1.1 System Architechture Flashcards
What is the CPU?
The CPU is the main bit of the computer that performs the fetch decode execute cycle and that has the ALU, CU and registers.
Describe what happens in the fetch-execute cycle.
The CPU needs to retrieve data from the memory. The signal goes from the PC to the MAR then to the RAM outside the CPU or the cache. The data is then loaded into the MDR. The data is then copied over to the control unit. The address in the program counter is incremented to point at the next instruction. The instruction is then decoded by the CU. Then the CU updates the concerned registers and signals are sent to retrieve or send data. If the command was mathematical, The ALU executes the instruction, and the result is loaded into the ACC.
What is the ALU?
The Arithmetic Logic Unit is responsible for carrying out arithmetical calculations and logical comparisons.
What is the CU?
The Control Unit decodes instructions and sends signals to control how data is moved around the CPU.
What is the Cache and how does Cache size affect CPU performance?
Cache is memory in the CPU and next to the CPU that stores frequently used instructions and data. The bigger the cache, the more information you can store in the cache and that means the CPU doesn’t need to spend time going to the RAM.
What are registers?
Registers are tiny areas of extremely fast memory located in the CPU designed for a specific use.
Explain Von Neumann architecture.
The traditional computer architecture that forms the basis of most digital computer systems. Instructions are fetched, decoded and executed one at a time.
What is the MAR?
The Memory Address Register holds the address of data ready for use by the memory data register or address of an instruction passed from the program counter. It is step 2 of the fetch, decode, execute cycle.
What is the MDR?
The Memory Data Register holds the data fetched from or to be written to the memory. It is step 3 of the fetch, decode, execute cycle.
What is the PC?
The PC holds the address for the next instruction.
What is the ACC
The Accumulator holds the results for calculations.
What is Clock Speed and how does it affect CPU performance?
This is measured in Hertz. It means the number of fetch- decode-execute cycles that can be completed per second. The faster the clock speed the more tasks can be completed in a shorter amount of time.
What are cores and how do they affect CPU performance?
Cores are exact copies of the CPU. The more cores the more tasks can be completed at the same time. However, the cores need time to communicate and not all programs are built for multi core processors.
What is an embedded system?
A computer which has been built to a very dedicated and specific use. It is not easily changed.
What are some examples of embedded systems?
Microwave, Washing machine and traffic lights.
