MODULE 1: Basic structure of computer & Machine instructions and programs Courtesy: Text book: Carl Hamacher 5th Edition Subject
Functional Units Arithmetic and logic Input Memory Output Control I/O Processor Figure 1.1. Basic functional units of a computer.
Basic operational concepts : A Typical Instruction • Add LOCA, R0 • Add the operand at memory location LOCA to the operand in a register R0 in the processor. • Place the sum into register R0. • The original contents of LOCA are preserved. • The original contents of R0 is overwritten. • Instruction is fetched from the memory into the processor – the operand at LOCA is fetched and added to the contents of R0 – the resulting sum is stored in register R0.
Separate Memory Access and ALU Operation • Load LOCA, R1 • Add R1, R0 • Whose contents will be overwritten?