rapidcad

from The Free On-line Dictionary of Computing (8 July 2008)

RapidCAD

   <processor> A specially packaged {Intel 486DX} and a dummy
   {floating point unit} (FPU) designed as pin-compatible
   replacements for an {Intel 80386} processor and {80387} FPU.
   Since the DX variant has a working on-chip FPU, a dummy FPU
   package is supplied to go in the {387} FPU socket.

   (1995-05-10)