P6 Binary Floating-Point Unit

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P6 Binary Floating-Point Unit
The floating point unit of the next generation PowerPC is detailed. It has been tested at over 5 GHz. The design supports an extremely aggressive cycle time of 13 FO4 using a technology independent measure. For most dependent instructions, its fused multiply-add dataflow has only 6 effective pipeline stages. This is nearly equivalent to its predecessor, the Power 5, even though its technology independent frequency has increased over 70%. Overall the frequency has improved over 100%. It achieves this high performance through aggressive feedback paths, circuit design and layout. The pipeline has 7 stages but data may be fed back to dependent operations prior to rounding and complete normalization. Division and square root algorithms are also described which take advantage of high-precision linear approximation hardware for obtaining a reciprocal or reciprocal square root approximation.
Son Dao Trong, Martin S. Schmookler, Eric M. Schwa
Added 02 Jun 2010
Updated 02 Jun 2010
Type Conference
Year 2007
Authors Son Dao Trong, Martin S. Schmookler, Eric M. Schwarz, Michael Kroener
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