Decimal Arithmetic FAQ Part 4 – Arithmetic Specification
Questions It is quite possible for decimal arithmetic to be
normalized, even if the encoding (representation) of numbers is
not. A floating-point unit can easily offer both normalized and
unnormalized arithmetic, either under the control of a context
flag or by a specific ‘normalize’ instruction (the latter being
especially appropriate in a RISC design). However, for decimal
arithmetic, intended as a tool for human use, the choice of
unnormalized arithmetic is dictated by the need to mirror manual
calculations and other human conventions. A normalized (non-
redundant) arithmetic is suitable for purely mathematical
calculations, but is inadequate for many other applications.
Note that the unnormalized arithmetic gives exactly the same
mathematical value for every result as normalized arithmetic
would, but has the following additional advantages. A normalized
arithmetic cannot duplicate the results of unnormalized
arithmetic and so these existing software