UMC's U5S/U5SX is significantly faster than the equivalent Intel/AMD 486SX.
A few interesting points are;
> It is not a "Clone" like an AMD and is more akin to a Cyrix in that it is a "Compatible" - UMC designed it themselves.
> UMC made some clever microcode optimizations, they somehow managed to make typical integer division complete in only 7 cycles opposed to the 40 that Intel/AMD required
> They added a decent 8KB Cache.
Which makes you wonder if the stupid Intel lawsuit was done out of brown trousers. Cowards. Imagine that though, largest semiconductor fab in Taiwan enters your industry with a product better than yours... A bad omen and it must be stopped! I wonder how different the world would be if UMC hadn't left. Interestingly the UMC processor sometimes detects as a Pentium under Windows 98 (Shady practices by Intel?).
Otherwise, AMD is a 1:1 copy of the Intel chip (other than the DX4 and X5, which may be different, I would have to do more research) whilst Cyrix brings up the rear - but don't forget that back in the day, Cyrix was incredibly cost effective.
Some strange kit back then, like the Winbond W89K for Socket 3, not instruction set compatible but I do wonder how it performed at similar tasks at least.
