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Aucbvax.2076 fa.works utzoo!duke!decvax!ucbvax!Deutsch@PARC-MAXC Sat Jul 4 09:30:03 1981 Re: Addressing and File Accessing I must be missing something. Barns wishes for "an n-bit number which is absolute for the whole workstation". Isn't a reasonable-size conventional virtual address a solution to this problem, provided that the operating/language system doesn't allow you to fabricate addresses? That's the only sense in which the Lisp Machine solves the problem, and it only does it by virtue of NOT having any local capability for named files. The LM doesn't provide any facilities that replace a local file system, either, e.g. there are no tools in the system for constructing and manipulating directories of variables. Furthermore, the LM would be helpless without the presence somewhere in the network of some very conventional file systems which handle messy questions like space accounting, periodic backup, user authentication, etc.

Of course, if you want local objects to be remotely accessible, then you do need something much more like capabilities. Given that mainframes (processor + memory) are so cheap these days, compared to the cost of a reasonable-size disk, I'm more inclined to favor putting all potentially sharable objects on a separate server mainframe and let workstations either cache them on their local disks or get them over the network whenever they need to. This requires some architectural changes in the world to make that network access comparable in speed to, say, something between a cache miss and a bubble memory access, as opposed to a disk access.

To the best of my knowledge, Star, like the research machines (Dolphin and Dorado), has a conventional paged address space; the Star OS provides for mapping full or partial files into this space, like Tenex or Multics. The OS happens to be optimized for mapping sequential runs of pages of a single file into contiguous virtual pages, but that is an optimization only.

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