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1

Xia has three files stored on her computer. Tick (3) one box to show which is the largest file size. File size Tick (✔) 999 kB 1 MB 850 000 bytes Denise has three files stored on her computer. Tick (3) one box to show which is the smallest file size. File size Tick (✔) 4000 MB 2 GB 2 500 000 kB

1. Data representation  →  1.3. Data storage and compression

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2

A sports stadium has an electronic counter that counts each person that enters the stadium. The count is stored as binary in a 16-bit register. A denary value of the count is displayed on a screen at the entrance. The screen currently displays: 0 0 7 1 Give the binary value that is stored in the register to display the count shown. Binary value: Working space More people enter the sports stadium and the screen now displays: 0 2 5 7 Give the binary value that is stored in the register to display the count shown. Binary value: Working space After everyone has entered the stadium, the register stores the binary value: Show what the screen will display when this binary value is stored. Display: Working space Sensors are used at the entrance to count the number of people entering the stadium. Identify two sensors that could be used to count the number of people entering the stadium. Sensor 1 Sensor 2 Tick (3) one box to show if a sensor is an example of an input device, storage device or output device. Device Tick (✔) input storage output

1. Data representation  →  1.1. Number systems

3. Hardware  →  3.2. Input and output devices

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3

Five statements are given about error-checking methods. Tick (3) to show whether each statement applies to Automatic Repeat reQuest (ARQ), check digit or checksum. Some statements may apply to more than one error-checking method. Statement ARQ (✔) Check digit (✔) Checksum (✔) checks for errors on data entry uses a process of acknowledgement and timeout compares two calculated values to see if an error has occurred may resend data until it is confirmed as received checks for errors in data after transmission from a computer to another Identify one other error-checking method.

2. Data transmission  →  2.2. Methods of error detection

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4

Frederick prints a document that he has typed. The printer begins to print the document, but then a message is displayed on Frederick’s computer to say that the paper has jammed. Describe the role of an interrupt in generating a message on the computer that the paper has jammed. Give two other examples of when an interrupt signal could be generated. The type of data transmission between the computer and the printer is serial half-duplex data transmission. Describe how data is transmitted using serial half-duplex data transmission. Explain why the data transmission needs to be half-duplex rather than simplex.

4. Software  →  4.1. Types of software and interrupts

2. Data transmission  →  2.1. Types and methods of data transmission

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5

In a Von Neumann model for a computer system, a Central Processing Unit (CPU) contains a number of different components. The table contains the name of a component or a description of their role in the fetch-execute cycle. Complete the table with the missing component names and descriptions. Component name Description Memory Address Register (MAR) Program Counter (PC) This is a register that is built into the arithmetic logic unit. It temporarily holds the result of a calculation. This is a register that holds data or an instruction that has been fetched from memory. Control Unit (CU) This carries addresses around the CPU.

3. Hardware  →  3.1. Computer architecture

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6

The paragraph describes an MP3 file, MP4 file and a MIDI file. Complete the paragraph using the list of terms. Not all terms in the list need to be used. • can • cannot • compressed • image • microphone • MIDI • MP3 • MP4 • notes • pixels • speaker • should • uncompressed files are a multimedia format that stores video and audio. files are only used as a digital recording of sound; they are created using a and recording software. The data in the file is . files contain instructions on how to create the sound. They are created using digital instruments. The file stores individual , each one be changed in this type of file.

1. Data representation  →  1.3. Data storage and compression

8. Programming  →  8.3. File handling

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7

Julius creates a computer application that calculates how many years it will take to pay for a house. Julius uploads his application to his website for people to download. Before he uploads the application, he translates the code using a compiler. Explain why Julius uses a compiler, rather than an interpreter, to do this. Julius also creates videos to explain how to use the application that he has created. He reduces the file size of the videos using lossless compression. Describe how lossless compression reduces the file size of the video. State why Julius uses lossless compression, rather than lossy compression. Julius wants to distribute his application to a wider audience. He is considering distributing it as freeware or free software. Describe freeware and free software. Freeware Free software Julius also considers distributing a trial version of the application. Identify the type of software he could use to distribute his application as a trial version. Julius makes sure that all data transmission to and from his website is secure. One way a user can check if his website uses secure data transmission is to check its certificate. Give two other ways that a user can identify if his website uses secure data transmission.

1. Data representation  →  1.3. Data storage and compression

4. Software  →  4.1. Types of software and interrupts

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8

Consider the following logic statement: X = (((A OR B) AND (NOT(B XOR C))) OR NOT C) Draw a logic circuit to represent the given logic statement. Do not attempt to simplify the logic statement. All logic gates must have a maximum of two inputs. A B X C Complete the truth table for the given logic statement. A B C Working space X

10. Boolean logic  →  10. Boolean logic

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9

A parity check is used to check for errors after transmission on the four given binary values. All four values are transmitted and received correctly. Identify whether each 8-bit binary value has been sent using odd or even parity by writing odd or even in the type of parity column. Binary value Type of parity

2. Data transmission  →  2.2. Methods of error detection

1. Data representation  →  1.1. Number systems

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10

A denial of service (DoS) attack is a type of Internet security risk. State the purpose of a denial of service attack. Phishing and pharming are also types of Internet security risk. They have the same purpose. State the purpose of phishing and pharming. Identify three other types of Internet security risk.

5. The internet and its uses  →  5.3. Cyber security

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