Chapter 3 Flashcards
What happens in the fetch stage?
Data and instructions are given to the computer using input devices. They’re stored in RAM. In the fetch stage, they are taken from the RAM to the CPU to be processed. The Program Counter stores an address. The address is taken from the PC to the Memory Address Register using an Address Bus. After receiving the address, in order to retrieve the instruction, the MAR sends the address to the RAM using the address bus again. The RAM uses the data bus to send the instruction to the Memory Data Register. The MDR finally sends the instruction to the Current Instruction Register using the data bus. The CIR is a register in the Control Unit, which is responsible for the decode stage.
What happens in the decode stage?
The CU decodes the instruction using an instruction set. Instruction set: A set of commands that can be understood by the CPU written in machine code.
What happens in the execute stage?
The data used in the process in sent to the Arithmetic Logic Unit which preforms mathematical operations. The accumulator is a register built into the ALU with stores results of any interim calculations. The CU acts as a conductor throughout the whole FDE cycle sending signals using the control bus to components telling them when to perform their tasks.
What are the factors that can affect the performance of a CPU?
Number of cores it contains
Core: part of the CPU that contains all the components used to perform the FDE cycle
Clock speed
Number of FDE cycles performed per second
Size of cache
Cache: component that stores frequently used data and instructions
How do sensors work? Provide three examples of sensors.
Sensor captures data from its surroundings. It sends it to the analogue to digital converter to be converted into digital data. It’s then sent to the microprocessor to be compared with stored values. If it’s in range, nothing happens. If it’s out of range, a signal is sent to the actuator to carry out the physical action. The process repeats until it is manually stopped. Level, humidity, motion.
RAM ≠ ROM, how?
RAM:
Volatile, stores data and programs currently in use, contents are constantly being changed, it is possible to increase the amount of RAM a computer has
ROM:
Nonvolatile, stores programs that initially boot the computer, contents are fixed and don’t usually change, not easy to alter amount of ROM a computer has
Provide three types of secondary storage and how they work briefly:
Magnetic storage: uses the properties of magnetism to store data. Has a read/wrote head. Ex: hard drive
Optical storage: uses lasers to store data. Has a read/write head. Ex: CD, Blu-ray
Solid state storage: Created using semiconductor chips. Uses cells and transistors to store data. Doesn’t have any moving parts. Uses NAND and NOR technology. Ex: SSD
What is virtual memory?
A type of memory that can be used as an extension to the RAM.
Storing data in the cloud ≠ Storing data locally, how?
Storing data in the cloud:
Not responsible for the safety of your data, though it is basically 100% safe.
Can access the data on different devices as long as you have an internet connection.
Don’t have to buy hardware to store your data.
Can increase and decrease the amount of storage you need very easily
Storing data locally:
Buying hardware to store your data may be expensive.
Responsible for the security of your data.
Available at all times when you have local access.
Not as easy to alter the amount of storage you need.
Basic hardware to create a network:
Network Interface Card: used to connect a computer to the internet (has a MAC address)
Router,
Transmission media: cables used to transfer data in a network
A MAC address in made up of:
Manufacturer’s ID code and serial ID code
Static IP ≠ Dynamic IP, how?
Static IP doesn’t change each time the device is connected to a network.
Dynamic IP changes every time the device is connected to a network.
IPv4 ≠ IPv6, how?
IPv4 uses 32 bits to create each numerical IP address. It is separated by full stops.
IPv6 uses 128 bits to create each IP address, can contain hexadecimal characters. Separated by colons.
