The CPU Flashcards
What is the CPU?
“Brain of the computer” Processes all the data and instructions that make the system work.
What does the Processing power of the CPU depend on?
Clock Speed, Number of cores and cache size
What is the CPU architecture
The CPU architecture describes the main components, how they interact with each other and with other parts of the computer.
What are the three main parts of the CPU?
The Control Unit (CU)
The Arithmetic logic Unit (ALU)
The Cache
What is The Control Unit (CU) and what does it do?
The Control Unit is in overall control of the CPU. Main job is to manage Fetching, decoding and executions of program instructions by following fetch execution cycle.
It also controls the flow of data inside the CPU ( to register ALU cache) and outside the CPU ( to main memory and input/output devices)
What is the Arithmetic Logic Unit (ALU) and what does it do
Containing the accumulator register the Arithmetic logic Unit (ALU) does all the calculations, completes simple addition and subtraction, compares the size of numbers and can do multiplications and divisions using repeated addition and subtraction. It performs logic operations such as AND, OR or NOT and binary shifts.
What is The Cache and what does it do?
The cache is very fast memory in the CPU. It is slower than Registers but faster than RAM. It stores regular used data so the the CPU can access it quickly the net time its needed. When the CPU requests data, it checks the cache first to see if the data is there. If not it will fetch from RAM.
Different Levels of Cache
Different levels of cache memory include
L1 - quickest but has the lower capacity
L2 - is slower than L1 can hold more
L3 - is slower than L2 but can hold more
What is Von Neuman architecture?
Von Neuman describes a system where the CPU runs programs stores in the memory. Programs consist of instructions and data which are stored in the memory address. It uses memory for both the data and instructions
What is the Memory address register (MAR) ?
(MAR) holds the memory address abut to be used by the CPU. The address might point to the data or the CPU instruction
What is the Memory data register (MDR) ?
(MDR) holds the actual data or instruction. This may have been fetched from the memory, or be waiting to be written or memory.
What is the function of Memory?
To hold instruction and program data
What is the Program Counter (PC) and what does it do?
It holds the memory Address of instruction each cycle
What do CPUs follow?
The Fetch-Execute Cycle (otherwise known as the Fetch-Decode-Execute Cycle)
What is the Fetch?
The copying of the memory address from the (PC) to the (MAR). The copying of the instruction from the (MAR) to the (MDR). Then incrementing the (PC) to point to the next address of the next instructions ready for the next cycle
