Systems Architecture Flashcards
What is the purpose of the CPU
fetch, decode and execute instructions
What is the Fetch-Execute cycle
The Fetch-Execute Cycle is the cycle that the CPU runs through billions of times per second to make a computer work
What happens during the fetch stage
the next instruction or data must be fetched from the computer’s memory (RAM)
What happens during the decode stage
the CPU needs to work out what is required from the instruction
What happens during the execute stage
the CPU will carry out the instruction that was fetched
What are the components of the CPU
-Arithmetic Logic Unit (ALU)
-Control Unit (CU)
-Cache
-Registers
What does the Arithmetic logic unit do
Performs arithmetic operations
What does the control unit do
-Coordinates how data moves around the CPU by sending a signal to control the movement of the data
-Decodes the instructions fetched from memory
What does the cache do
Very small, very fast memory located in the CPU which is used to provide quick access to frequently used instructions and data
The more cache there is the more data can be stored which …
Speeds up the performance of the CPU
What do the registers do
Extremely small, extremely fast memory located in the CPU
What is the Von Neumann architecture
What are 4 main registers
The Program Counter (PC)
The Memory Address Register (MAR)
The Memory Data Register (MDR)
The Accumulator (ACC)
What does the program counter do
Holds the memory address of the next instructions to be executed
What does the MAR do
Holds the memory address of where data or instructions are to be fetched from
What does the MDR do
Stores the data or instruction which has been fetched from memory
What does the Accumulator do
Stores the results of any calculations that have taken place in the Arithmetic Logic Unit
What are the common characteristics of the CPU
Clock Speed
Cache Size
Number of Cores
The clock speed is measured in …
Hertz
What does the clock speed do
The clock speed measures the number of fetch-decode-execute cycles that can take place in 1 second
The faster the clock speed …
the more instructions can be fetched and executed per second
The larger the cache size …
the more frequently used instructions or data can be stored
Cache also has a significantly faster …
read/write speed than RAM
What is a core
A core works like it is its own CPU
