WAEC SSCE - Computer Studies - 2019

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A scanner and a floppy disk are respectively an input device and a storage device. A scanner is a device used to convert a physical document or image into a digital format. It works by using a light source to capture an image and then digitize it. This means that it takes information from the physical world and converts it into a form that a computer can understand and process, making it an input device. On the other hand, a floppy disk is a type of removable storage device used to store and transfer data. It works by using magnetic storage to store data on a disk that can be easily removed and used in another computer. This means that it takes information from the computer and stores it in a physical form that can be accessed later, making it a storage device.

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The input device that converts an image into text is known as an Optical Character Reader (OCR). OCR is a technology that uses specialized software to recognize text characters within an image and then converts them into a digital format that can be edited, searched, and processed like any other text data. OCR technology can be used for a variety of applications such as digitizing printed documents, translating languages, and recognizing handwritten text. In summary, an OCR is a tool that helps to convert an image of printed or handwritten text into digital text that can be easily edited and manipulated.

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The effects of file insecurity include virus infection, file corruption, and data loss. However, encrypted data is not an effect of file insecurity. When files are insecure, they can be easily infected by viruses and malware, which can cause harm to the computer and compromise sensitive data. File corruption can occur due to various reasons such as hardware failure, software errors, or virus attacks. This can lead to files becoming unreadable or unusable, which can cause significant inconvenience and loss of important information. Data loss is also a common effect of file insecurity, which can occur due to accidental deletion, system failure, or hardware damage. Encrypted data, on the other hand, is a security measure that is used to protect files and data from unauthorized access. It is not an effect of file insecurity, but rather a way to prevent file insecurity from happening. Encryption involves converting the original data into a code that is unreadable without a specific decryption key. This helps to ensure that sensitive data is kept safe and secure, even if the files themselves are compromised.

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In BCD (Binary Coded Decimal) encoding system, 25 will be represented as 00100101. BCD is a system that represents each digit of a decimal number with its equivalent binary code. In BCD, each decimal digit is represented by a four-bit binary code. Therefore, the decimal number 25 is represented in BCD as follows: The binary representation of 2 is 0010, and the binary representation of 5 is 0101. So, combining the binary codes for both digits, we get 0010 0101, which is equivalent to the decimal number 25 in BCD representation. Therefore, the correct option is 00100101.

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Spreadsheet packages are software programs that allow users to create, manipulate and analyze data in the form of tables, charts and graphs. They are mainly used for budgeting and inventory management because they offer powerful tools for financial analysis and data organization. With a spreadsheet package, you can create and format tables with columns and rows to track expenses, sales, and other important data. You can also use formulas and functions to automatically calculate totals, averages, and other important metrics. In addition to budgeting and inventory, spreadsheet packages can also be used for a wide range of other tasks, such as analyzing data trends, creating charts and graphs to visualize data, and performing mathematical calculations. Some spreadsheet packages even offer features for collaborating on documents and sharing data with others in real-time. However, spreadsheet packages are not designed for database management, word processing, drawing, or painting. For those tasks, you would need to use other software programs designed specifically for those purposes.

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The map of Nigeria is an example of graphic data. Graphic data refers to any visual representation of information or data, such as graphs, charts, diagrams, and maps. In this case, the map of Nigeria is a visual representation of the geographic features and boundaries of the country. It shows the different regions, states, and cities within Nigeria, as well as its neighboring countries and bodies of water. The map uses a combination of colors, symbols, and labels to convey information about Nigeria's geography in a clear and easily understandable way.

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The three major types of language translators are: Assembler, Compiler, and Interpreter. An Assembler is a translator that converts assembly language code, which is a low-level programming language, into machine language code that a computer can understand and execute. Assembly language is specific to a particular computer architecture, so an assembler is also specific to that architecture. A Compiler is a translator that converts high-level programming language code, which is more human-readable, into machine language code that a computer can understand and execute. The process of compilation involves several stages, including lexical analysis, syntax analysis, semantic analysis, code generation, and optimization. Once compiled, the resulting machine code can be run repeatedly without needing to recompile the source code. An Interpreter is a translator that works by executing high-level programming language code directly, without the need to first compile it into machine language code. Interpreters translate code line-by-line, executing each line immediately before moving on to the next one. This process is slower than compilation, but it allows for greater flexibility and interactivity during development, as changes to the source code can be tested immediately without needing to recompile.

