I have thought, on occasion, about simulating a segmented machine on a non-segmented machine, i.e. one with large unidirectional addresses (segmented being a bi-directionally addressed machine) - in fact, I think it was in the context of the VAX that I went through this mentally. I don't recall any more the exact outcome of my mental design processes (it was a _long_ time ago), but I have this vague recollection that it could sort of work, but that it would be ugly (as in, the compiler would have to simulate cross-segment pointers, etc - they don't look just like normal pointers as there has to be provision for binding them when first used, etc). Large unidirectional machines do have one advantage, which is that the canonical flaw of single-level-storage on a segmented machine is that really large objects don't fit in a single segment, unless you have ridiculously large addresses (e.g. 80 bit). When simulating segments on a unidirectional machine, one can of course make any individual segment as large as one likes - up to the total size of the unidirctional machine's address space. Noel