Sensors
State 3 types of sensor
temperature
moisture/humidity
light
State six types of logic gate
NOT, AND, OR, NAND, NOR, XOR
State a drawback of using SSD
its longetivity/endurance
State 3 output devices
speakers, printer, touchscreen
State 3 types of secondary storage
optical, magnetic, solid state
State 2 examples of monitoring system
monitoring a patient in a hospital for vital signs such as heart rate
checking for intruders in a burglar alarm system
checking the temperature levels in a car engine
monitoring pollution levels in a river
Draw the truth table for XOR gate and NAND gate
*table*
turning street lights on at night and turning them off again during daylight
controlling the temperature in a central heating/air conditioning system
controlling the traffic lights at a road junction
operating anti-lock brakes on a car when necessary
controlling the environment in a greenhouse
State 2 components that make up an inkjet printer
a print head consisting of nozzles that spray droplets of ink onto the paper to form characters
an ink cartridge or cartridges
a stepper motor and belt which moves the print head assembly across the page from side to side
a paper feed which automatically feeds the printer with pages as they are required.
State 2 benefits of using SSD over HDD
are more reliable (no moving parts to go wrong)
are considerably lighter (which makes them suitable for laptops)
do not have to ‘get up to speed’ before they work properly
have a lower power consumption
run much cooler than HDDs (both these points again make them very suitable for laptop computers)
are very thin (because they have no moving parts)
access data considerably faster.
Give 3 examples of applications that use pressure sensor
detect intruders in a burglar alarm system
check weight (such as the weight of a vehicle)
monitor/control a process where gas pressure is important
Give an example of application/system that uses NAND gate
Automatic fan control
BONUS
BONUS
Explain how OLED works
OLEDs use organic materials (made up of carbon compounds) to create flexible semiconductors. Organic films are sandwiched between two charged electrodes (one is a metallic cathode and the other a glass anode). When an electric field is applied to the electrodes, they give off light. This means that no form of back lighting is required. This allows for very thin screens.
For each type of ROM (PROM, EPROM and EEPROM), state 2 characteristics of it
*answer*
State 4 characteristics of embedded system
Dedicated to One Task
Does Not Require Much Processing Power
Built into a Larger System
Contains Firmware that Cannot Be Easily Updated
The System Does Not Have Its Own Operating System
An Embedded System Must Contain a Processor, Memory, and I/O Capability // Dedicated Hardware
X = NOT(A OR B) OR (A AND (B XOR C))
Draw the logic circuit for the given expression, using a maximum of four logic gates.
Explain why Blu-ray discs are better than regular CD and DVDs
Blu-ray uses a blue laser, the wavelength of blue light is only 405 nanometres.
Using blue laser light means that the ‘pits’ and ‘bumps’ can be much smaller; consequently, a Blu-ray can store up to five times more data than a DVD.
Blu-ray discs automatically come with a secure encryption system which helps to prevent piracy and copyright infringement.
Describe 4 benefits of a 3D printer
State 4 differences of SRAM and DRAM
*answers*
What does 'feedback' mean? Give an example where feedback is used, including the sensor and actuator that are used.
Automatic plan watering system
Explain how a microphone works
When sound is created, it causes the air to vibrate.
When a diaphragm in the microphone picks up the air vibrations, the diaphragm also begins to vibrate.
A copper coil is wrapped around a permanent magnet and the coil is connected to the diaphragm using a cone. As the diaphragm vibrates, the cone moves in and out causing the copper coil to move backwards and forwards.
This forwards and backwards motion causes the magnetic field around the permanent magnet to be disturbed, inducing an electric current.
The electric current is then either amplified or sent to a recording device. The electric current is analogue in nature.
Describe how a laser printer makes use of a buffer
The print instructions and data are sent by the laptop to a buffer (at laptop speed)
The data is transferred from the buffer to the printer (at printer speed) …allowing user to continue using the laptop // and allowing processor to continue processing …instead of waiting for relatively slower printer
When the buffer is empty an interrupt is sent to the laptop • …requesting more data
Explain the principle operation of HDD
The surface of the platter/disk is divided into concentric tracks / circles
The surface of the platter/disk is divided into sectors
The data is encoded as a magnetic pattern for each block
When writing to disk, a variation in the current in the head produces a variation in magnetic field on the disk
When reading from disk, a variation in magnetic field produces a variation in current through the head