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The answer is "close symbol." Flowcharts are diagrams that are used to represent the flow of a process or system. They use different symbols to represent different elements of the process, such as starting points, decision points, and actions. Terminal symbols, also known as start/end symbols, are used to indicate the beginning or end of a process or flowchart. Process symbols are used to represent actions or steps in the process, while input/output symbols are used to represent data inputs or outputs. However, there is no such thing as a "close symbol" in flowcharting. There are, however, symbols such as the decision symbol, which is used to indicate a point in the process where a decision needs to be made based on a condition or set of conditions. In summary, the correct answer is "close symbol" because there is no such symbol used in flowcharting.

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The suite of software that controls and manages the basic operation of a computer is called system software. It includes programs that provide essential functionalities like managing hardware resources, running other software applications, and providing a user interface for interacting with the computer. Examples of system software include operating systems like Windows, macOS, and Linux, device drivers, system utilities, and firmware. System software is different from application software, which is designed to perform specific tasks like word processing, spreadsheet management, or video editing.

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Data that is copied from an application is stored in the clipboard. The clipboard is a temporary storage location that allows you to copy and paste information between different applications or within the same application. When you copy data, it is stored in the clipboard, which is a type of memory that holds the data until you paste it elsewhere. Once you paste the data, it is removed from the clipboard, and the clipboard is ready to store new data. Therefore, the clipboard acts as a buffer that allows you to move information from one place to another, making it a useful tool for working with multiple applications or files.

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Data transfer cannot be initiated through trunking pipe. Trunking pipes are used to protect and route cables, but they are not capable of initiating data transfer themselves. On the other hand, coaxial cable, fibre cable, and twisted pair cable are all examples of media that can be used to initiate data transfer. Coaxial cable uses a central conductor surrounded by insulation and a grounded shield to transmit signals, while fibre cable uses thin strands of glass or plastic to transmit light signals, and twisted pair cable uses pairs of copper wires twisted together to transmit electrical signals. Each of these media has its own advantages and disadvantages, and the choice of which one to use will depend on factors such as distance, bandwidth requirements, and cost.

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To hold row and column titles in place so that they do not scroll when the user scrolls a worksheet in Microsoft Excel, you can use the Freeze Panes command on the Windows menu. This command allows you to select a row or column that you want to keep in place, and then freeze that row or column so that it remains visible when you scroll through the rest of the worksheet. This feature is helpful when you have a large spreadsheet with many rows and columns, and you want to keep the headers or labels in view as you work with the data. The other options listed in the question (Hold Titles, Split, and Show Grid) do not have the same function as Freeze Panes and will not allow you to hold row and column titles in place.

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A NAND gate is a logic gate that produces an output of 0 only when all its inputs are 1. In all other cases, the output is 1. So, if any of the inputs is 0, the output will be 1. If all the inputs are 1, the output will be 0. To put it another way, the NAND gate behaves like an "inverted AND" gate. It produces an output of 1 when any of the inputs is 0, and only produces an output of 0 when all the inputs are 1. This behavior makes the NAND gate a very useful building block in digital circuits, as it can be used to implement any other logical function.

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The two kinds of sound effect files that can be added to a presentation in Microsoft PowerPoint are .wav files and .mid files. .wav files are audio files that contain sound recordings, such as music or voice recordings. They are widely used for sound effects and background music in presentations. .mid files are musical instrument digital interface files that contain musical notes and instructions for playing them. They are used to add background music or sound effects to a presentation that are specifically composed or synthesized for the presentation.

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The cell that contains the pointer or cursor in Microsoft Excel is referred to as the "Active Cell". An active cell is the cell that is selected and ready to accept data or a formula. You can tell which cell is active because its border is highlighted with a different color or pattern. When you start typing, the data will be entered into the active cell.

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Machine language instructions are expressed in binary. Binary is a system of representing numbers using only two digits, 0 and 1. Computers understand and process data in binary form, making it the most basic and fundamental language for computers. Machine language instructions are written using binary code, which the computer can directly execute without any further translation.

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The labeling of hard drives depends on the specific operating system being used. However, it is common for disk operating systems to label hard drives as letters starting from "C". This is because the first two letters, "A" and "B", are reserved for floppy drives. So, the most common labeling of hard drives is "C, D, and E".

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The true statements about a computer are: I. Constructed from electronic components: A computer is an electronic device that is constructed using various electronic components such as transistors, capacitors, resistors, etc. III. It has facility for storage of data and programs: A computer has a storage device, such as a hard disk, that allows it to store data and programs for later use. IV. It has provision for input and output of data: A computer has various input devices such as a keyboard and mouse, which allow users to input data, and output devices such as a monitor or printer, which allow users to receive information from the computer. II. It has self-regeneration capability: This statement is not true. While computers are designed to detect and correct errors, they do not have the ability to regenerate or repair themselves without human intervention. Therefore, the statements that are true about computers are I, III, and IV.

