🚀 go-pugleaf

In article <38990@peregrine.peregrine.com> robert@peregrine.peregrine.com (Robert Young) writes:
>I am looking for a SLIP package to run on a Sequent machine ( DYNIX 3.0.12).

It's out there somewhere. I'd be curious if the versions that have been done
for Dynix are symmetrized, or single threaded. The big headache on any of
these parallel UNIX systems is symmetrizing the stock drivers, and it's often
easier to just not bother. (The original Lachman NFS port was single threaded,
for example.) Of course, for the vendor to actually *ship* a product, it has
to be symmetrized; that's one reason this kind of thing takes longer coming
from the vendor than it does to pluck it off the net.

>	a) NCD-16 Terminals
>	b) A workstaion running an X-Windows Server (PCXVIEW for example)
>	c) SLIP

Apples and oranges. You have at least three issues floating here:

	X Server terminal 	vs.	Workstation with X server software
and:
	Ethernet		vs.	SLIP
and:
	PC Word Processing	vs.	Host-based Word Processing

The terminal vs. workstation issue is pretty blurry; an NCD is a much faster
piece of iron than a PC running an X Server, for example, but less versatile.
(Personally I'd take the NCD; for the money you get a much better display.)
And of course the original X server is a Sun Workstation. But you might not
want X at all; I know a lot of people who are happy with Microsoft Windows
and PC/NFS.

SLIP vs. Ethernet is a little more clear-cut, but hardly obvious. Most of the
X Servers I've seen -- either plug-and-go terminals or software packages --
will talk either one. SLIP is lots cheaper; you only need an RS-232 line. But
it has some serious problems:

- SLIP is slower in the first place. Unless Sequent has replaced the Systech
  mux boards, you are pretty much limited to 9600 baud; with TCP/IP overhead,
  it will be visably slower than a direct 9600 baud tty line. You won't care
  for text; you *will* care for graphics or WYSIWYG word processors.

- The 4.2BSD networking code in Dynix -- and the 4.3BSD code, too -- is tuned
  for very fast networks. We (Pyramid) have been running SLIP over various
  interfaces for a while now, and have tried a large collection of different
  X Servers over SLIP, at speeds from 4800 baud to 38.4K. The results were
  equivocal at best. Timeouts and TCP retransmissions occur at awkwards times,
  causing ugly delays as the protocol trips over itself. And it varied from
  terminal to terminal; some worked better at slower speeds, others at higher.

  The solution is Van Jacobson's intelligent timeout enhancements that were
  added to the 4.3BSD-tahoe release. I've talked to people who have seen this
  at work on a Sun, and it provides much smoother -- though not ideal -- X
  Server operation. But as far as I know, the only vendor shipping this today
  is Sun. And ironically, Sun doesn't support SLIP.

- One of the biggest wins of X Server on Ethernet is that you aren't tied to
  a single host. If you're main machine dies, no sweat; log into another, and
  keep going on something else. With SLIP, you are as tied to the host as if
  you were on a direct RS-232 link -- because, in fact, you are.

- With Ethernet, you need to only run one length of cable. With SLIP, you
  have to run individual RS-232 lines everywhere, just like for terminals.

On the whole, I'm not very happy with low-speed SLIP as a network solution
*today*. In the near future, that will change dramatically; SLIP is rapidly
becoming a very important link-level protocol (to its creator's considerable
surprise and amusement).

>Is it better to just use an XWINDOWS terminal and run the Word Processor
>right out of the Sequent?

As opposed to what? It sounds to me like you haven't really thought through
what you are trying to do here. I can run PageMaker on a PC using PC/NFS to
link into the host system, running over Ethernet or SLIP. In that case, all
the computation is done on the PC, but the storage is on the host. PC/NFS
takes care of the remote login that way, too. Or I can run FrameMaker on my
host, using an X Server terminal or a PC with X Server software; all the
computation is done on the host, and the terminal (or PC) just handles the
graphics primitives.

Which to chose depends on far more factors than we can go into here. The X
Server is going to be faster, in all probability. A PC allows you to do work
locally.  An X terminal like the NCD gives a much more reabable display for
the money. If you are already doing all your other work on the big host, then
it would be silly to split your work off onto a PC. And so on.

<csg>