Systems Architecture

Systems Architecture

1. Registers

   • MDR
     • Memory Data Register
     • Holds actual data or an instruction that is fetched from or waiting to be written to memory
   • MAR
     • Memory Address Register
     • Holds the address of the instruction or data to be fetched or stored
   • CIR
     • Current Instruction Register
     • Holds the current instruction to be executed
   • PC
     • Program Counter
     • Holds the address of the next instruction
   • Accumulator
     • Special purpose memory for results from the ALU

2. CPU

   • The Control Unit
   • The Arithmetic Logic Unit
   • The Registers
   • The Cache