[TUHS] VFS prior to 1984

Adam Thornton athornton at gmail.com
Thu Jun 25 10:45:38 AEST 2020

On Wed, Jun 24, 2020 at 2:34 PM Greg A. Woods <woods at robohack.ca> wrote:

> As far as I can remember Multics didn't really have the concept of a
> "mount point".  All storage was single-level, i.e. segments (equivalent
> in some respects to inodes, but they are also actually the value of the
> segment register in the virtual memory hardware), and so files were
> either physically in memory or paged out on physical disk devices or
> similar, or even out on tape.  Where they actually resided was entirely
> and permanently hidden from the user.  What was called the "filesystem"
> was a form of database representing a hierarchical namespace which
> pointed at all the known segments (files) regardless of where they were
> actually stored.
Coming to it from a Unix perspective, it's like all storage (core, disk,
tape) is mmap()ed.

The segment-name database then is just an index relating symbolic names to
particular memory locations.

It all feels very upside-down to me, but that's probably because I grew up
in Unix and never actually used a Multics system until I emulated one with

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