Components of the processor Flashcards
What is the processor?
one of the most important parts of a computer
it allows for the processing of instructions and data which then allows programs to run
What are registers?
small temporary storage units within the processor which often have a specific purpose
are extremely fast pieces of memory with a much faster read/write time than other components such as cache or RAM
A downside to registers
have very limited capacity which makes them great for storing small pieces or information used in executing code but little else
What are units?
components that process the data
have a critical job to do each one performing a specific job as part of the execution if instructions
What are buses?
are like wires within the processor as they connect the various components together and allow for the transfer of data between the components
Program Counter (PC)
register
holds address of next instruction to be executed
value in the pc is incremented at the end of the fetch stage or it is overridden by a selection statement
Memory Address Register(MAR)
register
holds address of next piece of data to be retrieved from RAM
obtains its value from the pc in the fetch stage or decode unit in the execute stage
Memory Data Register(MDR)
register
all data passing in and out of processor must pass through through the MDR
is updated whenever data enters or is about to exit the processor
Current Instruction Register(CIR)
register
stores instruction currently being executed
receives value from MDR in the fetch stage
Accumulator(ACC)
set of general purpose registers in the CPU which are used to store inputs and outputs of ALU
consider ALU as single register
Arithmetic Logic Unit(ALU)
component responsible for performing logical and numerical calculations within the processor
responsible for performing comparisons arithmetic and concatenation as well as many other functions
input values for the ALU are stored in the ACC and the output values are also returned to the ACC
Decode Unit
responsible for splitting the instruction fetched from memory into two parts the opcode and the operand
What is opcode?
the task that the processor needs to carry out such as LOAD, STORE, ADD etc
What is operand?
the data or address of the data that the task refers to
Control Unit
responsible for synchronising all the activities within the CPU
sends read and write signals to RAM to control the flow of data in and out of the processor so that the data doesn’t get corrupted
