28-01-2011, 02:40 PM
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Definition and Characteristics
Superscalar processing is the ability to initiate multiple instructions during the same clock cycle.
A typical Superscalar processor fetches and decodes the incoming instruction stream several instructions at a time.
Superscalar architecture exploit the potential of ILP(Instruction Level Parallelism).
Uninterrupted stream of instructions
The outcomes of conditional branch instructions are usually predicted in advance to ensure uninterrupted stream of instructions
Instructions are initiated for execution in parallel based on the availability of operand data, rather than their original program sequence. This is referred to as dynamic instruction scheduling.
Upon completion instruction results are resequenced in the original order.
CONCLUSION
It thereby allows faster CPU throughput than would otherwise be possible at the same clock rate.
All general-purpose CPUs developed since about 1998 are superscalar.
The major problem of executing multiple instructions in a scalar program is the handling of data dependencies. If data dependencies are not effectively handled, it is difficult to achieve an execution rate of more than one instruction per clock cycle.