1
Name 3 types of sensors
temperature, pressure, infra-red, sound, etc.
Name all types of logic gates
NOT, AND, OR, NAND, NOR and XOR
Identify one example of an embedded system
Washing machine
Name 3 categories of secondary storage
Magnetic, solid-state, optical
Draw the truth table for XOR and NAND gates
*draw on the board*
Give an example of where capacitive touchscreens are used.
Give an example of where resistive touchscreens are used.
capacitives: mobile devices, computers and laptops
resistive: POS systems, public kiosks
State 1 benefit of HDD and where it is suitable to be used.
Longevity
In server where there are many read & write operations per day
Differentiate between a monitoring and a control system and give two examples for each system.
*answer*
State 3 drawbacks of an embedded system.
cannot be easily upgraded by the owner
usually is thrown away when damaged
need a specialist/expensive to repair
cannot be easily adapted to other functions
Differentiate between RAM & ROM, state all types of RAM, all types of ROM, and 1 characteristic for each type
*answer*
State 3 benefits of SSD.
speed, noise, durability, size & weight, efficiency
BONUS
BONUS
What is feedback, and why is it important? Explain your answer with an example.
Feedback ensures that a system operates within set criteria / constraints by enabling system output to affect (subsequent) system input thus allowing conditions to be automatically adjusted.
Explain the characteristics of solid-state memory (flash drive)
A flash memory stick stores data by using floating gates that trap electrons to represent 0s and 1s.
A control gate allows or blocks the movement of electrons, depending on whether you are writing or erasing data.
The cells are arranged using NAND or NOR gates, and each cell uses two transistors.
Describe the principal operation of an optical disc.
The data is stored in ‘pits’ and ‘lands’ on the spiral track.
A red laser is used to read and write the data.
Reflected light is then encoded as a bit pattern
Describe the principle operation of a microphone
The microphone has a diaphragm
The incoming sound waves cause vibrations of the diaphragm
… causing a coil to move past a magnet
An electrical signal is produced
Describe the principle operation of a 3D printer
Additive manufacturing
Uses a digital 3D model or a Computer Aided Design (CAD) (file)
Builds up the model one layer at a time
...starting from the bottom • ...using x, y and z co-ordinates
The material is fused/cured together layer by layer
Describe the components of a hard disk drive and how data is being read.
magnetized platters, spindle, read/write arm, head arm, aluminum box
When reading from disk, a variation in magnetic field produces a variation in current through the head
Bonus question—1.5x points
What is a memory buffer when using a hard disk drive?
The computer and the hard disk drive transmit and receive at different speeds. // The computer transfers data faster than the HDD can receive
The buffer is used for temporary storage … so that the computer can transfer data to the buffer at the higher speed … and is not held up waiting for data to transfer
… and so that data is transferred to the hard disk drive from the buffer at the slower rate
A road bridge has a weight limit and a height limit for vehicles. For example, a vehicle must weigh less than 10000kg and must have a height of less than 3m.
The bridge has a warning system. If a vehicle is approaching the bridge and it exceeds one or both limits, a sign displays a warning telling the driver of the vehicle to stop.
Identify two different sensors that could be used by the system and describe how each sensor is used by the system.
Infra-red sensor • Measure / check the height of the vehicle
Pressure sensor • Measure / check the weight of the vehicle