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4 questions · 11 marks
Computers manipulate binary patterns.
Convert the binary pattern 1010 0100 to denary.
Award one mark for:
164
Why: Correct: 128 + 32 + 4 = 164 (1).
37
Why: Reads the place values from the wrong end (the left-hand bit as 1), so the value is wrong.
3
Why: Counts the 1s instead of adding their place values.
Files can be compressed before they are stored.
Define the term lossless compression.
Award one mark for any of the following up to a maximum of two marks:
Allow 'the compressed file takes up less storage space' for the first mark.
The second and third bullets are two ways of making the same point: award a maximum of one mark for them, so a response that says no data is lost and that the original file can be restored, but does not say the file is smaller, scores one mark.
Do not accept descriptions of lossy compression, e.g. 'it removes data that is not needed to make the file smaller'.
Ignore reference to download/transmission times, bandwidth and streaming, as these are benefits of compression and not part of the definition.
Lossless compression reduces the size of a file without permanently removing any data, so the original file can be restored exactly.
Why: Reduces the size of a file (1) and no data is lost, so the original can be restored exactly (1); maximum of two marks reached.
It makes a file smaller so it downloads more quickly.
Why: Reduces the size of a file (1); the faster download is ignored as a benefit, not part of the definition.
It removes data that is not needed to make the file smaller.
Why: Describes lossy compression, which the do-not-accept line rules out, so the mention of making the file smaller is not credited.
A device driver is software that allows the operating system to control a piece of hardware. Device drivers are often written in a low-level programming language.
Describe one reason why a low-level programming language is suitable for writing a device driver.
Award up to two marks for a linked description such as:
Extra detail, such as naming the device the driver controls, is not needed to earn the marks.
Do not accept 'it is closer to machine code' on its own: it must be developed to show how this helps the driver, e.g. it can control the hardware directly.
Do not accept 'it is faster/quicker' with no link to the hardware/device, e.g. the device responds quickly.
Do not accept 'it is easier to learn', 'it is easier to debug' or 'it takes less time to write'.
Low-level instructions can manipulate the hardware and memory directly (1) so the driver can control the specific device it was written for, such as a sound card (1).
Why: Point about direct control of hardware/memory (1) linked to controlling the specific device (1). The named device is extra detail and is not needed.
Low-level instructions can manipulate the hardware directly.
Why: Correct point (1) but no linked development saying how this helps the device driver.
It is closer to machine code so it runs faster than a high-level language.
Why: 'Closer to machine code' is not developed into how this helps the driver, and 'runs faster' is not linked to the hardware/device, so no mark.
A delivery company is developing a drone to deliver small parcels to customers' homes. The drone has sensors, a camera, a GPS receiver and rotors, and it must fly autonomously and avoid obstacles.
Discuss the use of embedded systems in the delivery drone.
Your answer should include:
Indicative content
What embedded systems are used for in the drone
Benefits of using embedded systems in the drone
Any drawbacks or limitations of using embedded systems in the drone
Levels
Additional guidance
An embedded system is a computer built into a larger device that performs a dedicated function. The delivery drone contains several embedded systems. The flight controller is an embedded system that takes data from the drone's sensors and adjusts the speed of each rotor, so the drone stays level and stable while carrying a parcel. The GPS embedded system calculates the drone's position and works out the route to the customer's address. The camera embedded system takes images that are processed to spot obstacles such as trees or overhead cables, and the sensor embedded systems measure the distance to the ground so the drone can land safely. These systems are dedicated to one task each, so they respond quickly, which allows the drone to change direction in time to avoid an obstacle. They are also small and light and use little power, so the drone can fly further on one charge and deliver more parcels. Because each embedded system is built into the drone, the drone can fly autonomously and the company does not need a pilot for every delivery. However, the embedded systems have limited processing power and storage, so the drone may not be able to run complex obstacle-recognition software and might not recognise an unusual obstacle. Their software is held in ROM, so fixing a bug is difficult and the drone may have to be returned or connected to a computer to be updated. If an embedded system fails, the drone could crash, which could injure someone or damage property. Overall, embedded systems make the delivery drone possible because they are small, light and dedicated, but their limitations mean the drone cannot do every task that a general-purpose computer could.
Why: Definition of an embedded system (1); uses with reasons applied to the drone, including the flight controller, GPS, camera and sensors (1); benefits linked to weight, power, responsiveness and autonomous flight (1); drawbacks linked to limited processing/storage, ROM updates and crash risk (1); sustained lines of reasoning connect the uses, benefits and drawbacks to the delivery drone throughout, so Level 3, 6 marks.
An embedded system is a small computer inside a device that does one job. The drone uses a flight controller embedded system to keep it balanced and change the rotor speeds, and a GPS embedded system to find the address. The camera embedded system helps it avoid obstacles. Embedded systems are small and light and use little power, which is good for a drone because it has to stay in the air. A drawback is that they have limited processing power, so the drone might not recognise an obstacle.
Why: Definition (1); some uses with a little linkage to the drone, flight controller and GPS (1); a benefit linked to the drone staying in the air (1); one drawback linked to obstacle recognition (1). However, the points are brief and mostly asserted, with only some linkages, so Level 2, 3 marks.
The drone uses embedded systems to connect to Wi-Fi and play videos. They are good because you can install games on them.
Why: No creditworthy point. The answer gives general-purpose computer uses (Wi-Fi and playing videos) that are not linked to the drone's delivery function, and claims that new software or games can be installed, which the mark scheme says not to accept. No drone-relevant use, benefit or drawback is given, so Level 0.
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