Introduction to Information and Information Systems
ICT Skills Book
Session 02 – Introduction to Computers
§ 2.1 – What is a computer?
A computer is an electronic device that manipulates information or “data”. It has the ability to store, retrieve
and process data. You can use a computer to type documents, send email and browse the internet. You can also
use it to handle spreadsheets, accounting, database management, presentations, games and more.
- It is a man-made machine
- It accepts instructions of a human given in a sequential manner
- As per the given instructions, it performs some calculations and does changes for the information fed
by human
- Releases or produces an output that is useful to the user
Hardware = physical structure with several parts like the monitor, processor, mouse and keyboard which are
tangible. Software = sets of instructions which are also called computer programs installed in the computer.
These softwares tell the hardware what to do and how to do to accomplish some tasks expected by the user to
get done by the computer.
§ 2.2 – Characteristics of a Computer
1. Speed: can perform tasks very fast.
2. Reliability: electronic components are dependable because they have a low failure rate.
3. Accuracy: is consistently high. Errors can occur but these are mainly due to human mistakes. If
inaccurate data is entered, the resulting outputs will also be incorrect (Garbage In, Garbage Out)
4. Diligence: a computer is free of boredom, tiredness, lack of concentration, etc. A computer can work
for hours without making any errors or complaints.
5. Versatility: the computer has the capacity to perform completely different types of work.
6. Power of remembering: everything a user stores can be retained as long as it is needed and can be
recalled when necessary.
7. No feeling: computers do not have emotions.
8. No IQ: computers cannot do any work without instruction from the user.
9. Storage: in-built memory primary storage. Has a limited capacity but is important as the processing
unit of the computer can act directly on instructions and data on the primary storage. Secondary
storage: storage devices which can be kept outside the computer.
§ 2.3 – Limitations of a Computer
- It can only do what you tell it to do.
- It cannot generate information on its own.
- It will give wrong information if you feed it with wrong data.
- It cannot correct wrong instruction.
§ 2.4 – Different Types of Computers
- Microcomputers: small in size, also called personal computers (PC)
- Minicomputers: used by multi-users. Used in laboratories.
- Mainframes: largest in size. Capable of handling and processing very large amount or data quickly.
- Super computers: used for performing complex data. Called workstations.
§ 2.5 – Different Types of Personal Computers (PCs)
A PC is designed as a more user-friendly device to be directly used by the end-user rather having an especially
skilled separate computer operator. PCs come in different forms:
- Desktop PCs: placed in a fixed location (desk). Monitor, mouse, keyboard are parts.
- Laptop: designed for mobile use. In-built keyboard, screen and touch pad.
- Netbook: smaller laptop.
- PDAs: Personal Digital Assistant. Handheld computers.
- Wearable computer: can be worn on the body.
, - Tablet: mobile computer. Touch screen, no formal key board.
§ 2.6 – Main parts of a computer system
- Hardware: tangible parts that make the computer. Physical parts.
- Software: set of instructions that tells computer hardware what to do. (computer program)
- Data: any fact or piece of information in a form suitable for use with a computer.
- User/Live ware: people are an essential part of a computer
Computer
system (design, build, repair) Hardware
Session 03 – Computer Hardware Processing Memory Input/Output Storage
§ 3.1 – What is Computer Hardware? devices devices devices devices
The physical equipments that are involved in the function of
the computer are called its hardware.
§ 3.2 – Processing Devices
The Central Processing Unit (CPU): an electronic device which
runs computer programs. It’s the brain of the computer, also
called the computer processor. There are two components:
- Control unit (CU): the CPU uses its CU to execute
instructions to process data. It also directs and
coordinates most of the operations of the computer.
The speed is measured in megahertz (MHz).
- Arithmetic and Logic Unit (ALU): performs arithmetic
(+, -, *, /), comparison (<, >, =) and logical (AND, OR,
NOT) operations.
§ 3.3 – Memory Devices
- Computer memory: a character is stored as a group of 0s and 1s (Byte). The 8 Bits 1 Byte
size of the memory is measured by the number of bites available. 1024 Bytes 1 Kilobyte (1KB)
While performing a processing operation there is a place needed to temporarily store 1024 KB 1 Megabyte (1MB)
instructions and data to use with those instructions. The instructions needed by the 1024 MB 1 Gigabyte (1GB)
CPU are temporarily stored in the memory. 1024 GB 1 Terabyte (1TB)
- Random Access Memory (RAM): a volatile form of a computer memory.
This memory memorizes temporarily. It can be read and written. A computer with a
large RAM can run faster.
- Read Only Memory (ROM): a non-volatile form of a computer memory. The programs which are
needed to start up the computer are stored in ROM.
- Cache: helps speed the processes by storing frequently used instructions and data thus reducing the
access time of data. When the processor needs an instruction or data, it first searches in the cache.
§ 3.4 – Input Devices
What is input? Any data or instruction you enter to the memory of a computer. The CPU can access it and
process the input into output. Types of input:
- Data: a collection of unorganized facts. A computer manipulates and processes data into information.
- Program: a series of instructions that tells a computer how to perform the tasks necessary to process
data into information. (CD/DVD) Programs respond to commands issued by the user.
- Command: an instruction given to a computer program. Can be issued by typing keywords (a specific
word, phrase or code that a program understands as an instruction) or pressing keys on the keyboard.
- User Response: an instruction which is given by the user to the computer by replying to a question
posed by a computer program. Based on the response, the program performs certain actions.
Input Devices:
- Keyboard: a text-based input device.
- Mouse: a pointing device by detecting two-dimensional motion relative to its supporting surface.
- Scanners: reads printed text and graphics, translates the pattern of light and dark into a digital signal
the computer can store and manipulate.
- Voice input systems
