Chapter 2 - Computer Architecture and Secondary Memory Flashcards
What are registers?
The smallest and the fastest units of memory. They exist within a CPU and store what the CPU is working on at the moment.
What are the registers in the CPU?
MAR (memory address register), MDR (memory data register), CIR (current instruction register), CU (control unit), ALU (arithmetic and logic unit), ACC (accumulator)
What does the MAR do?
It stores the address which needs to be read or written to.
What does the MDR do?
It stores data that has been read or needs to be written into the RAM.
What does the current instruction register do?
It stores the instruction that has been transferred to the MDR and is about to be decoded and then executed.
What does the control unit do?
- Decodes instructions into opcodes
- Coordinates with other components of the CPU and synchronises the movement of data between registers
- Sends read/write signals to control when data has to be read or written
What does the ALU do?
- It carries out instructions to do with arithmetic and logic
- It reads operands and writes the results of its operations into registers
What does the accumulator do?
The accumulator stores intermediate logical or arithmetic data in multi-step calculations.
What is RISC computer design?
The idea here was that the best way to improve performance would be to simplify the processor workings as much as possible.
What is CISC computer design?
The idea that making the CPU more complex and supporting a larger number of instructions would lead to an increased performance.
What is pipelining?
The idea to keep the components of the CPU working with data continuously.
What three factors can be used to identify CPUs?
- Speed
- Instruction set
- Width of the bus (word size)
Primary memory can be _ _ by the CPU while secondary memory _.
directly accessed, cannot
