hrubin@pop.stat.purdue.edu (Herman Rubin) (06/09/91)
.................. > > Herman Rubin asked: > > Why should it even be the case that the exponent and significand are in > > the same word? > > > > Because if they aren't every load or store will require 2 mem- > > ory references instead of 1 halving the speed in many cases. > Oh well, von Neumann advocated the use of scaled fixed point numbers. He > did not even consider floating point hardware. But I agree here, when we > have fp hardware it makes sense to have exponent and mantissa in the same > unit of information. This is not clear. On vector machines, weird methods have to be used to handle multiprecision (more than that which the hardware handles explicitly; IEEE double precision is not multiprecision) numbers or complex numbers if they are stored in adjacent units. It is first necessary to separate them for computation. Any floating point processor must start by separating the exponent and significand. -- Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399 Phone: (317)494-6054 hrubin@l.cc.purdue.edu (Internet, bitnet) {purdue,pur-ee}!l.cc!hrubin(UUCP)