Registers And FDE Definitions Flashcards
Address bus
Address of memory location that the CPU will read from and write to
Control bus
Command signals from control unit
Data bus
Value being read from or written to memory (unidirectional)
Registers
They are built into the CPU chip to temporarily store memory addresses, instructions or data. They are used in the FDE cycle for specific purposes.
RAM
Consists of storage locations and each location has its own unique memory address where program instructions or data is stored.
CPU
Consists of CU, ALU and registers. Carries out the FDE cycle.
Control unit
Decodes instructions received from main memory and coordinates actions of others parts of the CPU in order to execute them.
ALU
Performs arithmetic and logic operations on data.
Memory address register
Address of memory location of data that is to be fetched or stored
Memory data register
Data being read from or written to memory.
Accumulator
Results of the ALU
Program counter
Memory address of the current instruction. Increments by 1 each cycle
Current instruction register
Instruction that is currently being processed.
Fetch
Program counter increments by 1. Control unit places memory address of next instruction into the MAR. The instruction gets transferred to the RAM via the address bus. Control unit sends a ready signal to RAM along control bus. RAM receives signal and copies content of the memory location indicated by the address bus onto the data bus. The data is then stored in the MDR. Instruction gets stored in the current instruction register
Decode
Control unit decodes the instruction and the ALU does the calculations and holds them in the accumulator.
