Computer Systems - The CPU Flashcards
What is the CPU and what does it do?
The brain of the computer system that process all of the data and instructions that make the system work
What does the processing power of the CPU depend on?
Clock speed
Number of cores
Cache size and type
What does the CPU architecture describe?
The main components of the CPU, how they interact with each other, and with other parts of the computer system
What are the two types of CPU architecture?
Von Neumann - need to know this one
Harvard
What are the 5 main parts of the CPU?
The control unit (CU)
The arithmetic Logic unit (ALU)
Cache
The clock
Buses
What is the control unit?
Is the overall control of the CPU - its main job is to manage the fetching, decoding and execution of program instructions by the following the Fetch-Execute Cycle.
What does the Control Unit (CU) do?
Controls the flow of data inside the CPU (ALU, cache, registers) and outside the CPU (main memory and input/output devices (I/O devices))
What does the Arithmetic Logic Unit do?
Completes simple maths (addition, subtraction, multiplication, division) and compares the size of numbers
Performs logic operations (AND, OR and NOT) and binary shifts
How do registers help the ALU?
The registers are used to store immediate results of calculations
What is cache?
Very fast memory in the CPU - slower than registers but faster than RAM
What does cache do?
Stores regularly used data so the CPU can access it quickly when needed
How does the CPU request data?
It checks the cache first to see if the data is there, if not, it will get the data from RAM
What is bad about RAM?
They have low capacity and are expensive compared to RAM and secondary storage
What does the clock do?
Sends out a signal that continually cycles between 1 and 0 - usually at a constant rate
The signal is then used to synchronise when instruction will be carried out (like a metronome)
What is clock speed?
The number of clock cycles (or clock ticks) per second