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The set of instructions written by computer experts to solve a specific task of the user is called application software. Application software is a type of computer software that is designed to perform specific tasks, such as word processing, spreadsheet management, and media editing. It is created by developers to meet the needs of users, and it is installed onto a computer to help the user perform a certain task. Examples of application software include Microsoft Word, Excel, and Adobe Photoshop. Operating systems, system software, and utility software are different types of software. The operating system is the primary software that manages all of the hardware and software resources of a computer, while system software includes programs that help manage and maintain the computer, such as device drivers, security software, and system utilities. Utility software refers to programs that are designed to perform specific tasks, such as disk cleanup, backup, and optimization.

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The file organization method that can be accessed both randomly and sequentially is the Indexed Sequential Files. Indexed Sequential Files use an index to organize data records, allowing for both sequential and random access. The records are stored in sequence based on a primary key field, and the index keeps track of the location of each record. This allows for sequential access by reading the records in order, or random access by searching for a specific record based on its key value. For example, imagine a library catalog that is organized using an Indexed Sequential File. The books in the library are stored in order by their call numbers (i.e., the primary key field), and an index is kept that maps each call number to its location in the library. A patron could browse the catalog sequentially by looking at each book in order, or they could search for a specific book by using the index to find its location. Overall, Indexed Sequential Files provide the flexibility of both sequential and random access, making them a popular choice for applications that require both types of access.

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The collection of software that allows a computer to operate is called an Operating System (OS). An Operating System is a software that manages computer hardware and provides common services for computer programs. It acts as an interface between the hardware components of the computer and the applications that run on it. The operating system is responsible for managing resources such as memory, CPU time, and input/output operations. It also provides a user interface that enables users to interact with the computer and run applications. General-purpose software and specific software are not appropriate terms to describe the collection of software that allows a computer to operate. General-purpose software refers to software that can perform a variety of functions, such as word processing, spreadsheet management, and email communication. Specific software, on the other hand, is designed to perform a particular task, such as graphic design or accounting. Utility software, on the other hand, refers to software that performs specific tasks to maintain the performance and functionality of a computer system, such as virus scanners, disk defragmenters, and backup tools. However, utility software alone cannot allow a computer to operate; it needs an operating system to function. Therefore, the collection of software that allows a computer to operate is called an Operating System.

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Modern computers are faster and smaller compared to earlier computers. They can perform many tasks much faster and have more storage capacity for things like music, videos, and photos. They also often come in compact designs that make them more portable. However, it is important to note that technology is constantly evolving, so it's possible for there to be newer computers that are even faster and smaller than current ones.

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(a) Four ways a music (data) file can be organised on a storage medium:

1. Serial organisation: records are stored one after another in the order in which they are created, with no particular key sequence.
2. Sequential organisation: records are stored in a sorted order based on a key field (for example, by track number or title), so they can be read in that order.
3. Random (direct) organisation: each record is placed at a storage address calculated from its key, allowing any record to be accessed directly without reading the ones before it.
4. Indexed (index-sequential) organisation: records are stored in sequence but an index is also kept, so a record can be found either directly through the index or by reading in sequence.

(b) Two basic operations on a computer file:

• Reading (retrieving/opening) data from the file.
• Writing (saving/storing) data into the file.

Other acceptable operations: create, open, close, update/edit, delete, append, sort, search.

(c) Explanation of terms:

(i) File: A file is a collection of related records stored together under one name on a storage medium and treated as a single unit. For example, a file may hold all the records of a musician's songs.

(ii) Record: A record is a collection of related fields that describe one item or entity within a file. For example, in a music file a single record may hold the title, artist, duration and file size of one song.

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(a)(i) Encryption is the process of converting readable data (plaintext) into a coded, unreadable form (ciphertext) using an algorithm and a key, so that only an authorised person holding the correct key can decode (decrypt) and read it. Its purpose is to protect the confidentiality of data during storage or transmission.

(a)(ii) Authentication techniques (tick two): Of the four items listed, only Biometric and Password are used to verify a user's identity. A firewall is a network-protection barrier and an intranet is a private network; neither authenticates a user.

(a)(iii) Two features of data encryption:

• It uses a key together with an algorithm to scramble the data, and the same or a matching key is required to reverse it.
• The encrypted output (ciphertext) is unintelligible to anyone who intercepts it without the key, so it preserves confidentiality and integrity of the message.

