ICT (Computer Studies) for High School

OVERVIEW OF COMPUTER HARDWARE

A computer may be defined as a machine that can solve problems by accepting data, performing certain operations and presenting the results of those operations under the direction of detailed step-by-step instructions.

Constituents of a Computer

A computer consists of hardware and software.         The hardware is the physical part of the computer that can be seen and touched.

The basic set of hardware found in most PCs are:

1.      PC Case

2.      Motherboard

3.      Power Supply

4.      Hard Disk Drive (HDD)

5.      Floppy Disk Drive (FDD)

6.      Compact Disk Drive (CDD)

7.      Digital Video Disk Drive (DVD)

8.      Monitors (CRT and LCD)

9.      Keyboard

10. Mouse

11. Audio

12. Cables and wires.

Hardware can be broadly divided into two parts namely: System Unit and Peripherals.

·         System Unit or Computer case is the part of a computer that houses the primary devices that perform operations and produce results for complex calculations. It includes the motherboard, CPU, RAM and other components, as well as the case in which these devices are housed.

          

·         Peripherals are devices that are used to put information into or get information out of a computer. Some types of peripherals are:

a.     Input devices (mouse, keyboards etc.)

b.     Output devices (monitors, printers etc.)

c.     Storage devices (hard drives, flash drives, etc.)

Exercises:

1.      What is a computer?

2.      What are the two main components of a computer?

3.      What is hardware?

4.      What are seven examples of computer hardware components?

5.      What are the differences between system unit and peripherals?

Topic: Computer Data Conversion (1)

Data conversion is the conversion of computer data from one format another

COMPUTER DATA CONVERSION

REGISTERS

Registers are temporary storage area for instructions or data. They are not a part of memory; rather they are special additional storage locations that offer the advantage of speed. It works under the direction of the control unit to accept, hold, and transfer instructions or data and perform arithmetic or logical comparisons at high speed. Most operations are done on the register; the processor can’t directly perform arithmetic in memory. For example, if you want to add 1 to a memory address, the processor will normally do this by loading the initial value from memory into a register, adding 1 to the register, and then saving the value back to memory.

The width (in bits) of the processor’s register determines how much data it can compute with at a time. This is sometimes used to label the processor’s size.

ADDRESS

A memory address is an identifier for a memory location, at which a computer program or a hardware device can store data and later retrieve it. In modern byte – addressable computers, each address identifies a single byte of storage; data too large to be stored in a single byte may reside in multiple bytes occupying a sequence of consecutive addresses. Some microprocessors were designed to be word – addressable, so that the addressable storage unit was larger than a byte. The efficiency of addressing of memory depends on the size of the address bus.

In a computer program, an absolute address, (sometimes called an explicit address or specific address), is a memory address that uniquely identifies a location in memory. This is different from a relative address, which is not unique and specifies a location only in relation to somewhere else (the base address). Virtual memory also adds a level of indirection. Very often, when referring to the word size of a modern computer, one is also describing the size of virtual memory addresses of that computer. For example, a computer said to be “32 bits” usually treats memory addresses as 32 – bit integers; a byte addressable 32 – bit computer can address 2³² = 4,294,967,296 bytes of memory or 4 gigabyte.

BUS

A bus, in computing is a set of physical connections (cables, printed circuits etc.) which can be shared by multiple hardware components in order to communicate with one another. The purpose of bus is to reduce the number of pathways needed for communication between the components, by carrying out all communications over a single data channel.

CHARACTERISTICS OF BUS

A bus is characterized by the amount of information that can be transmitted at once.

Width is used to refer to the number of bits that a bus can transmit at once.

Frequency is the speed of the bus, which is the number of data packets sent or received per second. It is expressed in Hertz (Hz).

Cycle is refers to each time that data is sent or received.

Transfer speed is the amount of data which it can transport per unit of time. It is the product of width and frequency.

BUS SUBASSEMBLY

Each bus is generally constituted of 50 to 100 physical lines, divided into three subassemblies which are:

(i)                 Address bus (sometimes called memory bus) transports memory addresses which the processor wants to access in order to read or write data. It is unidirectional bus.

(ii)               Data bus transfers instructions coming from or going to the processor. It is bidirectional bus.

