The Free On-line Dictionary of Computing (30 December 2018):
(6x86) IBM and Cyrix's sixth-generation,
64-bit 80x86-compatible microprocessor. The 6x86 combines
aspects of both RISC and CISC. It has a superscalar,
superpipelined core, and performs register renaming,
speculative execution, out-of-order completion, and data
dependency removal. It has a 16-kilobyte primary cache and
is socket-compatible with the Pentium P54C. It has four
performance levels: PR 120+, PR 150+, PR 166+ and PR 200+.
The chip was designed by Cyrix and is manufactured by IBM.
The architecture of the 6x86 is more advanced than that of the
Pentium, incorporating some of the features of Intel's
Pentium Pro. At a given clock rate it executes most code
more quickly than a Pentium would. However, its FPU is
considerably less efficient than Intel's.