What are the advantages and disadvantages ofmicroprogrammed control unit? Explain the Wilkes’smicroprogrammed control unit.

The advantages and disadvantages of a microprogrammed control unit can be explained as follows:

Advantages:

1. Flexibility: A microprogrammed control unit allows for easy modification and customization of the control unit's behavior. This flexibility is particularly useful in complex systems where frequent changes or updates are required.
2. Simplified Design: Microprogramming allows for a more simplified and modular design of the control unit. This can lead to easier development, debugging, and maintenance of the control unit.
3. Improved Performance: Microprogramming can optimize the execution of instructions by using microinstructions that are specifically tailored for each instruction. This can result in improved performance and efficiency of the control unit.

Disadvantages:

1. Increased Complexity: Microprogramming adds an additional layer of complexity to the control unit design. This can make the overall system more difficult to understand and debug.
2. Slower Execution: The use of microinstructions can introduce additional overhead and result in slower execution compared to hardwired control units. This can be a disadvantage in systems that require high-speed processing.
3. Limited Parallelism: Microprogramming typically follows a sequential execution model, which limits the ability to exploit parallelism in the control unit. This can be a disadvantage in systems that require high levels of parallel processing.

Now, let's explain Wilkes's microprogrammed control unit:

Wilkes's microprogrammed control unit is a specific implementation of a microprogrammed control unit developed by Maurice Wilkes in the 1950s. It was used in the EDSAC 2 computer, which was one of the earliest stored-program computers.

In Wilkes's microprogrammed control unit, the control logic of the computer is implemented using microinstructions stored in a control memory. These microinstructions control the sequencing and execution of instructions in the computer.

The microinstructions in Wilkes's microprogrammed control unit are stored in a control memory, which is separate from the main memory of the computer. This allows for easy modification and customization of the control unit's behavior without affecting the main memory.

Wilkes's microprogrammed control unit offered several advantages, including flexibility, simplified design, and improved performance. It allowed for easy modification of the control unit's behavior, simplified the design of the control unit, and optimized the execution of instructions.

However, it also had some disadvantages, such as increased complexity, slower execution, and limited parallelism. The additional complexity of microprogramming made the system more difficult to understand and debug. The use of microinstructions introduced overhead and resulted in slower execution compared to hardwired control units. Additionally, the sequential execution model of microprogramming limited the ability to exploit parallelism in the control unit.

Overall, Wilkes's microprogrammed control unit was a significant development in the early days of computer architecture and played a crucial role in the advancement of computer systems.