9 Apr
2022
9 Apr
'22
9:28 p.m.
At Fri, 8 Apr 2022 17:34:27 -0600, Andrew Warkentin <andreww591(a)gmail.com> wrote:
Subject: Re: [TUHS] Interesting commentary on Unix from Multicians.
I think it's useful to have both I/O and memory views for files.
Things like commands that work equally well whether stdout is a disk
file or something like a pipe wouldn't work so well in a system where
disk files can only be accessed through a memory-like interface.
However, I guess the I/O interface could just be implemented with
library functions rather than real I/O syscalls for disk-like files.
I/O is good for I/O of course (e.g. to devices, like terminals and
printers and such), and if you can "attach" that I/O to a segment, or to
another program's I/O, all the better:
https://multicians.org/myths.html#nofile
(One big complication forced by hardware limitations of the day was
rather limited file (i.e. segment) size, and thus Multics developers
invented multi-segment files, and as mentioned in that link, stream
access to them was often through the I/O mechanism, but of course this
was a simulation done by copying (I think) data from a mapped segment of
the file to a buffer in a heap segment.)
--
Greg A. Woods <gwoods(a)acm.org>
Kelowna, BC +1 250 762-7675 RoboHack <woods(a)robohack.ca>
Planix, Inc. <woods(a)planix.com> Avoncote Farms <woods(a)avoncote.ca>