SS 2 COMPUTER SCIENCE, EASTER TERM, LESSON 1: COMPUTER FILES.
A file is a collection of data or information that is related to each other I.e. it is a collection of related documents or papers that are arranged so that they can be consulted at ease.
Therefore, a computer file is a digital data that contains stored information, and stored in computer readable form. A file is a named collection of bits, usually stored on a disk; it possesses some properties such as size, owner, type, name, etc.
A computer file is a digital information stored in a computer file format (electronic format) which is available to a computer programmer and is based on some kind of durable storage.
Computer files may be stored on the RAM, ROM, hard disk, CD-ROM, floppy disks, micro disks, flash disk, magnetic tapes, etc. Almost all information stored on computers is in the form of files.
Anytime the CPU (central processing unit) needs data from a file, it or when it requires to write data to a file, it keeps the file temporarily in its memory (I.e. tandom access memory) before working on the data and it later saves the data into a permnanent location when instructedvby the user.
A record is an account of an event or something preserved in a lasting form that can be consulted in future. A record is a written account of proceedings of something or an event.
In computer science, a record is also a collection of related items of information treated as a unit by a computer.
A record is a block of data read and written at one time without any relationship to records in a file. A record can also be a group of logical related fields regarded as a unit.
A field is an element of a database record in which a piece of information is stored. It can also be defined as an area of storage medium (usually a set of adjacents columns) used to record a type of information.
A data item is a single member of a data element. It is a unit of stored data in a field. It can also be regarded as a sub-unit of descriptive information.
Types of data items
Types of data items explain the various data that are commonly used in computer data processing. Computer data types are necessarily translated into machine-readable form of binary digits(0,1) before they can be processed.
Common data item types are:
1. Numeric data
2. Alphabetic data
3. Alpha-numeric data
4. Audio data.
It should be noted that in computer data is stored as binary numbers. All the data types are converted back to binary digits before they are processed and stored.
Numeric data is data consisting of digits (numbers or figures) and not letters or special characters. Numeric data can be used for calculations. They also include numeric notations.
Example: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, $50, £20,>, <,+, -, %!( factorial).
These are data types in form of letters as opposed to numbers or numeric dats. They also include alphabetic notations. They cannot be used for calculations. Examples, A, B, C, D, Z, ?,!.(exclamation marks).
This is a data type in form of letters and numbers( combination of numbers and alphabetic dats). They cannot be used for calculations. Examples: 20 km, 50k, plot 2 Flat 4.
File structure on the computer. Computer files are arranged in order. File are grouped into folders and a sub-folder can be created in a folder where in files can be kept.
To understand file structure, consider a hard disk drive to be a filing cabinet where file are kept for future use. A filing cabinet has dividers or drawers and folders within the dividers. The hard disk drive (driveC) is similar to the filing cabinet. The dividers can be likened to directories. There are sub-folders where in files are kept. The default shape of the windows folder is ‘yellow file’ shape. The windows explorer reveals a comprehensive file structure on a computer. It shows the (drives). (C:, A:, D:, E:, F:, etc) directories or folders, sub-folders, etc. When entries of data are made on the computer, they are temporary kept inside the RAM where the data are being handled for processing. The data inside the RAM is volatile, I.e.it is lost when there is power outage.
