18.1.2. Unit Objectives

At this unit you will be able to associate the control signals by looking at the control steps of each instruction that is the micro instruction and the processor and to implement the control signal by digital logic circuit.

In this unit, you'll learn how to identify control signals connected with each micro instruction during processing in a CPU. This involves examining the sequence of steps in instructions—like fetching, decoding, and executing—and understanding which control signals are active at any given point. Additionally, you will also get the skills to create digital logic circuits that implement these control signals, an essential part of designing hardware that can perform these instructions.

Think of a traffic light system that controls the flow of cars based on the movements required at an intersection. Just as the traffic lights change signals to guide cars (red for stop, green for go), control signals in the CPU guide the actions of various components based on what instructions are being executed. Learning to associate these signals with step instructions is similar to understanding when to change the traffic light based on traffic flow.

For this basic design of finite state machine we will not be covering in this unit; because it corresponds to your digital design fundamentals. So, if some truth table is given so, how you design a finite state machine in terms of gates and flip flops that you have to recollect that.

This objective relates to designing a finite state machine (FSM) from a truth table. Although this specific design process won't be covered in-depth in this unit, the essential idea revolves around understanding how to create an FSM using logical gates and flip-flops. An FSM is crucial in the hardware implementation of control units as it manages transitions between different states to execute instructions correctly based on control signals.

Consider a simple game of 'Simon Says.' The game has rules to follow, and you move to a next step only after performing an action correctly (like standing up or clapping). Each player must be aware of their current state (sitting or standing) and what the next command is. Designing a finite state machine is similar in that it determines the current state and what actions or transitions occur next based on incoming signals.

And finally, there is a design objective design the design issues and implementation of the control unit. So, if I give you a macro instruction you will be able to design the finite state machine based controller for that, that is what is the idea.

The control unit design objectives focus on how you can take a macro instruction (which is a broader action performed by the CPU) and effectively design a finite state machine (FSM) to control the specifics of this instruction. You will learn to identify design issues that may arise and how to implement solutions through logical circuit design, ensuring that the control unit executes operations smoothly.

Imagine planning a powerful concert where multiple musicians play together harmoniously. You need a conductor (control unit) to guide when each musician plays their part (macro instruction). Designing a control unit is like setting up a precise schedule for when each musician should come in, ensuring that all parts come together in an orchestrated manner while avoiding confusion or miscommunication.

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