1 Hardware and Communication Flashcards
What is the purpose of the CPU?
To carry out all the mathematical and logical operations needed to execute instructions.
What are the components in the CPU diagram?
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A - ALU
B - Registers
C - Control Unit
D - Input Devices
E - Output Devices
F - Memory
What is the purpose of the Arithmetic and Logic Unit
Responsible for calculations and logic operations.
What is the purpose of the control unit?
It manages the execution of machine code by sending control signals
What is the purpose of the control bus?
The control bus transmits the signals being sent out by the control unit to all connected devices, including the hard drive, graphics cards etc
What is a register? What is the difference between a special register and general purpose register?
A small block of memory used for temporary storage.
Special registers have a specific role to play.
General purpose registers can be used as programs run however the programmer wishes to utilise it in an algorithm
Name 5 special purpose registers
Program Counter
Memory Address Register
Memory Data Register
Current instruction register
Accumulator
What is the purpose of the program counter
To store the value of the next instruction to be accessed from the main memory.
This value is passed to the MAR before the instruction is fetched.
What is the purpose of the MAR?
Instructions that need processing are stored in the main memory and need “fetching” into the special registers in order to be executed.
The MAR contains the memory address of the memory location that needs to be accessed, this can be to both retrieve and store data.
What is the purpose of the MDR?
When an instruction or data is fetched from the memory it needs to be stored in a special register.
This is the purpose of the MDR.
What is the purpose of the CIR?
The data or instruction in the MDR is stored in the CIR. This means that the MDR is free to be reused to fetch another instruction while the “current instruction” is decoded and executed.
What is the purpose of the accumulator?
Used by any instruction which performs a calculation. The results of these calculations are stored in the ACC.
How does the CPU make use of “cache memory”?
Cache memory is high speed storage for frequently used data or instructions. Storing such data and instructions in cache memory eliminates the need to perform time consuming fetch operations each time they are accessed.
What is the difference between the different levels of cache memory?
Level 1 - Fastest but smallest. Usually embedded in the CPU
Level 2 - Usually higher capacity than level 1but slower. Can be on the CPU or on a separate chip.
Level 3 - The slowest and largest area of cache memory, usually shared by all cores on a processor.
