From: guy@Auspex.COM (Guy Harris)
Newsgroups: comp.arch
Subject: Re: multiuser systems (was Re: IBM AS/400 is the world's slowest..)
Date: 2 Jan 93 04:25:55 GMT
Organization: Auspex Systems, Santa Clara

>People who suffered timeshared systems in the 70's often refuse to
>believe any of this unless they have direct experience of the
>benefits.

I suspect the people who suffered timeshared systems back then suffered
from having a timesharing system capable of supporting N people
comfortably, but having M > N (perhaps M >> N) people using it
regularly.

Is it that at least some of the resources that were in too scarce supply
back then - CPU and memory - are now in much more plentiful supply, so
that you're less likely to have an overloaded time-sharing system? 

(Yes, I remember early-'80s timesharing systems.  I've *no* desire to
use a timeshared system that can't, for example, give quick response to
keystrokes in editors such as Frame Maker, even if other folks are doing
compiles, running their own sessions with Frame or 1-2-3 or whatever.)

>The strength of this argument is not undermined by the horrors of X:
>at least it provides graphical interaction over a network.

And not all such systems (central compute and file servers, desktop
graphics machines that aren't expected to do all the compute work
themselves) use X; see, for example, Bell Labs's Plan 9.

Rob Pike has made many of the same arguments (lower cost for desktop
machines, ability to upgrade the central machine's CPU power instead of
upgrading all the desktop machines) for the Plan 9 system (although,
Rob's tendency, at least at one point, to refer to the desktop machines
as "terminals" nonwithstanding, they're actually diskless workstations,
running essentially the same OS as the compute servers, and capable of
running applications, although they generally have less CPU power and
probably less memory than the compute servers).

The Plan 9 model is actually a bit different from the "dumb terminal"
model, even the "dumb X terminal" model, as applications that don't
consume *huge* amounts of CPU, and that are quite interactive - e.g.,
text editors (even ones such as Frame; they probably consume more CPU
than "vi", but probably not as much as Verilog...), spreadsheets, blah
blah blah, can be run on the desktop machine.

Applications requiring more CPU or memory, or requiring a tighter
connection to the file server (the compute servers and file servers are
joined by higher-speed links than are the desktop computers and file
servers), but not requiring quick response to keystrokes or mouse
motions are probably run on the compute server.  (Graphical applications
that talk directly to a window, and get keyboard and mouse events
directly, can be run either on the compute server or the desktop
computer; the window system is one that runs over a network.)

(If you want to debate the merits of Plan 9, debate them with Rob Pike
or Ken Thompson, not with me.  I've never used it, I've just heard about
it and read some papers on it.  I'm pretty much just reciting its
creator's views, as I understand them; I've not enough information to
agree *or* disagree with them, at this point....)
Newsgroups: comp.arch