(iii)             Control bus (or command bus) transports orders and synchronisation signals coming from the control unit and travelling to all other hardware components. It is bidirectional bus, as it also transmits response signals from the hardware.

PRIMARY BUS

There are two buses within a computer;

Internal bus (also known as front – side bus (FSB)) allows the processor to communicate with the system’s central memory (RAM).

Expansion bus (also known as input/output bus) allows various motherboard components to communicate with one another. However, it is mainly used to add new devices using what are called expansion slots connected to the input/output.

Exercises:

1.      What is data conversion?

2.      What is a register?

3.      What is a bus?

4.      What determines how much data a processor can compute at a time?

5.      What is a cycle?

6.      What is transfer speed?

7.      What is a memory address?

8.      What does a bus consist of?

9.      What does the control bus do?

10.  What are the names of the two buses within a computer?

Topic: Computer Data Conversion (2)

TYPES OF REGISTER

   (a)   MDR (Memory Data Register)

This is the register of a computer’s control unit that contains the data to be stored in the computer storage (e.g. RAM), or the data after a fetch from the computer storage. It acts like a buffer and holds anything that is copied from the memory ready for the processor to use it.

The MDR is a two – way register because when data is fetched from memory and placed into the MDR, it is written to in one direction. When there is a write instruction, the data to be written is placed into the MDR from another CPU register, which then puts the data into memory.

    (b)   CIR (Current Interrupt Register)

It captures the value that is winning the interrupt arbitration. The CIR is updated at the beginning of an interrupt acknowledge bus cycle or in response to an update CIR command. The contents remain in the CIR until another interrupt acknowledge cycle or update CIR Command occurs.

   (c)    User – Accessible Register: The most common division of user – accessible registers is into data registers and address registers.

   (d)   Data Registers: They are used to hold numeric values such as integer and floating – point values.

   (e)    GPRs (General Purpose Registers): They can store both data and addresses.

   (f)     FPRs (Floating Point Registers): They store floating point numbers in many architectures.

   (g)   Constant Registers holds read – only values such as one, or pi.

   (h)   Special Purpose Registers: They hold program state

   (i)     Instruction Registers store the instruction currently being executed.

   (j)     Model – Specific Register (also known as machine – specific register) store data and settings related to the processor itself.

   (k)   Control and status register: It has three types which are program counter, instruction register and status word (PSW).

Exercises:

1.      What is MDR?

2.      What acts like a buffer in the register?

3.      What is CIR?

4.      Logically differentiate MDR from CIR.

5.      What are the differences between data registers and general purpose registers?

6.      Name and briefly describe five types of registers.

Research:

Define the following terms:

·         Register

·         Address

·         Bus

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Topic: Computer Data Conversion (3)

DIFFERENCES BETWEEN REGISTERS AND MAIN MEMORY

	REGISTER	MAIN MEMORY
1	Registers are very small but are extremely fast.	RAM is much larger and smaller memory that applications use as a scratch space.
2	It holds data temporary	It holds information/data permanently
3	It serves as an assistance to the main memory	It does not assist
4	It is an extremely fast and expensive form of computer memory.	It is much cheaper.

 DATA – FETCH – EXECUTE CYCLE

John Von Neumann introduced the idea of the stored program. Previously data and programs were stored in separate memories. Von Neumann realized that data and programs are indistinguishable and can therefore use the same memory. This led to the introduction of compliers which accepted text as input and produced binary code as output.

The Von Neumann architecture uses a single processor which follows a linear sequence of fetch – decode – execute. In order to do this, the processor has to use some special registers.

DATA TRANSFER SPEED

Computer data bus width indicates how much data the chip can move through at once and the sizes of address bus indicates how much the memory chip can handle.

Increasing the data bus will increase the quantity of data that the bus carry at one time and so speed up the performance/processing of the computer. A computer with a data bus of 32 lines is called 32 bits computer and the word length is 32 bits.

Word length is the number of bits the CPU can process in a single operation.

Exercises:

1.      State three differences between registers and main memories.

2.      List some factors affecting speed of data transfer.

3.      What is word length?

4.      Who introduced the idea of the stored program?

5.      What led to the introduction of compliers which accepted text as input and produced binary code as output?

6.      What is a 32 bit computer?

Topic: Concepts of Computer files (1)

What is a File?

