Skip to main content

Microprogrammed Control Unit

 Microprogrammed Control Unit (MCU) is a Control Unit of a Computer. The  design of MCU is Program based. Such a Control Unit is a programmed one. The Programming activity that is deployed is called  Microprogramming. A Microprogram is designed performing Microprogramming action.

In fact, Microprogramming is the task undertaken for designing and building  the Control Unit of a Computer . Such a Control Unit is called Microprogrammed Control Unit (MCU). For building the MCU, an additional memory called Microprogram Store is used.

MCU is responsible for controlling the activities inside a Computer System. Generally, the directives issued to the Computer System at the Hardware level are controlled and coordinated by the MCU. Hardware level activities performed using MCU affect data processing facilitated by a Computer.

MCU performs like a conventional Control Unit. The difference is that, instead of being hardwired, MCU is designed to be programmed (or Microprogrammed to be precise).

In a Computer Program, we have instructions. In the same way, a Microprogram is composed of microinstructions. Several microinstructions are required to execute a machine instruction (an instruction given to a Computer). 

A Microinstruction performs several Control Functions. These Control Functions are Microoperations. A Microperation is signified by a binary digit(bit).


The instructions that we normally encounter are machine instructions. Machine instructions are used to instruct the machines, or Computers. 

Microinstructions are used to perform control activities. Execution of an instruction given to a Computer is carried out by several Microinstructions.

The activities that are related to Microprogrammed Control impact the Computer System very effectively. The effectiveness of control action directed by the MCU is a decisive one.

Let us detail the structure of a Microinstruction. Microinstruction is  composed of several binary digits ( bits ). A Microinstruction, being a multi bit entity, performs several  Control Functions. One bit means, one Control Function. So, several bits mean several Control Functions. Control Functions are visible in the form of Microperations.

Yes, the structural constituents of Microinstructions are binary digits. The bits are, of course, indivisibly small. 

There are several examples of MCU driven  Microoperations. Microoperations have to be ordered, or sequenced.

Execution of Microoperations is sequenced by Microprogram Sequencer. Microprogram Sequencer is associated with the Microprogram Store. Such Sequencer can be compared to Program Counter. We note that Program Counter is a part of Computer Architecture.

We can have three Microperations for a Computer Instruction that requires transfer of data from CPU to the Main Memory of a Computer. Let us suppose that we require such a transfer.

The Microoperations that are performed see the following activities:

( 1 ) A Microoperation may transfer the contents of the Program Counter to Memory Address Register (MAR).

( 2 ) Incrementing the contents of Program Counter may require a Microperation. 

( 3 ) Performing the transfer of the contents of the Accumulator to the Memory Buffer Register (MBR) highlights the execution of a Microperation.

////////////////////////////////////////////

Computer Instruction

             ^

             |

MICROPROGRAM

             ^

             |

MICROINSTRUCTIONS 

             ^

             |

MICROINSTRUCTION        

            ^

            |

          BITS

            ^

            |

          BIT

            ^

            |

CONTROL FUNCTION

            ^

            |

Microoperation 

////////////////////////////////////////

Fig: Microprogram

(Structural & Functional Details Given) 

___________________________

___________________________

Goodbye!

Have a great day!!

___________________________

___________________________


Labels:

Comments

Post a Comment

Popular posts from this blog

Local-Area Networks

Local-Area Networks ( LANs ) are restricted to a small area. Such Networks may be established within a building. Computers that are part of Local-Area Networks are Personal Computers ( PCs ) or microcomputers. These Computers are connected to each other. Simple communication lines connect these Pers Networks bring people together. When people join  hands teamwork becomes possible. The structural composition of LANs simplifies teamwork. In other words, LAN hardware supports teams having similar processing requirements. LAN Computers readily support personalization of tasks allocated to professionals.  Office staff can work together and share information. This improves the efficiency of the entire workforce. It has been noted that here all the Networked Computers are Personal Computers. They are of equal capacity. Mostly LAN users have similar tasks. If situations allow, a user is independent to access any Computer to serve his purpose. LAN users can exercise the option of secu...
Post a Comment
Read more

Computers - An Introduction

Computers are man made machines. They are made to work very fast. Working fast they can solve  big and small problems.  Modern science has given us these computers. They are very popular. Computers affect and change lives. They keep us happy.The happiness grows. Computers are quick and smart. Great problem solvers and simplifiers are our computers. They can do our work without stopping. Focus is on doing only what is needed. Not needed, not done.  Computers are  life-less servants. They cannot think or make decisions on their own. They are empowered to work. They are given each and every thing so that they carry out our orders. Orders are respected by computers. The manner in which computers work is wholly dependent on man.  The quality of service provided by computers is remarkable. They are loved by human beings. Computers are known for smart and quick service. Computers do not give wrong results. Correct answers are always given. Questions which are difficult...
Post a Comment
Read more

Euclid's Algorithm

The Greatest Common Divisor ( GCD ) of  two numbers is a number. The number ( GCD ) causes division of the two numbers. This number ( GCD ) is the greatest number that is possible. This divisor partially forms the two numbers. Adding  the divisor successively may result in formation of the two numbers. One can note that when the divisor is the greatest, the division of the dividend is the sharpest. The division operation is very effective. When the Greatest Common Divisor of two numbers is considered, we think of a number that can cause division of both the numbers. Here the two numbers are unequal. The Greatest Common Divisor causes divisions of the two numbers differently. This is clear from the two different quotient values.  The GCD value is very interesting to note. It relates very well with the two numbers. The GCD of two even numbers is also an even number. The GCD of two odd numbers is an odd number. So, we can say that GCD is an abstraction of the two numbers in ...
1 comment
Read more