Weekend Revision (Chapter 1 - Paper 1) Flashcards
What is the Arithmetic Logic Unit?
ALU, performs arithmetic calculations and makes logical decisions (AND/OR/NOT)
What does the Control Unit?
Sends signals to control how data moves around the CPU.
What does Cache do?
Provides fast access to frequently used instructions and data.
What are registers?
Tiny, super-fast pieces of onboard memory inside the CPU, each with a specific purpose.
What are the four registers?
Accumulator
Memory Address Register
Program Counter
Memory Data Register
What happens in the ‘Fetch’ stage?
Program counter checked for the memory address of the next instruction
MAR fetches instruction from RAM and brings it to MDR
What is the ‘decode’ stage?
Control Unit decodes to figure out what the CPU needs to do.
What is the ‘execute’ stage?
Carrying out machine code instruction.
Properties of embedded systems?
Low Power consumption
Small size
rugged operating systems
low cost per unit
What are the different types of Primary storage?
RAM, ROM, Registers and Cache.
What is the function of secondary storage?
Holds operating system, programs and data when they are not in use.
What is tertiary storage used for?
Used to back up and archiving large amounts of data.
What are some characteristics of primary storage?
Mainly volatile
relatively small capacity compared to secondary
What are some characteristics of secondary storage.
Non volatile
High capacity
What is ROM?
Small piece of read only memory located on the motherboard.
Non-Volatile
Holds startup instructions for computer.
What is RAM?
Temporary storage of instructions and data,
Holds data currently being used by the processor.
Volatile
Much faster to read from than the hard drive.
When is virtual memory used?
When RAM is filled up.
Why is virtual memory slower than RAM?
Needs to be fetched from RAM when user wants to put the program into use.
Why is secondary storage required?
ROM is read only and RAM is volatile.
What is secondary storage used for?
Storage of programs and data when the computer is powered off.
Backing up or archiving data.
What are the positives of Optical storage?
Cheap, Lightweight, Portable
What are the negatives of optical storage?
Very slow, prone to scratches.
What are the positives of magnetic storage?
Cheap, Large capacity
What are the negatives of magnetic storage?
Slow access times.
Fragile