A file, in the computer world, is a self-contained piece of information available to the operating system and any number of individual programs.

Information inside the file could consist of essentially anything but whatever the file contains is likely related somehow.
A computer file can be thought of much like a traditional file that one would find in an office's file cabinet.

Definition of some terms:

1.       A Computer file is a specific piece of data held on a computer system. A file is a collection of related data items

2.       Fields are the physical arrangement of data items in a computer file. Fields have fixed or variable lengths...

3.       Records are collections of related data items or fields.

4.       Data items are the smallest unit of information stored in a computer file. A data item is a single element used to represent a fact such as a student’s name, admission number, age, etc.

Types of Data Items

1.       Numeric: this consists of numbers 0 – 9

2.       Alphabet: this data type consists of letters A – Z.

3.       Alphanumeric (sometimes simply called ‘alphameric’): is a combination of both numeric and alphabet characters, and is used to describe the collection of Arabic digits and Latin letters or a text constructed from this combination.

File Structure

DATA

FIELD

RECORD

FILE

Types of file organization Methods

Serial File organisation

Serial file organisation is the simplest type of file organisation. The records are arranged one after another in the order in which they were added. That is, they have been sorted into any particular order. Examples of serial files (also called unordered files). A serial file is mainly used for backup purposes and is stored on tape or disk.

Examples of serial files

1.      Unsorted invoices for customers

2.      Collection of student marks

3.      Shopping list

Sequential File organisation

A sequential file is one in which the records are stored in sorted order on one or more key fields.

Examples of sequential files

1.      Invoices for customers sorted on customer number

2.      Class registers sorted on last name

v  NOTE: Searching for a particular file in a sequential file organization, means all the preceding records must be read.

v  The main disadvantage to inserting, deleting or updating records in both serial and sequential files is that the entire file must be read and then the records written to a new file.

Indexed Sequential File organisation

An indexed file is used to speed up the key search in a file. You can think of it as a one –column table organised in ascending order and stored on disk. The primary key in the table is used as an index to the record.

Random file organization

This is the arrangement of files via ‘index’. This method is also called ‘direct file’ or a ‘direct access file’.  Random file organization enables quick access to specific records or other elements within the file rather than having to read the file sequentially.

v  Random file organization is the most efficient way of storing extremely large files, such as National databases.

Files have three important characteristics

1.      Whether the file is permanent or temporary

2.      The way the records are organized – sequential, or serial

3.      Method of access or location – sequential or direct access

Exercises:

1.      Define the following terms:

(a)  File

(b)  Data item

(c)  Record

(d)  Field 

2.      What is the simplest type of file organization?

3.      What is a serial file particularly used for?

4.      What are the three types of data items?

5.      Describe the file structure.

6.      What are the differences between the various methods of file organization?

7.      What is random file organization?

Topic: Concepts of Computer files (2)

Methods of accessing files

Serial Access: simply put, the only way to access a serially organized file is serially.

Sequential Access: A simple access method, information in a file is accessed sequentially one record after another.

Sequential access is based on the tape model that is inherently a sequential access device. Sequential access is best suited where most of the records in a file are to be processed. For example, transaction files.

Direct Access: Sometimes it is not necessary to process every record in a file. It may not be necessary to process records in the order in which they are present. Information present in a record of a file is to be accessed only if some key value in that record is known. In all such cases, direct access is used.

Direct access is based on the disk that is a direct access device and allows random access of any file block. Since a file is a collection of physical blocks, any block and hence the records in that block are accessed. For example, master files. Databases are often of this type since they allow query processing that involves immediate access to large amounts of information. All reservation systems fall into this category.

Not all operating systems support direct access files. Usually files are to be defined as sequential or direct at the time of creation and accessed accordingly later. Sequential access of a direct access file is possible but direct access of a sequential file is not.

Indexed Sequential Access: This access method is a slight modification of the direct access method. It is in fact a combination of both the sequential access as well as direct access.

The main concept is to access a file direct first and then sequentially from that point onwards. This access method involves maintaining an index. The index is a pointer to a block.

To access a record in a file, a direct access of the index is made. The information obtained from this access is used to access the file.

