WAEC SSCE - Computer Studies - 2017 (Essay)
Question 1 Rapport
(a) Convert 1011011\(_2\) to its hexadecimal equivalent
(b) State one difference a hacker and a scammer
(c) identify the parts labeled A, B, C and D on the keyboard shown below
(a) Convert \(1011011_2\) to hexadecimal
Method 1 (through denary):
\[1011011_2 = (1\times2^6)+(0\times2^5)+(1\times2^4)+(1\times2^3)+(0\times2^2)+(1\times2^1)+(1\times2^0)\]
\[= 64+0+16+8+0+2+1 = 91_{10}\]
Dividing 91 repeatedly by 16: \(91 = 5\times16 + 11\), where \(11 = \text{B}\). Reading the digits gives \(5\text{B}\).
Method 2 (direct grouping): group the bits in fours from the right, \(0101\;1011\). Then \(0101 = 5\) and \(1011 = \text{B}\).
Therefore \(1011011_2 = 5\text{B}_{16}\).
(b) One difference between a hacker and a scammer
A hacker is a person who uses backend technical knowledge of software to gain unauthorised access to the computer systems or accounts of unsuspecting users, with the aim of stealing, altering or exploiting data. A scammer deceives victims through confidence tricks, sending unwanted or inappropriate electronic messages to many recipients, or luring the victim into granting remote access, in order to defraud them. In short, the hacker breaks in through technical means, while the scammer relies on deception to make the victim hand over money or information.
(c) Parts labelled A, B, C and D on the keyboard
- A - Function keys (F1 to F12), the row along the top.
- B - Alphanumeric (typing) keys, the central QWERTY block of letters, numbers and symbols.
- C - Numeric keypad, the calculator-style block of number keys on the right.
- D - Cursor (arrow) control keys, used to move the pointer up, down, left and right.
Détails de la réponse
(a) Convert \(1011011_2\) to hexadecimal
Method 1 (through denary):
\[1011011_2 = (1\times2^6)+(0\times2^5)+(1\times2^4)+(1\times2^3)+(0\times2^2)+(1\times2^1)+(1\times2^0)\]
\[= 64+0+16+8+0+2+1 = 91_{10}\]
Dividing 91 repeatedly by 16: \(91 = 5\times16 + 11\), where \(11 = \text{B}\). Reading the digits gives \(5\text{B}\).
Method 2 (direct grouping): group the bits in fours from the right, \(0101\;1011\). Then \(0101 = 5\) and \(1011 = \text{B}\).
Therefore \(1011011_2 = 5\text{B}_{16}\).
(b) One difference between a hacker and a scammer
A hacker is a person who uses backend technical knowledge of software to gain unauthorised access to the computer systems or accounts of unsuspecting users, with the aim of stealing, altering or exploiting data. A scammer deceives victims through confidence tricks, sending unwanted or inappropriate electronic messages to many recipients, or luring the victim into granting remote access, in order to defraud them. In short, the hacker breaks in through technical means, while the scammer relies on deception to make the victim hand over money or information.
(c) Parts labelled A, B, C and D on the keyboard
- A - Function keys (F1 to F12), the row along the top.
- B - Alphanumeric (typing) keys, the central QWERTY block of letters, numbers and symbols.
- C - Numeric keypad, the calculator-style block of number keys on the right.
- D - Cursor (arrow) control keys, used to move the pointer up, down, left and right.
Question 2 Rapport
(a) What are input devices?
(b) list two input devices
(c) State two uses of logic gates
(d) Draw and label the logic gate symbol for;
(i) OR gate (ii) AND gate
(a) What are input devices?
Input devices are hardware devices (peripherals) connected to a computer that are used to enter data, instructions, commands or signals into the computer system for processing. They allow the user to interact with and control the computer.
(b) Two input devices
- Keyboard
- Mouse
(Scanner, joystick, microphone, light pen, webcam, barcode reader and fingerprint scanner are also acceptable.)
(c) Two uses of logic gates
- They serve as the building blocks of digital electronic circuits, used to construct the Arithmetic and Logic Unit (ALU), adders and memory cells inside the processor.
- They are used as decision-making elements in control circuits such as burglar alarms, traffic-light controllers and automatic push-button lock circuits.
(d) Logic gate symbols
(i) OR gate – the output is 1 when at least one of the inputs A or B is 1.
(ii) AND gate – the output is 1 only when both inputs A and B are 1.
Détails de la réponse
(a) What are input devices?
Input devices are hardware devices (peripherals) connected to a computer that are used to enter data, instructions, commands or signals into the computer system for processing. They allow the user to interact with and control the computer.
(b) Two input devices
- Keyboard
- Mouse
(Scanner, joystick, microphone, light pen, webcam, barcode reader and fingerprint scanner are also acceptable.)
