<jargon> A computer system or application program which
continues to be used because of the cost of replacing or
redesigning it and often despite its poor competitiveness and
compatibility with modern equivalents. The implication is
that the system is large, monolithic and difficult to modify.
If legacy software only runs on antiquated hardware the cost
of maintaining this may eventually outweigh the cost of
replacing both the software and hardware unless some form of
emulation or backward compatibility allows the software to
run on new hardware.
