Eric writes: The 432 architects went on to design a RISC processor that eliminated most of the drawbacks of the 432, but still supported object-oriented addressing, type safety, and memory safety, but using 33-bit word with one bit being the tag to differentiate Access Descriptors from data. This became the BiiN machine, which was unsuccessful. And we come full circle. One of the BiiN designers, John VanZandt (may have been from Intel) cut his teeth on the Burrough B6700 at UCSD (tags, descriptors, stack), and was one of the original implementors of UCSD Pascal. At school, he roomed with a FORTH/LISP/APL implementor (me). Small world, sometimes :) Stan