For example, the direct access to a file will give the block address and within the block the record is accessed sequentially. Sometimes indexes may be big. So hierarchies of indexes are built in which one direct access of an index leads to info to access another index directly and so on till the actual file is accessed sequentially for the particular record.

The main advantage in this type of access is that both direct and sequential access of files is possible.

Random Access: Random files are accessed ‘randomly’. The transaction record keys are put through the same mathematical formula as were the keys of the master records, thus creating the appropriate bucket address.  The transactions in random order are then processed against the master file, the bucket address providing the address of record required.

Classification of Computer Files

Master File: This is a permanent file which is kept up to date and stores the main information, summary data and key fields in the data. Examples of such files are payroll, inventory and customer ledge.

The master file contains two types of data:

·         Permanent data such as personal files, payroll data, employee status (contract, permanent or temporary) and job title.

·         Less permanent data such as taxes deducted, hours worked, bonuses received.

Transaction File: This is a temporary file which is used to update the master file after a certain time; usually at the end of the day or at the end of the week. They are also known as movement files.

Transaction files perform three important tasks:

·         Add a new record to the master file

·         Update or change the contents of a record or field.

·         Remove records from the master file such as employee dismissal.

All changes in the transaction file are recorded in another file called the transaction log or the change file.

Reference files: this is a file with a reasonable amount of permanency. Common examples are names, addresses, price lists and tables of rates of pay,

Exercises:

1.      What is the difference between serial and sequential file organization

2.      Give an example of a file that would be organized sequentially

3.      On what is sequential access based?

4.      On what is direct access based?

5.      What is a reference file?

OVERVIEW OF COMPUTER HARDWARE

A computer may be defined as a machine that can solve problems by accepting data, performing certain operations and presenting the results of those operations under the direction of detailed step-by-step instructions.

Constituents of a Computer

A computer consists of hardware and software.         The hardware is the physical part of the computer that can be seen and touched.

The basic set of hardware found in most PCs are:

1.      PC Case

2.      Motherboard

3.      Power Supply

4.      Hard Disk Drive (HDD)

5.      Floppy Disk Drive (FDD)

6.      Compact Disk Drive (CDD)

7.      Digital Video Disk Drive (DVD)

8.      Monitors (CRT and LCD)

9.      Keyboard

10. Mouse

11. Audio

12. Cables and wires.

Hardware can be broadly divided into two parts namely: System Unit and Peripherals.

·         System Unit or Computer case is the part of a computer that houses the primary devices that perform operations and produce results for complex calculations. It includes the motherboard, CPU, RAM and other components, as well as the case in which these devices are housed.

           

 

·        Peripherals are devices that are used to put information into or get information out of a computer. Some types of peripherals are:

a.     Input devices (mouse, keyboards etc.)

b.     Output devices (monitors, printers etc.)

c.     Storage devices (hard drives, flash drives, etc.)

Exercises:

1.      What is a computer?

2.      What are the two main components of a computer?

3.      What is hardware?

4.      What are seven examples of computer hardware components?

5.      What are the differences between system unit and peripherals?

Research:

1.      What is CPU?

2.      What is the purpose of the CPU?

3.      Who made the world first CPU? In what year?

4.      What is Intel 8008?

  

Topic: Document Production – set fonts as specified, set alignment for the text line spacing

Document production is best done on Microsoft Word. Ms-Word is a word processor having many facilities even for Internet and Clip Art. It is an efficient and full-fledged word processor that provides you with all the tools you need to produce a variety of documents.

Moving around the document

Use the following combination of keys to move the document:

Key Combination	Movement
Home	Move to the beginning of the line
End	Move to the end of the line
Ctrl  + Right arrow	Move one word to the right
Ctrl  + Left arrow	Move one word to the right
Ctrl  + Up arrow	Move to the previous paragraph
Ctrl + . (period)	Move to the next sentence
PgUp (page Up)	Move up one window
PgDn (page down)	Move down one window
Ctrl + PgUp	Move up one page
Ctrl + PgDn	Move down one page
Ctrl + Home	Move to the top of the document
Ctrl + End	Move to the bottom of the document

Changing font

Font is a collection of letters, numbers, and special characters that contain the same typeface, thickness and size.

·         The size of font is measured in points.

·         One point is 1/72^nd of an inch.