(b) Four factors that may cause delay in transferring data between mobile phones:

1. Weak or unstable network / signal strength between the two devices (poor Bluetooth or Wi-Fi connection).
2. Large file size of the data being exchanged, which takes longer to send.
3. Low available bandwidth or transfer speed of the connection technology being used.
4. Distance or obstacles between the phones, or interference from other electronic/radio devices.

(Other acceptable factors: low battery power forcing power-saving mode, a slow or busy processor, or too many applications running in the background.)

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(a)(i) What is a firewall?

A firewall is a hardware device, software program, or a combination of both that monitors and controls the flow of data (network traffic) between a computer or private network and an external network such as the Internet. It works by examining incoming and outgoing packets against a set of security rules, allowing safe traffic to pass while blocking unauthorised or malicious traffic. In this way it acts as a protective barrier that prevents intruders and harmful data from reaching the protected system.

(a)(ii) Two methods used in protecting the computer system:

• Installing and updating anti-virus software to detect, quarantine and remove malicious programs.
• Using passwords and user authentication (strong passwords, PINs or biometrics) to restrict access to authorised users only.

Other acceptable methods: using a firewall, regular data backup, encryption of data, keeping the operating system patched/updated, physically securing the hardware.

(b) Stages of the System Development Life Cycle (SDLC):

(i) Feasibility study: This is the early investigation stage that examines whether the proposed system is worth developing. The analyst studies the existing system and assesses the project in terms of technical feasibility (can it be built with available technology?), economic feasibility (do the benefits justify the cost?), and operational feasibility (will users accept and use it?). The result is a feasibility report that recommends whether the project should proceed.

(ii) Design: At this stage the requirements gathered in earlier phases are translated into a detailed plan for the new system. The designer specifies the inputs, outputs, processes, user interfaces (screens and reports), file and database structures, and the hardware and software needed. Both the logical design (what the system will do) and the physical design (how it will be built) are produced as a blueprint for the programmers.

(iii) Maintenance: This is the ongoing stage after the system has been installed and is in use. It involves correcting errors (bugs) discovered during operation, adapting the system to changes in the environment or organisation, and improving or upgrading it to meet new requirements. Maintenance keeps the system accurate, reliable and useful throughout its working life.

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(a) Explanation of terms:

(i) Storage device: A storage device is a piece of computer hardware used to record (write) and hold (retain) data, instructions and information either temporarily or permanently, so that they can be retrieved (read) later. Examples include the hard disk, flash drive, memory card and optical (CD/DVD) disk.

(ii) Virtual memory: Virtual memory is a memory-management technique in which a portion of the hard disk (secondary storage) is set aside and used as an extension of the main memory (RAM). When the RAM becomes full, the operating system temporarily moves some data or program pages to this disk area, giving the impression that the computer has more RAM than it physically has. This allows large programs to run even when physical RAM is limited.

(b) Calculations

(i) Number of bits held by each device

Recall: \(1\text{ byte} = 8\text{ bits}\), \(1\text{ KB} = 1024\text{ bytes}\), \(1\text{ MB} = 1024\text{ KB} = 1024 \times 1024\text{ bytes}\).

2 KB:

\[2\text{ KB} = 2 \times 1024\text{ bytes} = 2048\text{ bytes}\]

\[= 2048 \times 8\text{ bits} = 16384\text{ bits}\]

2 MB:

\[2\text{ MB} = 2 \times 1024 \times 1024\text{ bytes} = 2097152\text{ bytes}\]

\[= 2097152 \times 8\text{ bits} = 16777216\text{ bits}\]

(ii) Total capacity of the two devices together, in bytes

\[2\text{ KB} = 2048\text{ bytes}\]

\[2\text{ MB} = 2097152\text{ bytes}\]

\[\text{Total} = 2048 + 2097152 = 2099200\text{ bytes}\]

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(a)

i)Flow chart diagram

ii) Name the parts

(b)

1. (i) The documentation stage in Program Development Life Cycle is the stage where the developer writes down the details of the program including its design, code, and testing procedures. This documentation helps in maintaining and updating the program later.
2. (ii) Three characteristics of a good computer program are:
• 1. User-friendly: The program should be easy to use and understand for the intended audience.
• 2. Efficient: The program should run quickly and efficiently, without taking up too much memory or processing power.
• 3. Reliable: The program should produce accurate and reliable results and should be free of bugs and errors.