Hexadecimal to Decimal
i) Write the place value starting from the right hand side.
ii) Write each digit under its place value. If a digit
DECIMAL TO OCTAL
To convert from base 10 (denary) to octal (base8), the number in base 10 is repeatedly
divided by 8 until the dividend is zero.
On each division the remainder is noted.
Example
Conver
American Standard Coded Decimal for Information Interchange (ASCII)
Is a 7-bit code scheme used to represent up to 128 xters. i.e. 2 7=128.
Since computers can only understand numbers, all xters must
FILE ORGANIZATION METHODS
File Organization: Refers to the arrangements of records or how data is stored in a file. File
organization is important as it determines the method of access, efficiency, fl
COMPUTER FILES
When discussing about operating system, we defined a file as an
organized collection of related information stored in a given storage
location and given a unique name for easier recall
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 maximu
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
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
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 dat
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 m
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)
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)
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
Electro
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
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 bi
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 or
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 t
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 compleme
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 frac
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
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 whi
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 equivalen
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