Register Transfer language

It is a symbolic notation used to repress the micro operations transfer among registers.It is an intermediate representation that is very close to assembly language.RTL describes how the micro operations are done in between the registers and transfer of result of operation to the same or other register.The operation executed on the data store in registers are called micro-operations.

Register Transfer

The data transfered from one register to another register is represented in symbolic notation by replacement operator is called register transfer.

Replacement Operator : 

In the statement, R2 <- R1, <- acts as a replacement operator. This statement defines the transfer of content of register R1 into register R2.

General way of representing a register is by the name of the register inclosed in a rectangular box 

The numbering of bits in a register can be marked on the top of the box . 

Basic Symbols of RTL

• ( )   denotes a part of register                       Ex:R(0-7)
• <-   denotes a transfer of data                      Ex:R1<-R2
•  ,     seperation of 2 micro operations          Ex:R1 <- R2R2 <- R1 
•  :      Denotes conditional operations                    Ex:P : R2 <- R1  if P=1

Register Transfer Operations

The operations performed on the data stored in the registers is refered as register transfer operations.

1.Simple Transfer – R2 <- R1

The content of R1 is transfered from R1 to R2

2.Conditional Transfer

It indicates that if P=1, then the content of R1 is transferred to R2. It is a unidirectional operation. 

3.Simultaneous Operations 

If 2 or more operations are to occur simultaneously then they are separated with comma (,).If the control function P=1, then load the content of R1 into R2 and at the same clock load the content of R2 into R1.