1.1. Information representation
A subsection of Computer Science, 9608, through 1. Theory Fundamentals
Listing 10 of 54 questions
A digital camera takes a bitmap image. The image is 2000 pixels wide by 1000 pixels high with a colour depth of 24-bits. Calculate an estimate of the file size for the image. Give your answer in megabytes. Show your working. Working Answer MB A second image is taken, this time in black and white. It has the same number of pixels, but the file size is smaller. Explain why the file size is smaller. The digital camera allows a user to add text to an image. The text is encoded as ASCII values. The table shows the ASCII denary values for five characters. Character ASCII denary value a b c d e Give the 8-bit binary value for the ASCII character ‘b’. Complete the table by writing the ASCII denary value for the character ‘t’ and its hexadecimal equivalent. Character t ASCII denary value Hexadecimal value
9608_s20_qp_11
THEORY
2020
Paper 1, Variant 1
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Four greenhouses are used to grow tomatoes. The temperature inside each greenhouse should be kept between 10 and 20 degrees Celsius inclusive. Each greenhouse has a temperature sensor. A computer system is programmed to control each greenhouse’s temperature by: • turning on the heater and closing the ventilation when the temperature falls below 10 degrees • turning off the heater and opening the ventilation when the temperature rises above 20 degrees. State the name given to the type of system described. Justify your answer to part . The computer system stores the temperature readings for the four sensors in two’s complement form and in four eight-bit memory locations with addresses 701 to 704. Greenhouse 1 Greenhouse 2 Greenhouse 3 Greenhouse 4 State the greenhouse numberwhere the temperature is out of range and give the valueof these temperaturein denary. The status of the heaters and the ventilation is shown at location 700. • A value of 1 means that the heater is on. • A value of 0 means that the heater is off. • A value of 1 means that the ventilation is open. • A value of 0 means that the ventilation is closed. The status of the heaters is shown in the most significant four bits; the status of the ventilation is shown in the least significant four bits. The pattern of bits at location 700 shows that the heater for greenhouse 3 is on and the ventilation for greenhouse 1 is open. Greenhouse number Heater Ventilation Show the pattern of bits when the heater is on for greenhouses 1 and 2 only and no ventilation is open. The table shows assembly language instructions for the greenhouse computer system that has one general purpose register, the accumulator (ACC). Instruction Explanation Label Op code Operand LDM &n Load the hexadecimal number n to ACC LDD Load the contents of the location at the given address to ACC STO Store the contents of ACC at the given address AND &n Bitwise AND operation of the contents of ACC with the hexadecimal number n LSL #n Bits in ACC are shifted denary number n places to the left. Zeros are introduced at the right hand end CMP &n Compare the contents of ACC with the hexadecimal number n JPE Following a compare instruction, jump to or if the compare was True : Labels an instruction If the bit for a greenhouse’s heater and the bit for the same greenhouse’s ventilation are both set to 1, a routine at label ERROR is executed. This routine has not been provided. These assembly language instructions check for an error in the greenhouse 1 system. LDD AND &88 CMP &88 JPE ERROR Explain the purpose of each instruction. Write the assembly language instructions to check for an error in the greenhouse 2 system.
9608_s21_qp_32
THEORY
2021
Paper 3, Variant 2
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A touch screen has three squares where a selection can be made: T S U The x-coordinate of the centre of the three squares is held in three memory locations: Address Memory contents S 0000 1011 0100 T 0010 0101 0100 U 0100 0110 1100 Give the hexadecimal value of the memory contents for U. Convert the denary number 40 into binary. Bitmap graphics are used to represent squares S, T and U. These can be saved in a number of different image resolutions. Give the number of bits required to store each pixel for a black and white bitmap. Identify how many bits are required to store each pixel for a 256-colour bitmap. Explain your answer. Images can be compressed to reduce file size. Describe how lossless compression techniques work. Describe how lossy compression techniques work.
9608_w15_qp_12
THEORY
2015
Paper 1, Variant 2
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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_11
THEORY
2016
Paper 1, Variant 1
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Questions Discovered
54