Xenix 286?

On 2/22/2006 at 8:06 AM Brian Wheeler wrote: The wikipedia on memory management isn't too bad; contrast "segmentation" with "paging": http://en.wikipedia.org/wiki/Virtual_memory However, like a lot of computer-related stuff, these terms are evolutionary. The wiki would have you believe that special hardware is necessary for either paging or segmentation. Not true at all--JRT Pascal used segmentation and ran on a Z80 and I've worked on one BASIC implementation that paged from disk on an 8085. Similarly, my earlier comment was that a paging system could be implemented on a 286 if the page size was defined as the segment size limit--64K. Since the 286 doesn't offer offsets greater than 64K, one would still have to go through the nonsense of segment/offset calculation (why the 8086 never implemented a single instruction to compute a segment/offset from an existing segment-offset+displacement is beyond me), every distinct selector value represents a different page. To its credit, Windows 3.x did allocate large structures as a series of consecutively numbered selectors, so that a program could simply compute a new selector+offset value. Cheers, Chuck