| Date | November 2019 | Marks available | 1 | Reference code | 19N.1.SL.TZ0.4 |
| Level | SL | Paper | 1 | Time zone | no time zone |
| Command term | State | Question number | 4 | Adapted from | N/A |
Question
Colours are represented by a computer as a combination of the three primary colours: red, green and blue.
Numerical values are used to represent the different shades of each primary colour. These values range from 0 to 255 in decimal, or 00 to FF in hexadecimal.
State why hexadecimal numbers are frequently used in computing.
State the number of bits used to represent a non-primary colour, such as yellow.
State the maximum number of colours that can be represented in a computer pixel.
Markscheme
Award [1 max].
Hexadecimal numbers are used for shorter representation of data because a (modern) byte can be represented exactly by two hexadecimal digits;
Hexadecimal numbers are used for shorter representation of data, because computers store and handle binary digits, and four binary digits make one hexadecimal digit;
Award [1 max].
24;
Award [1 max].
256 × 256 × 256 / (28)3 / 224;
2563;
16 777 216;
Examiners report
This question required candidates to recognise that hexadecimal numbers are used for shorter representation of equivalent binary numbers, and the relationship between groups of binary digits and individual hexadecimal digits. Answers seen, were often too vague, simply stating that, for example, the numbers are easier to use.
This question required candidates to realise that non-primary colours are stored as a combination of the three primary colours red, green and blue. 8 bits are required for each of these, making 24 bits necessary to store each non-primary colour. Many answers seen incorrectly gave 8 bits as the requirement.
As with part b, candidates were expected to recognise that each computer pixel would be made up from a combination of each of the three primary colours, with one byte, 8 bits, or 28 = 256 combinations for each primary colour. The answer would therefore be 256 × 256 × 256, or 16 777 216 combinations. Many answers seen incorrectly gave 256 combinations.
Syllabus sections
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18M.1.SL.TZ0.3:
Calculate how many different colours can be represented using two hexadecimal characters.
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21N.1.HL.TZ0.2:
State the hexadecimal representation of the binary number 10001010.
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22M.1.SL.TZ0.8:
Identify one function of a single-user operating system.
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22M.1.SL.TZ0.6:
Draw the truth table for the following logic circuit.
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22M.1.SL.TZ0.7a:
Calculate, showing your working in each case: the binary (base 2) value of the denary (base 10) number: 105.
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22M.1.SL.TZ0.9:
Define the term usability.
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22M.1.SL.TZ0.11:
Explain how cache memory affects system performance.
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21M.1.SL.TZ0.3:
Draw the logic circuit represented by the following truth table.
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22M.1.SL.TZ0.7b:
Calculate, showing your working in each case: the hexadecimal (base 16) value of the denary (base 10) number: 200.
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17N.1.SL.TZ0.5:
Copy and complete the following truth table.
- 17N.1.SL.TZ0.8a: State where all instructions and data are stored.
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17N.1.SL.TZ0.11b:
State one advantage of this feature.
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19M.1.SL.TZ0.15c:
Identify two types of general application software that would be installed on the training computers.
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18N.1.SL.TZ0.4:
Construct a logic diagram for the following expression.
NOT A OR (A AND B)
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18N.1.SL.TZ0.8c.i:
State how the data stored in the byte will be represented in hexadecimal.
- 19M.1.SL.TZ0.5: State the hexadecimal equivalent of the following binary number: 11011111
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19M.1.SL.TZ0.6:
Construct the truth table from the following logic circuit.
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18M.1.SL.TZ0.2:
Outline the role of the memory data register in the machine execution cycle.
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17N.1.HL.TZ0.10a:
Describe how a spellchecker checks whether a word in a text file is correctly spelt or not.
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19M.1.SL.TZ0.8:
State the part of the central processing unit (CPU) that is responsible for carrying out calculations.
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19M.1.SL.TZ0.2:
Identify two features of a graphical user interface (GUI).
- 19M.1.SL.TZ0.15b: State the purpose of persistent storage on the computers.
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18M.1.SL.TZ0.4:
Explain the importance of the memory management function of an operating system.
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18M.1.SL.TZ0.5:
Construct a logic diagram for the following Boolean expression.
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21M.1.SL.TZ0.5:
Calculate the denary (base 10) equivalent of the hexadecimal number BF.
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17N.1.SL.TZ0.11a:
Describe how a spellchecker checks whether a word in a text file is correctly spelt or not.
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17N.1.SL.TZ0.11c:
Identify two additional features of a word processing package that could be useful for this office.
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18N.1.SL.TZ0.2a:
Outline what is meant by a database management system.
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18N.1.SL.TZ0.8a.ii:
Outline the function of an operating system in managing primary memory.
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18N.1.SL.TZ0.8c.ii:
State how many integers could be represented in this byte.
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18N.1.SL.TZ0.8d:
Construct a truth table with two input variables. If the input variables are equal the value of the output variable should be True, otherwise it should be False.
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19N.1.SL.TZ0.4b:
State the number of bits used to represent a non-primary colour, such as yellow.
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19M.1.SL.TZ0.15a:
Identify two characteristics of RAM.
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20N.1.SL.TZ0.4c:
Outline the function of the memory address register (MAR).
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19M.1.SL.TZ0.7:
Outline the purpose of the memory address register (MAR) in the central processing unit (CPU).
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21M.1.SL.TZ0.11:
Construct the truth table for the following logic circuit:
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18N.1.SL.TZ0.8a.i:
Distinguish between random access memory (RAM) and read only memory (ROM).
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17N.1.SL.TZ0.8b:
Outline the role of the data bus and address bus in this process.
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19N.1.SL.TZ0.3b:
Explain the purpose of cache memory.
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18N.1.SL.TZ0.8c.iii:
Outline why this byte could not be used to represent characters such as those used in Chinese.
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20N.1.SL.TZ0.8c.ii:
Explain how the operating system ensures that each customer’s data is secure when multiple users are accessing the data at the same time.
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19N.1.SL.TZ0.3a:
State the function of the control unit (CU) in the central processing unit (CPU).
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20N.1.SL.TZ0.4b:
State the part of the central processing unit (CPU) that performs the decoding.
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20N.1.SL.TZ0.8c.i:
State where the customer data is held during the process of modifying their data.
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17N.1.SL.TZ0.11d:
Outline the purpose of one application software package other than a word processing package that could be used in this office.
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17N.1.SL.TZ0.6:
Construct a logic diagram for the Boolean expression
NOT A OR B AND C.
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17N.1.SL.TZ0.9:
Define the term bit.
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20N.1.SL.TZ0.4a:
State where the program is held.
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20N.1.SL.TZ0.6:
Construct a truth table for the following logical expression.
(A XOR B) AND NOT C
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18N.1.SL.TZ0.8b:
Explain the roles of the data bus and the address bus in the machine instruction cycle.
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19N.1.SL.TZ0.4c:
State the maximum number of colours that can be represented in a computer pixel.
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19N.1.SL.TZ0.5:
Copy and complete the following truth table where:
X = A XOR B
Y = A NOR C
Z = X OR NOT Y
