> From: Johnny Billquist > While the pages are variable in length, each page starts at an 8K > virtual address boundary.
Which is another difference between PDP-11 'pages', and real pages as used on every other machine of the period which had virtual memory: normally, page sizes were small, ranging from 512 bytes to 1K words. No other machine was even _close_ to 8KB. In other machines, the page was the fundamental unit of memory allocation; on PDP-11's, that unit is the click (0100 bytes). > If you only had one page, and that page covered the full virtual > address space, then I would agree that it was a segment model. That's only true in the brain-damaged x86 model, in which 'segments' were added as a kludge to expand the address space. If you study _real_ segmented architecture machines, like the GE645, NS32K, etc you will discover that in them, a segment is a fixed-size chunk of the total (much larger) address space, and they start at fixed offsets in that space. A segment which is less than full-sized leaves a gap in the address space before the (fixed) start of the next segment. All of which sounds just like the 'pages' in the PDP-11... Noel