(c) Two uses of logic gates
- They serve as the building blocks of digital electronic circuits, used to construct the Arithmetic and Logic Unit (ALU), adders and memory cells inside the processor.
- They are used as decision-making elements in control circuits such as burglar alarms, traffic-light controllers and automatic push-button lock circuits.
(d) Logic gate symbols
(i) OR gate – the output is 1 when at least one of the inputs A or B is 1.
(ii) AND gate – the output is 1 only when both inputs A and B are 1.
Question 3 Rapport
State one difference between star and bus topologies
(b) List four common network devices.
(c) Write the acronyms below in full
HTML, HTTP, ISP, SMTP.
(a) One difference between star and bus topologies
In a star topology every computer is connected by its own cable to a central device (a hub or switch), so all data passes through that central point; if one cable fails only that one computer is affected. In a bus topology all computers are connected to a single common cable (the backbone), and if that main cable breaks the whole network goes down.
(b) Four common network devices
- Hub.
- Switch.
- Router.
- Modem. (Network interface card, bridge and repeater are also acceptable.)
(c) The acronyms in full
- HTML - HyperText Markup Language
- HTTP - HyperText Transfer Protocol
- ISP - Internet Service Provider
- SMTP - Simple Mail Transfer Protocol
Détails de la réponse
(a) One difference between star and bus topologies
In a star topology every computer is connected by its own cable to a central device (a hub or switch), so all data passes through that central point; if one cable fails only that one computer is affected. In a bus topology all computers are connected to a single common cable (the backbone), and if that main cable breaks the whole network goes down.
(b) Four common network devices
- Hub.
- Switch.
- Router.
- Modem. (Network interface card, bridge and repeater are also acceptable.)
(c) The acronyms in full
- HTML - HyperText Markup Language
- HTTP - HyperText Transfer Protocol
- ISP - Internet Service Provider
- SMTP - Simple Mail Transfer Protocol
Question 4 Rapport
(a) Convert 1011011\(_2\) to its hexadecimal equivalent
(b) State one difference a hacker and a scammer
(c) identify the parts labeled A, B, C and D on the keyboard shown below
(a) Convert \(1011011_2\) to hexadecimal
Method 1 (through denary):
\[1011011_2 = (1\times2^6)+(0\times2^5)+(1\times2^4)+(1\times2^3)+(0\times2^2)+(1\times2^1)+(1\times2^0)\]
\[= 64+0+16+8+0+2+1 = 91_{10}\]
Dividing 91 repeatedly by 16: \(91 = 5\times16 + 11\), where \(11 = \text{B}\). Reading the digits gives \(5\text{B}\).
Method 2 (direct grouping): group the bits in fours from the right, \(0101\;1011\). Then \(0101 = 5\) and \(1011 = \text{B}\).
Therefore \(1011011_2 = 5\text{B}_{16}\).
(b) One difference between a hacker and a scammer
A hacker is a person who uses backend technical knowledge of software to gain unauthorised access to the computer systems or accounts of unsuspecting users, with the aim of stealing, altering or exploiting data. A scammer deceives victims through confidence tricks, sending unwanted or inappropriate electronic messages to many recipients, or luring the victim into granting remote access, in order to defraud them. In short, the hacker breaks in through technical means, while the scammer relies on deception to make the victim hand over money or information.
(c) Parts labelled A, B, C and D on the keyboard
- A - Function keys (F1 to F12), the row along the top.
- B - Alphanumeric (typing) keys, the central QWERTY block of letters, numbers and symbols.
- C - Numeric keypad, the calculator-style block of number keys on the right.
- D - Cursor (arrow) control keys, used to move the pointer up, down, left and right.
Détails de la réponse
(a) Convert \(1011011_2\) to hexadecimal
Method 1 (through denary):
\[1011011_2 = (1\times2^6)+(0\times2^5)+(1\times2^4)+(1\times2^3)+(0\times2^2)+(1\times2^1)+(1\times2^0)\]
\[= 64+0+16+8+0+2+1 = 91_{10}\]
Dividing 91 repeatedly by 16: \(91 = 5\times16 + 11\), where \(11 = \text{B}\). Reading the digits gives \(5\text{B}\).
Method 2 (direct grouping): group the bits in fours from the right, \(0101\;1011\). Then \(0101 = 5\) and \(1011 = \text{B}\).
Therefore \(1011011_2 = 5\text{B}_{16}\).
(b) One difference between a hacker and a scammer
A hacker is a person who uses backend technical knowledge of software to gain unauthorised access to the computer systems or accounts of unsuspecting users, with the aim of stealing, altering or exploiting data. A scammer deceives victims through confidence tricks, sending unwanted or inappropriate electronic messages to many recipients, or luring the victim into granting remote access, in order to defraud them. In short, the hacker breaks in through technical means, while the scammer relies on deception to make the victim hand over money or information.
