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CSEC INFORMATION TECHNOLOGY
Administrative and Course Information
The syllabus is divided into eight modules. We will sequentially cover each module. Please note
Module three (3) will be done in the programming language PASCAL.
Duration
CXC has stated that the Syllabus is expected to be covered in 160 hours. At the UWIOC, you
will be completing the syllabus in approximately 105 hours. This means that you have a lot of
work to complete and prioritizing IT will be paramount in determining if you receive a passing
grade.
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**SBA’s will be distributed immediately following the completion of the first term.
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Section 1: Hardware and Software Fundamentals
A basic computer system
Monitor – This is used for displaying a visual interface to the user of the computer
Modem – This device maintains a valid internet connection to the Internet Service Provider (ISP)
Tower/System Unit/ Central Processing Unit – This is responsible for all computing and
processing of applications
Mouse – This is used by the user to interact with objects on the monitor
Speaker – This is used to provide audio output to the user
Printer – This device takes what is displayed on the monitor and creates a physical copy of that
image on paper
Keyboard – This is a device used by the user to input information into the computer
Peripheral Devices: Internal and External
Devices used with a computer system that are not part of the main processing core are referred to
as PERIPHERAL DEVICES and characterised by their primary functions into two categories:
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Internal and External. Can you list four Internal and External devices found on a computer
below?
Internal Device External Device
1
2
3
4
Input Device and Output Device
An Input device takes real world data and translates it into machine readable information for
processing. Likewise, an Output device takes machine readable information and translates it into
a human understandable format. Can you list four input and output devices?
Input Device Output Device
1
2
3
4
Information Processing Cycle
A computer system is capable of four basic major operations: Input, Processing, Storage and
Output.
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Input
This process relates to the entering of data into the system using INPUT DEVICES. (Keyboard,
joystick, mouse, etc.).
Processing and Storage
The system takes the input data and immediately begins to work on it. The system uses
mathematical and logical processes to compute a solution, sometimes transferring data back and
forth between the Storage Unit until the assigned task is completed. After the system computes a
final solution from the processing node, the computed solution is saved to the storage device.
This storage device can be internal hard drive space, a flash drive or any other storage medium.
Output
This process displays the results from the Processing node to an OUTPUT DEVICE. (Screen,
printer, speakers, etc.)
The Central Processing Unit
The CPU is responsible for managing all tasks, computations and operations within the computer
system. This task is so complicated that we need to look at exactly how this is done. The CPU is
made of five interdependent units: Input, Arithmetic/Logical Processing Unit, Memory, Control
Unit and Output.
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The arithmetic logic unit (ALU) performs simple arithmetic and logical operations.
The control unit (CU) manages the various components of the computer. It reads and interprets
instructions from memory and transforms them into a series of signals to activate other parts of
the computer. The control unit calls upon the arithmetic logic unit to perform the necessary
calculations.
Third is the Memory but because it resided within the CPU, we refer to it as cache. This serves
as high-speed memory where instructions can be copied to and retrieved.
STORAGE IN A COMPUTER SYSTEM [Primary and Secondary]
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Primary Storage: Immediate Access Store ( IAS ) , RAM and ROM
IAS holds programs and data that the user is currently working with. For example: A word
processed document that is being edited will be loaded into IAS. An email program that is
currently transmitting a message will be loaded into IAS.
There are two different types of IAS:
Read Only Memory (ROM) : The contents of ROM is permanent. It cannot be altered by the
user. The content is written onto the ROM when it is first made. ROM keeps its contents even
when the computer is turned off and so is known as non-volatile memory. On some computers a
special piece of software called the operating system is stored in ROM. ROM is also often used
in embedded systems where a small built-in computer is used to control a device such as a
washing machine. The program that controls the machine is stored on ROM.
Random Access Memory ( RAM ) : RAM is used to store programs and data that are being used
by the computer. When the computer is turned on the RAM is empty. Data and programs can be
put into RAM from either an input device or backing store. The data in RAM is lost when the
computer is turned off so it is known as volatile memory. To keep data the user must save it to
backing store before the computer is turned off.
The process of transferring data/programs from backing store into RAM so they can be used is
known as loading.
The process of transferring data/programs from RAM to backing store so that they will be
retained when a computer is turned off is known as saving.
Secondary Storage
Alternatively referred to as external memory, secondary memory, and auxiliary storage, a
secondary storage device is a non-volatile device that holds data until it is deleted or overwritten.