SS2 COMPUTER SCIENCE, EASTER TERM, LESSON 2. File organization File organization is the method of arrangement of files in a storage medium. File organization can also be referred to as the technique of physically arranging records of a file in a storage media. In relation to computer, file organisation is the process or technique of …. Read More
SS2 COMPUTER SCIENCE, EASTER TERM, LESSON 3. BASIC CACULATION FORMULA FOR FILE ORGANISATION 1 File transfer rate = size of file in characters over transfer rate 2. Number of records per tracks required = Bytes per tracks over character per records. 3. Number of tracks required =Number of records over Number of records per track. …. Read More
SS2 COMPUTER SCIENCE, EASTER TERM, LESSON 4, WORD PROCESSING Lesson Preamble This lesson discusses the essentials of word processing in our daily activities. Almost all offices and homes carry out word processing jobs every day. Word processing is the creation, input, editiing, and production of documents and texts by means of a computer system using …. Read More
YHWH HAMASCHIAC SCHOOL TERM: Easter Term Examination CLASS: SS2 COURSE: Computer Science TIME/DATE: 2Hours. 30th March 2021 INSTRUCTIONS: This examination instrument on Computer Science consist of six questions to answer four. Also, it is made of only ‘Section A’. 1. State and explain three features of a Microsoft word processing environment. 10Marks 2. List five …. Read More
SS2 COMPUTER SCIENCE, SPRING TERM, LESSON ONE( EASTER TERM RECAP/REVISIONS). 1). SS2 COMPUTER SCIENCE EXAMINATION ANSWERS 1. State and explain three features of a Microsoft word processing environment. 1. Title bar-This bar displays the title of the program and the document being worked on. 2. Sizing bar: It contains three buttons that are used for …. Read More
SS2 COMPUTER SCIENCE, SPRING TERM, LESSON TWO….THE SYSTEM DEVELOPMENT CYCLE . Introduction The need to develop a system usually results from two situations. These situations could either be a conversion from a current manually operated system or an improvement in an existing computerised system for the purpose of addressing inadequacies seen in it. Regardless whether …. Read More
SPRING TERM, SS2 COMPUTER SCIENCE, LESSON THREE……THE SYSTEM DEVELOPMENT CYCLE (c). System Implementation This is the stage at which a new system is put in place. The success or failiur of this stage depends on the planning that was done at the start of the system development cycle. A good planning would have considered the …. Read More
SS2 COMPUTER SCIENCE, SPRING TERM, LESSON FOUR…..PROGRAM DEVELOPMENT. Introduction The computer is an electric machine that can be programmed. It works with the facts that are put into it, called data, which are processed, and give out information that can be temporary or permanently used. This means that the computer requires programs to function, typically …. Read More
SS2 COMPUTER SCIENCE, SPRING TERM, LESSON FIVE…..PROGRAMME DEVELOPMENT. Precaution to be taken when writing a program. 1. The program code should be as short as possible for the execution time to be less. 2. Accuracy: A good program must possess correctness with goal of the program. 3. Readability-A good program must be readable both to …. Read More
SSS2 COMPUTER SCIENCE, SPRING TERM, LESSON SIX…..PROGRAM DEVELOPMENT. Introduction The computer is an electric machine that can be programmed. It works with the facts that are put into it, called data, which are processed, and give out information that can be temporary or permanently used. This means that the computer requires programs to function, typically …. Read More
SSS2 COMPUTER SCIENCE, SPRING TERM, LESSON SEVEN………..PROGRAM DEVELOPMENT. Introduction The computer is an electric machine that can be programmed. It works with the facts that are put into it, called data, which are processed, and give out information that can be temporary or permanently used. This means that the computer requires programs to function, typically …. Read More
SSS2 COMPUTER SCIENCE, SPRING TERM, LESSON EIGHT…..NETWORK CABLES AND CONNECTOR. Network Cables and connectors Networking cables are used to connect one network device to another. Cables There are different types of cables. These include twisted pair, coaxial Fibre optic and telephone cable. Twisted pair , It is the most widely used medium for telecommunication. Twised-pair …. Read More
SSS2 COMPUTER SCIENCE, SPRING TERM, LESSON NINE…….NETWORK CABLES AND CONNECTION. Forms of databases There are many forms of database organization. However for the purpose of this lesson, we are going to deal with only the three common data. These are hierarchical, network and relational. Hierarchical database: In a hierarchical database, fields or records are structured …. Read More
SSS2 COMPUTER SCIENCE SPRING/THIRD TERM AREAS OF CONCENTRATION TO BE READ FOR THE CONTINUOUS ASSESSMENT TEST: Lesson4. Lesson 7. Lesson 8.
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YHWH HAMASCHIAC INTERNATIONAL SCHOOL. TERM. Spring/Third Term Subjects: Computer Science Examination. Class: SSS 2, Time: 2Hours Guide:. Answer only four questions in all. (1a). system development is usually a reaction to some forces of change. List and elaborate three forces of system development. (1b). What is system development?. (2a). State four features of a good …. Read More
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