·         Word displays the current font name on the formatting toolbar.

To change the font, do the following:

·         Select the text as explained before.

·         Click the drop down arrow to the right of the Font Name box.

·         Use the scroll bar in the font name box to select a different font.

·         Click on the font to select.

Alignment

Alignment means placement of text within a column. When you first start typing in a document, all the text begins at the left margin and moves to the right as you type.

Types of alignment:

1.      Left justified: the default justification for the normal text, aligned to the left.

2.      Right justified: text is aligned at the right margin, and text lines show a ragged left edge.

3.      Center: the text is centered between the left and the right margins of the page.

4.      Full Justification: the text is justified on both the left and the right, so text is aligned at both the left and right margins.

The easiest way to change the alignment of text in the document is to use the alignment buttons of the Formatting toolbar. You can also use the Alignment  drop down list from the Paragraph dialog box. Choose one of the Alignments to apply the changes.

v   

Alignment short cuts:

·         Left align – Control + L

·         Right align – Control + R

·         Centre align – Control + E

·         Full justification – Control + J

Class activity: Type the passage shown below. Align it using the four patterns of alignment. Use any font of your choice.

Exercises:

1.      What is document production?

2.      What is ‘Word’?

3.      What are the short cuts used in document production?

4.      What is font?

5.      How can a font be changed or formatted?

6.      What is alignment in document production?

7.      What are the four ways of aligning a document?

8.      What are the short cuts for aligning a document?

 

Presentation Authoring – presentation page, set up presentation, master slide

Presentation is the practice of showing and explaining the content of a topic to an audience or learner.

A Presentation Package is a software which is used to generate a presentation content.

Examples of presentation software:

1.      PowerPoint

2.      OpenOffice.org Impress

Using the Themes Wizard

1.      Go to File.

2.      Click on New.

3.      Click on Themes.

4.      Browse through the themes then Select any that suites the presentation of your choice.

5.      Click on Create

6.      Your presentation theme is ready. All you need do now is to edit the texts and images to your preferred choice.

Using a Template

To start a new presentation using a design template, follow these steps:

1.      Open the File>New. The New Presentation task pane appears.

2.      Click on Sample Templates button under New area.

3.      Browse through the templates using the scroll bar.

4.      Click a template that you like.

5.      After you select the template you want to use, PowerPoint applies the template to all the slides in the presentation.

Exercise:

1.      What is presentation?

2.      What is a presentation package?

3.      What are two examples of presentation software?

4.      How can theme wizard be used to make PowerPoint presentations?

5.      How can templates be used when making presentations?

Presentation Authoring – use of graphical information, presentation page, transition

PowerPoint offers various tools to create a drawing in PowerPoint itself. These tools are available on the Insert toolbar in PowerPoint. With this toolbar you can easily add graphics to your presentation.

This toolbar makes it easy for you to add Tables, Pictures, Clip Arts, Screenshots, Photo Albums, Shapes, SmartArt and Charts to your presentations.

In the Home toolbar, there is a drawing section towards the right hand side. The Drawing section you see there can also be used to add graphics to your presentation.

Adding a Chart Slide

 
The Chart Wizard button on the standard toolbar enables you to quickly create a chart. To use the Chart Wizard, follow these steps:

1.      Click the Chart Wizard button.

2.      Choose the chart pattern of your choice.

3.      You will be presented with a readymade Bar Chart and a datasheet with readymade data.

4.      Type in the data you want to chart. Type column and row labels. (such as Qtr 1, Qtr 2 etc) that you want included in the chart. Delete any data available in the readymade datasheet. Observe the changes taking effect in the graph on the slide.

5.      Format your graph using the menus and the toolbars. Graph works like a stripped-down version of Excel.

6.      You can always edit the bar titles to suit your purpose.

7.      Close the datasheet by clicking its Close button.

8.      To return to the slide click elsewhere in it.

Class activity:  Design a PowerPoint presentation depicting a chart. Choose any topic of your choice (ranging from banking, economics, population, medicine to education). Be versatile and very creative.

Exercises:

1.      How can graphics be added to a PowerPoint presentation?

2.      What are the names of five tools on the Insert Toolbar?

3.      How can Chart Wizard be used to add chart to a presentation?