Secondary storage is usually cheaper than primary storage per byte. Consequently, hard drives (a
prime example of secondary storage) are the go-to solution for nearly all data kept on today's
computers.
The image shows three types of storage, but off-line storage is a subset of secondary storage as
they both serve the same purpose and do not interact directly with the CPU. The key differences
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being that off-line storage is used as a way to physically transport information, generally has less
capacity, and isn't accessible without human interaction.
Primary Storage Devices
Bistable Device
This is a transistor/electrical device that retain a charge in one of two states. These devices are
the building blocks of memory today. A Bistable device can retain a +5V charge which we refer
to in the digital world as ON or 1, alternatively it could retain a lesser charge or no charge and
we refer to it as OFF or 0.
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Units of Storage
Bit
The smallest unit of data in a computer is called Bit (Binary Digit). A bit has a single binary
value, either 0 or 1. The value of a bit is usually stored as either above or below a designated
level of electrical charge within a memory device. For example, +5V representing ON or 1 OR
0V representing OFF or 0. A bit is abbreviated with a small “b”
Nibble
Four bits is called a nibble.
Byte
A byte is a unit of data that is eight binary digits long. A byte is the unit most computers use to
represent a character such as a letter, number or typographic symbol (for example, “g”, “5”, or
“?”). In some computer systems, four bytes constitute a word, a unit that a computer processor
can be designed to handle efficiently as it reads and processes each instruction. A byte is
abbreviated with a “B”. Computer storage is usually measured in byte multiples. For example, an
820 MB hard drive holds a nominal 820 million bytes – or megabytes – of data. Byte multiples
are based on powers of 2 and commonly expressed as a “rounded off” decimal number. For
example, one megabyte (“one million bytes”) is actually 1,048,576 (decimal) bytes.
Octet
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In some systems, the term octet is used for an eight-bit unit instead of byte. In many systems,
four eight-bit bytes or octets form a 32-bit word. In such systems, instructions lengths are
sometimes expressed as full-word (32 bits in length) or half-word (16 bits in length).
Kilobyte
A Kilobyte (kb or Kbyte) is approximately a thousand bytes (actually, 2 to the 10th power, or
decimal 1,024 bytes).
Megabyte
As a measure of computer processor storage and real and virtual memory, a megabyte
(abbreviated MB) is 2 to the 20th power byte, or 1,048,576 bytes in decimal notation.
Gigabyte
A Gigabyte (pronounced Gig-a-bite with hard G’s) is a measure of computer data storage
capacity and is “roughly” a billion bytes. A gigabyte is two to the 30th power, or 1,073,741,824
in decimal notation.
Terabyte
A Terabyte is a measure of computer storage capacity and is 2 to the 40th power of 1024
gigabytes.
Petabyte
A Petabyte (PB) is a measure of memory or storage capacity and is 2 to the 50th power bytes or,
in decimal, approximately a thousand terabytes (1024 terabytes).
Exabyte
An Exabyte (EB) is a large unit of computer data storage, two to the sixtieth power bytes. The
prefix exa means one billion billion, or on quintillion, which is a decimal term. Two to the
sixtieth power is actually 1,152,921,504,606,846,976 bytes in decimal, or somewhat over a
quintillion (or ten to the eighteenth power) bytes. It is common to say that an Exabyte is
approximately one quintillion bytes. In decimal terms, an Exabyte is a billion gigabytes.
Zettabyte
A Zettabyte (ZB) is equal to one sextillion bytes. It is commonly abbreviated ZB. At this time,
no computer has one Zettabyte of storage. It has 1024 Exabytes.
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Yottabyte
A Yottabyte is equal to one septillion bytes. It is commonly abbreviated YB. At this time, no
computer has one Zettabyte of storage. It has 1024 Zettabytes
Secondary Storage Devices
Magnetic Tape
This is a sequential storage medium used for data collection, backup and archiving. Like
videotape, computer tape is made of flexible plastic with one side coated with a ferromagnetic
material. Tapes were originally open reels, but were superseded by cartridges and cassettes of
many sizes and shapes. Tape has been more economical than disks for archival data, but that is
changing as optical disk capacities have increased enormously. If tapes are stored for the
duration, they must be periodically recopied or the tightly coiled magnetic surfaces may
contaminate each other. Due to the large size of tape reels, these storage devices were not readily
portable.
Floppy Disk
A floppy disk, also called a diskette or just disk, is a disk storage medium composed of a disk of
thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with
fabric that removes dust particles. Floppy disks are read and written by a floppy disk drive
(FDD) and had a maximum of 1.44MB of memory. These were readily portable than magnetic
tape. This is a direct access storage device.
