1.1. Information representation
A subsection of Computer Science, 9608, through 1. Theory Fundamentals
Listing 10 of 54 questions
Convert the denary number 46 to an 8-bit binary integer. Convert the denary integer – 46 to an 8-bit two’s complement form. Convert the denary number 46 into hexadecimal. Binary Coded Decimal (BCD) is another way of representing numbers. Describe how denary integers larger than 9 can be converted into BCD. Give an example in your answer. Describe how an 8-bit BCD representation can be converted into a denary integer. Give an example in your answer.
9608_w16_qp_13
THEORY
2016
Paper 1, Variant 3
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Each of the following bytes represents an integer in two’s complement form. State the denary value. 0111 0111 Denary 1000 1000 Denary Express the following integer in two’s complement form. -17 State in denary, the range of integer values that it is possible to represent in two’s complement integers using a single byte. Lowest value Highest value Convert the following denary integer into Binary Coded Decimal (BCD). A 3-digit BCD representation has been incorrectly copied. It is shown as: State how you can recognise that this is not a valid BCD representation. Describe a practical application where BCD is used.
9608_w17_qp_11
THEORY
2017
Paper 1, Variant 1
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Each of the following bytes represents an integer in two’s complement form. State the denary value. 0111 0111 Denary 1000 1000 Denary Express the following integer in two’s complement form. -17 State in denary, the range of integer values that it is possible to represent in two’s complement integers using a single byte. Lowest value Highest value Convert the following denary integer into Binary Coded Decimal (BCD). A 3-digit BCD representation has been incorrectly copied. It is shown as: State how you can recognise that this is not a valid BCD representation. Describe a practical application where BCD is used.
9608_w17_qp_13
THEORY
2017
Paper 1, Variant 3
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The bit depth of an image dictates how many different colours can be represented by each pixel. State the number of different colours that can be represented by a bit depth of 8 bits. One binary colour is represented by 0100 1110 Convert the unsigned binary number 0100 1110 into denary. Convert the denary number −194 into 12-bit two’s complement. Convert the Binary Coded Decimal (BCD) value 0110 1001 into denary. Identify one practical application where BCD is used. One example of a character set used by computers is ASCII. Describe how one character is represented in a character set. Data can be compressed using either lossy or lossless compression. Tick (✓) one box in each scenario to identify whether lossy or lossless compression should be used. Justify your choice. A program written in a high-level language. Lossy Lossless Justification A photograph that needs to be emailed to a friend. Lossy Lossless Justification You need to upload a video that you have created to a website. Lossy Lossless Justification
9608_w19_qp_11
THEORY
2019
Paper 1, Variant 1
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Different types of data can be represented in a computer system. Numeric is one type of data. Convert the following denary number into Binary Coded Decimal (BCD). Convert the following two’s complement binary integer into denary. Convert the following hexadecimal number into denary. AB Character is another type of data. The following tables show part of the ASCII code character set. Character Denary value Character Denary value A a B b C c D d E e Describe how the computer uses ASCII codes to represent characters. Convert the following string into ASCII codes. Bed Give the denary ASCII code for the following character. H
9608_w20_qp_12
THEORY
2020
Paper 1, Variant 2
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Convert the following two’s complement binary integer into denary. Show your working. Working Answer Convert the following unsigned binary integer into hexadecimal. Convert the following denary integer to Binary Coded Decimal (BCD). Give two examples of practical applications of BCD. An encryption routine replaces each character in a short message with a different character. For example, the following table shows how the routine encrypts the word ‘HELLO’ by adding 3 to the ASCII denary value of each character. Original character H E L L O ASCII denary value ASCII denary value + 3 Encrypted character K H O O R The ASCII value of the character A is 65. Complete the table to show how the routine will encrypt the word ‘WANDS’. Original character W A N D S ASCII denary value ASCII denary value + 3 Encrypted character
9608_w21_qp_13
THEORY
2021
Paper 1, Variant 3
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A group of students broadcast a school radio station on a website. They record their sound clips in advance and email them to the producer. Describe how sampling is used to record the sound clips. The students use software to compress the sound clips before emailing them. Circle your chosen method of compression and justify your choice. Lossy / Lossless Justification: Students also email images to the radio station for use on its website. These are compressed before sending using run-length encoding (RLE). Explain what is meant by run-length encoding. The following diagrams show: • the denary colour code that represents each colour • the first three rows of a bitmap image Colour symbol Colour code B W B B B B B B B B B B W W W B B B B B B B B B B B B W W W W W W B B B B B B B B W W W W W W W W W … Show how RLE will compress the first three rows of this image. Row 1: Row 2: Row 3:
9608_s16_qp_11
THEORY
2016
Paper 1, Variant 1
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Questions Discovered
54