PM> Several people in this thread have mentioned that wide registers

PM> are needed for big number-crunching applications. True, but the

PM> registers in that case are the floating point registers, which in

PM> the 80x86 architecture are separate from the main processor

PM> registers. The floating point registers in these processors have

PM> always been 80 bits wide, and probably always will be.

AS> IIRC, the IEEE standard on floating point maths has something to

AS> say about the required precision and may therefore have a bearing

AS> on this.

I don't have a copy of IEEE 754 to hand, but people have stated that 80 bits

is simply the _minimum_ size for extended precision floating point, single

precision and double precision being more strictly defined.