Weitek 4167 coprocessors
The 4167 is a memory-mapped coprocessor that has the same architecture as the 3167; it is designed to provide 486-based systems with the highest floating-point performance available. It executes coprocessor instructions at three to four times the speed of the Weitek 3167. Although it is up to 80% faster than the Intel 486 in some benchmarks, the performance advantage for real application is probably more like 10%. The introduction of the 486DX2 processors has more or less obliterated the need for a Weitek 4167, since the DX2 CPUs provide the same performance as the Weitek, as well as the additional features the 80x87 architecture has that the Weitek does not.
The Weitek 4167 is packaged in a 142-pin PGA package that is only slightly smaller than the 486's package. At 25MHz, it has a maximum power consumption of 2500mW.