Optical Disk (CD/DVD)
CD/DVD’s are metal and plastic composed optical disks that stores data on circular tracks on
one side of a CD/DVD. A special beam of light (laser) is shone onto the reflective side of the CD
and the computer is able to read the information stored on the disk. A CD can hold about 700MB
of information whereas a DVD can store about 4GB of information. Though this medium was
larger than floppy disks, the demands of today are making these devices obsolete and they are
clumsy to walk around with now. This is a direct access storage device.
Trivia Time: What does the acronym CD and DVD stand for?
Universal Serial Bus (USB) Drive
This is a solid state device that requires no moving parts to store data. The USB drive consists of
many transistors that are packaged close together on microchips that are all connected onto a
small circuit board. The USB utilises the flash/EEPROM type of memory. USB drives are
plugged into USB ports on computers for reading or writing data to them. The physical size of a
USB drive is much smaller than a CD/DVD and they can store much more data. USB drives can
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be as large as 512GB although rumours of 1TB USB drives are circulating online. This is a direct
access storage device.
Flash Memory Cards
These cards utilise the EEPROM memory medium and come in many differing sizes and shapes.
This form of memory is usually found in portable devices like cameras and cell phones. This is a
direct access storage device.
Hard Drives
These are the most economical form of mass storage for computers today. HDD’s come in
different flavours based on a number of factors like size, reliability, speed and affordability. This
is a random access storage device.
Moving Head HDD
Internally, a hard drive consists of a platter that spins on an axis while an access/read head scans
over the platter to read and write data to the drive. Hard Drives can come in sizes beyond 5TB
and this limit is increasing daily as advances are made in HDD technology.
Fixed Head HDD/Head per Track HDD
These HDD carried one read/write head per track on the platter. This meant that time was saved
because the head did not need to move to the requested track to read/write data. Due to the
number of read/write heads these drives were expensive to manufacture are they are no longer in
production.
Solid State HDD
These types of hard drives are referred to as solid state devices as there is no read/write head.
The drive consists of EEPROM microchips that are more reliable that a spinning platter. Due to
the cost of these EEPROM chips, these drives tend to cost more than regular platter HDD’s.
External HDD
These are drives that connect to the outside of the computer via an interface port (USB, eSATA,
Firewire or iSCSI). These drives are handy for moving data from PC to PC and come in many
sizes, shapes and speeds.
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Storage Devices Terms
Read/Write Head
Disk read/write heads are the small parts of a disk drive, that move above the disk platter and
transform the platter's magnetic field into electrical current (read the disk) or vice versa –
transform electrical current into magnetic field (write the disk).
Sectors, Tracks and Clusters
On a hard disk, data is stored in thin, concentric bands. A drive head, while in one position can
read or write a circular ring, or band called a track. There can be more than a thousand tracks on
a 3.5-inch hard disk. Sections within each track are called sectors. A sector is the smallest
physical storage unit on a disk, and is almost always 512 bytes (0.5 kB) in size. A cluster can
consist of one or more consecutive sectors. The number of sectors is always an exponent of 2.
Homework
Question
Create a document on your computer which briefly examines the history of computers. Clearly
state all of the generations of computers and give two examples of the computers found within
each generation where possible.
Requirements
You response should be no more than two pages. Pictures are encouraged but should be kept to a
minimum. Font set should be 12pt and Times New Roman with justified paragraphs. Margins
should be 0.5 inches all around and all headings should be clearly visible from the rest of your
document. All pages must be numbered. Your submission should carry a front page with the
current Date, Your Name, ID Number, Course Name, Instructor and Site (UWI OC Barbados -
Pine)
References
Menkin, P. (2001). Storage, Immediate Access Store. Retrieved from
http://www.thomastallis.greenwich.sch.uk/gcse/gcseict3/online/artstrr.htm. Accessed 14th
September 2015.
Unknown (?).Secondary Storage Device. http://www.computerhope.com/jargon/s/secostor.htm.
Accessed 14th September 2015.
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Microsoft. (2015). USB Device. Retrieved from http://windows.microsoft.com/en-
us/windows/what-is-usb-flash-drive#1TC=windows-7. Accessed 15th
September 2015
Wikipedia.(2015). Floppy Disks. Retrieved from https://en.wikipedia.org/wiki/Floppy_disk .
Accessed 15th
September 2015. pp 1.
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