Computer Organisation and Architecture Flashcards
What is the processor?
- Executes program instructions in order to run applications
What is the main memory?
- Includes RAM, random access memory
- Includes ROM, read only memory
- Stores program instructions and frequently used data
- Much faster than secondary storage
What is a bus?
- A series of parallel wires that connects internal components of a computer system, allowing signals to be passed between them
What is the width of a bus?
- The number of parallel wires in a bus
- It has a direct relationship to the number of bits it can transfer
What is the address bus?
- Used to transport memory addresses
- Specifies where in memory, data is to be sent or retrieved
What happens if you increase the width of the address bus?
- Increases the range of addresses that can be specified by double
What is the data bus?
- Sends data and instructions to and from the components of a computer system
What happens if you increase the width of the data bus?
- Increases the volume of data that can be transferred at any one time
What is the control bus?
- Used to carry control signals that regulate the operation of the computer system
- Carries the computer’s clock signal
What is an I/O controller?
- Pieces of hardware that control the communication of data between the processor and external hardware devices
What is Harvard architecture?
- The processor uses two separate main memory locations
- One for instructions and the other for data
- These can be given characteristics such as:
- Instructions could be made read-only so that instructions cant be changed
When is Harvard architecture used most?
- Embedded systems such as digital signal processing
What is Von Neumann architecture?
- Both instructions and data are stored together in the same memory
Why might Von Neumann perform worse than Harvard architecture?
- The same buses have to be shared for fetching both instructions and data in Von Neumann
- Therefore, systems based on Von Neumann often perform worse than those on Harvard
When is Von Neumann architecture used most?
- Everyday general-purpose computer systems like laptops
What is the stored program concept?
- Machine code instructions stored in main memory are fetched and executed serially by a processor that performs arithmetic and logical operations
What is inside a processor?
- An arithmetic logic unit (ALU)
- A control unit
- Registers
What is the arithmetic logic unit (ALU)?
- Performs arithmetic and logic operations
- Arithmetic includes maths operations
- Logic includes Boolean operations
What is the control unit?
- Responsible for controlling the various components of the processor
- Controls the fetch-execute cycle
What are registers?
- Small storage locations used to hold data temporarily
- Have high read and write speeds
What are general-purpose registers?
- Used as storage for any data that is required by instructions during execution
What are special-purpose registers?
- Assigned to the storage of specific information
- Examples include:
- Program counter
- Current instruction register
- Memory address register
- Memory buffer register
- Status register
What is the program counter (PC)?
- Holds the memory address of the next instruction to be execute in the fetch-execute cycle
What is the current instruction register (CIR)?
- Holds the instruction that is currently being executed by the processor