Question

Arithmetic pipelining in computer architecture examples

Answer 1

As pipelining techniques developed, it became clear that pipelining the hardware used to implement complex arithmetic operations such as floating-point addition and multiplication could enhance performance. Floating-point addition,for example, consists of four distinct operations (exponent subtraction, mantissa shifting, mantissa addition, normalisation) which can be pipelined in a very straightforward manner.In a one-address system no benefit would be gained from pipelining arithmetic opreations: since one of the input operands to an addition operation in a one-address system is always the Accumulator, it cannot be used as an input to a subsequent operation until the current operation has finished. This implies that temporal overlap of two successive additions is not possible if the result must always pass through the Accumulator. For successful operationof a pipelined arithmetic unit each instruction must reference at least two and preferably three operands.

Answer 2

Pipelining is the process of accumulating instruction from the processor through a pipeline. It allows storing and executing instructions in an orderly process. It is also known as pipeline processing.

Pipelining is a technique where multiple instructions are overlapped during execution. Pipeline is divided into stages and these stages are connected with one another to form a pipe like structure. Instructions enter from one end and exit from another end.

Pipelining increases the overall instruction throughput.

In pipeline system, each segment consists of an input register followed by a combinational circuit. The register is used to hold data and combinational circuit performs operations on it. The output of combinational circuit is applied to the input register of the next segment.

For example: The input to the Floating Point Adder pipeline is X = A*2^aY = B*2^b
Here A and B are mantissas (significant digit of floating point numbers), while a and b are exponents.

The floating point addition and subtraction is done in 4 parts:

Compare the exponents.Align the mantissas.Add or subtract mantissasProduce the result.

Registers are used for storing the intermediate results between the above operations.