Explain the control memory organisation and operation of the micro-programmed control unit with the help of a diagram of each

Sure, let’s break down the organization and operation of the micro-programmed control unit along with its control memory.

Control Memory Organization:

Control memory in a micro-programmed control unit stores microinstructions, which are sequences of microoperations that control the operation of the CPU. Each microinstruction corresponds to a specific control signal or sequence of control signals that control the CPU’s various components.

Control memory is typically implemented as a read-only memory (ROM) or programmable read-only memory (PROM). It consists of multiple rows, with each row containing the microinstructions for a specific control state or operation.

Diagram of Control Memory Organization:

+--------------+--------------+------------------+------------------+
| Control      | Control      | Control          | Control          |
| Memory Row 0 | Memory Row 1 | Memory Row 2    | Memory Row 3    |
+--------------+--------------+------------------+------------------+
| Microinstruction 0 | Microinstruction 1 | Microinstruction 2 | Microinstruction 3 |
+--------------+--------------+------------------+------------------+
| Microinstruction 4 | Microinstruction 5 | Microinstruction 6 | Microinstruction 7 |
+--------------+--------------+------------------+------------------+
| ...          | ...          | ...              | ...              |
+--------------+--------------+------------------+------------------+

Each row of the control memory represents a different control state or operation, and each column contains a microinstruction.

Operation of the Micro-Programmed Control Unit:

The micro-programmed control unit follows these steps during operation:

1. Fetch Microinstruction:

• The control unit fetches the current microinstruction from the control memory based on the current control state or operation.

1. Decode Microinstruction:

• The microinstruction is decoded to determine the control signals it represents.

1. Generate Control Signals:

• The control signals specified by the microinstruction are generated based on the decoding process.

1. Control CPU Components:

• The generated control signals are used to control the operation of various CPU components, such as the ALU, registers, memory, and input/output devices.

1. Update Control State:

• Depending on the current state and the microinstruction executed, the control unit updates the control state to proceed to the next microinstruction.

1. Repeat:

• Steps 1 to 5 are repeated for each instruction cycle or until the execution of the program is complete.

Diagram of Micro-Programmed Control Unit Operation:

                         +--------------+
                         | Control      |      
                         | Memory       |      
                         +--------------+
                               |
                               v
          +--------------+--------------+--------------+
          | Decode       | Generate     | Control CPU  |
          | Microinstr.  | Control      | Components   |
          +--------------+--------------+--------------+
                               |
                               v
                    +--------------+              
                    | Update       |                
                    | Control      |               
                    | State        |                 
                    +--------------+ 

Explanation:

• The control memory stores microinstructions that control the operation of the CPU.
• During operation, the microinstruction is fetched, decoded, and used to generate control signals.
• The generated control signals control the operation of CPU components.
• The control unit updates the control state based on the executed microinstruction to proceed to the next instruction.
• This process repeats for each instruction cycle, allowing the CPU to execute programs.