(c) Parts labelled A, B, C and D on the keyboard
- A - Function keys (F1 to F12), the row along the top.
- B - Alphanumeric (typing) keys, the central QWERTY block of letters, numbers and symbols.
- C - Numeric keypad, the calculator-style block of number keys on the right.
- D - Cursor (arrow) control keys, used to move the pointer up, down, left and right.
Question 5 Rapport
(a) In a tabular form, state two differences between random access memory and read only memory
(b) State four characteristics of windows operating system environment.
(c) list two examples of utility programs
(a) Two differences between RAM and ROM
| Random Access Memory (RAM) | Read Only Memory (ROM) |
|---|---|
| It is volatile - its contents are lost when the power is switched off. | It is non-volatile - its contents are retained when the power is switched off. |
| Data can be both read from and written to it by the user. | Its contents are normally read only and are written in by the manufacturer. |
(b) Four characteristics of the Windows operating system environment
- It has a Graphical User Interface (GUI) with icons, menus and windows.
- It is multi-tasking - it can run several programs at the same time.
- It is mainly mouse (pointer) driven, with point-and-click and drag-and-drop operations.
- It uses a desktop with a taskbar and Start menu, and supports plug-and-play devices. (WYSIWYG display is also acceptable.)
(c) Two examples of utility programs
- Antivirus program.
- Disk defragmenter (or a file-compression / backup program).
Détails de la réponse
(a) Two differences between RAM and ROM
| Random Access Memory (RAM) | Read Only Memory (ROM) |
|---|---|
| It is volatile - its contents are lost when the power is switched off. | It is non-volatile - its contents are retained when the power is switched off. |
| Data can be both read from and written to it by the user. | Its contents are normally read only and are written in by the manufacturer. |
(b) Four characteristics of the Windows operating system environment
- It has a Graphical User Interface (GUI) with icons, menus and windows.
- It is multi-tasking - it can run several programs at the same time.
- It is mainly mouse (pointer) driven, with point-and-click and drag-and-drop operations.
- It uses a desktop with a taskbar and Start menu, and supports plug-and-play devices. (WYSIWYG display is also acceptable.)
(c) Two examples of utility programs
- Antivirus program.
- Disk defragmenter (or a file-compression / backup program).
Question 6 Rapport
(a) Match each of the following computing devices.
| COMPUTER DEVICES | USES |
| EDVAC | Electronic general-purpose computer programmed to perform complex sequences of operation. |
| ENIAC | Electronic digital stored-program computer intended for the bureau of census and later for presidential election. |
| UNIVAC | Electronic computer, binary in nature with automatic addition, subtraction multiplication and programmed division. |
The three descriptions in the question have been shuffled. Each early electronic computer is matched to the description that historically belongs to it.
Reasoning:
- ENIAC (Electronic Numerical Integrator and Computer, 1945) was the first large-scale, electronic, general-purpose machine. It was reprogrammed by rewiring to carry out long, complex sequences of operations.
- EDVAC (Electronic Discrete Variable Automatic Computer, 1949) was the first widely known machine designed to work in binary, and it performed automatic addition, subtraction, multiplication and programmed division.
- UNIVAC (Universal Automatic Computer, 1951) was an electronic digital stored-program computer built for the U.S. Bureau of the Census, and later famous for predicting a presidential election result.
| Computer device | Correct use / description |
|---|---|
| EDVAC | Electronic computer, binary in nature, with automatic addition, subtraction, multiplication and programmed division. |
| ENIAC | Electronic general-purpose computer programmed to perform complex sequences of operations. |
| UNIVAC | Electronic digital stored-program computer intended for the Bureau of the Census and later for a presidential election. |
Détails de la réponse
The three descriptions in the question have been shuffled. Each early electronic computer is matched to the description that historically belongs to it.
Reasoning:
- ENIAC (Electronic Numerical Integrator and Computer, 1945) was the first large-scale, electronic, general-purpose machine. It was reprogrammed by rewiring to carry out long, complex sequences of operations.
- EDVAC (Electronic Discrete Variable Automatic Computer, 1949) was the first widely known machine designed to work in binary, and it performed automatic addition, subtraction, multiplication and programmed division.
- UNIVAC (Universal Automatic Computer, 1951) was an electronic digital stored-program computer built for the U.S. Bureau of the Census, and later famous for predicting a presidential election result.
| Computer device | Correct use / description |
|---|---|
| EDVAC | Electronic computer, binary in nature, with automatic addition, subtraction, multiplication and programmed division. |
| ENIAC | Electronic general-purpose computer programmed to perform complex sequences of operations. |
| UNIVAC | Electronic digital stored-program computer intended for the Bureau of the Census and later for a presidential election. |
