Regiter Transfer Language | Register Transfer | Register Transfer micro-operation

Register Transfer Language

Micro-operation: A micro-operation is an elementary operation performed on the information stored in one or more registers. There are four types of microoperation: Register Transfer Micro-operation, Arithmetic Micro-operation, Logical Micro-operation, Shift Micro-operation.

The result of micro-operation may be stored in source or another register. Example of micro-operations are load, store, clear, shift, addition, count etc. A sequence of micro-operations is performed to complete one operation.

Let’s see example...

To add two numbers following micro-operation sequence has to be performed.

Step - 1:  Load first number in register 1

Step - 2: Load second number in register 2

Step - 3: Perform add micro-operation

Step - 4: Store the result in the destination register 3.

 

How we can we write above lengthy description in symbolic notation:

R1 ß A

R2 ß B

R3 ß R1 + R2

These symbolic notations are called a Register Transfer Language.

Here, T is used as a control variable. It is basically a Boolean variable having value 1 or 0. This statement indicates that the content of R1 are transferred to R2 only when T =1; otherwise transform operation is not performed. This means that if T=1 then R2 ßR1. (i.e., T: R2 ß R1)

Figure: Register Transfer

It is important to note that the clock is not included as a variable in the register transfer statement. It assumed that all transfer occurs during a clock edge transition either positive or negative.

If hardware permits two micro-operations can be executed at the same time. For example, exchanges the content of two registers, they perform R2ß R1 and R4ßR3 micro-operation simultaneously they are separated by comma in a statement.

T: R2 ß R1, R4ß R3.

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