S5-2.2 Basic Computer Organization & Control

Work through these

• Instruction codes and stored program organization

  The stored program idea, which is the reason a computer is general purpose at all. Every remaining item in this topic is an elaboration of it.

• Computer registers and computer instructions

  The registers a machine actually has and the instructions it actually offers. Small and concrete, and the vocabulary the rest of the topic assumes.

  NPTEL: Computer Architecture and Organization · Course

• Timing and control

  How the machine keeps time and decides what happens next. Dry on its own, and the thing that makes the two control unit items below make sense.

• Hardwired control unit

  Control implemented in fixed logic: fast, and awkward to change. Half of the classic trade this topic is built around.

• Micro programmed control unit and control organization

  Control implemented as a small program in its own memory: slower, and changeable. The other half of the trade, and the same speed against flexibility axis that runs through the whole subject.

• The instruction cycle

  Fetch, decode, execute, and repeat. Follow one real instruction all the way round once and the abstractions above turn concrete.

• Program interrupt and the interrupt cycle

  What happens when something outside the program demands attention. Following the same cycle with an interrupt inserted is the exercise that makes it stick.

• Address sequencing

  How the control unit works out where its next micro instruction lives. It is the detail that makes the micro programmed approach a real design rather than a diagram.

• Micro instruction format

  The layout of a single micro instruction, which is where the size and speed of the control store is decided. It closes the loop on how the control unit is actually built.