> From: Clem Cole
> Tops-20 or TENEX (aka Twin-Ex).
ISTR the nickname we used was 'TWENEX'?
BTW, the first 20 at MIT (MIT-XX) had a 'Dos Equis' label prominently stuck to
it... :-)
Noel
> From: Dave Horsfall
> I have a clear recollection that UNSW's driver (or was it Basser?) did
> not use interrupts .. but used the clock interrupt to empty the silos
> every so often. I'd check the source in the Unix Archive, but I don't
> remember which disk image it's in ... Can anyone confirm or deny this?
I found this one:
https://minnie.tuhs.org//cgi-bin/utree.pl?file=AUSAM/sys/dmr/dz.c
which seems to be the one you're rhinking of, or close to it.
It actually does use interrupts, on both sides - sort of. On the input side,
it uses the 'silo alarm', which interrupts when the input buffer has 16
characters in it. This has the same issue as the silo on the DH11 - if there
are less characters than that waiting, the host never gets an interrupt. Which
may be why it does the timer-based input check also?
The output side is entirely interrupt driven; it _does_ reduce the number of
interrupts by checking _every_ output line (on every DZ11 in the machine) to
see if that line's ready for a character when it gets any output interrupt,
which will definitely seriously reduce the number of output interrupts - but
even then, if _one_ line is going flat out, that's still 1000 interrupts per
second.
Noel
Arthur Krewat:
On 5/29/2018 4:11 PM, Dan Cross wrote:
> "I don't always use computers, but when I do, I prefer PDP-10s."
>
> B B B B - Dan C.
Write-in for President in 2020.
===
Only if he's Not Insane.
Norman Wilson
Toronto ON
Long ago, at Caltech, I ran a VAX which had a mix of DZ11s and
Able DH/DMs. The latter were indeed much more pleasant, both
because of their DMA output and their fuller modem control.
For the DZ11s we used a scheme that originated somewhere in
the USG-UNIX world: output was handled through a KMC11.
Output interrupts were disablled on the DZ; a program
running in the KMC fetched output data with DMA, then
spoon-fed it into the DZ, polling the status register
to see when it was OK to send more, then sending an
interrupt to the host when the entire data block had
been sent.
The KMC, for those fortunate enough not to have programmed
it, has a very simple processor sort of on the level of
microcode. It has a few specialized registers and a
simple instruction set which I don't think had all four
of the usual arithmetic ops. I had to debug the KMC
program so I had to learn about it.
When I moved to Bell Labs a few years later, we didn't
need the KMC to drive serial lines--Dennis's stream I/O
code was able to do that smoothly enough, even with DZ11s
on a VAX-11/750 (and without any assembly-language help
either!). But my experience with the KMC was useful
anyway: we used them as protocol-offload processors for
Datakit, and that code needed occasional debugging and
tweaking too. Bill Marshall had looked after that stuff
in the past, but was happy to have someone else who
wasn't scared of it.
Norman Wilson
Toronto ON
> From: Paul Winalski
> DZ11s ... the controller had no buffer
Huh? The DZ11 did have an input buffer. (See the 'terminals and communications
handbook', 1978-79 edition, page 2-238: "As each character is received ...
the data bits are placed ... in a .. 64-word deep first-in/first-out hardware
buffer, called a 'silo'.")
Or did you mean output:
> if you were doing timesharing it could bring the CPU to its knees in
> short order
The thing that killed an OS was the fact that output was programmed I/O, a
character at a time; using interrupt-driven operation, it took an interrupt
per character. So for a 9600 baud line, 9 bits/character (1 start + 7 data + 1
stop - depending on the line configuration), that's about 1000 characters per
second -> 1000 interrupts per second.
The DH11 used DMA for output, and was much easier on the machine.
Noel
Lars Brinkhoff <lars(a)nocrew.org> reports on Mon, 28 May 2018 10:31:56 +0000:
>> But apparently the inspiration came from VMS:
>> http://web.archive.org/web/20170527120123/http://www.unixtop.org:80/about.s…
That link contains the statement
>> The first version of top was completed in the early part of 1984.
However, on TOPS-20, which was developed several years before VMS, but
still from the same corporation, we had the sysdpy utility which
produced a similar display as top does.
>From my source archives, I find in score/4-utilities/sysdpy.mac the
ending comments:
;462 - DON'T DO A RLJFN AFTER A CLOSF IN NEWDPY
;<4.UTILITIES>SYSDPY.MAC.58, 2-Jun-79 14:15:54, EDIT BY DBELL
;461 - START USING STANDARD TOPS-20 EDIT HISTORY CONVENTIONS, AND
; REMOVE OLD EDIT HISTORY.
...
;COPYRIGHT (C) 1976,1977,1978,1979 BY DIGITAL EQUIPMENT \
CORPORATION, MAYNARD, MASS.
I therefore expect that there was 460-entry list of log messages that
predated 2-Jun-1979, and likely went back a few years. Two other
versions of sysdpy.mac in my archives have also dropped log messages
before 461.
Even before TOPS-20, on the CDC 6400 SCOPE operating system, there was
a similar tool (whose name I no longer recall) that gave a
continuously updated display of system-wide process activity. That was
available in at least late 1973.
I suspect that top-like displays were added to most other interactive
operating systems, as soon as screen terminals made updates convenient
without wasting console paper. One of the first questions likely to
be asked by interactive users is "what is my job doing?".
In a TOPS-20 terminal window, you could type Ctl-T to get a one-line
status report for the job that was currently running from your
terminal. For many users, that was preferable to sysdpy, and it was
heavily used.
-------------------------------------------------------------------------------
- Nelson H. F. Beebe Tel: +1 801 581 5254 -
- University of Utah FAX: +1 801 581 4148 -
- Department of Mathematics, 110 LCB Internet e-mail: beebe(a)math.utah.edu -
- 155 S 1400 E RM 233 beebe(a)acm.org beebe(a)computer.org -
- Salt Lake City, UT 84112-0090, USA URL: http://www.math.utah.edu/~beebe/ -
-------------------------------------------------------------------------------
> From: Lars Brinkhoff
> I'm surprised it appeared that late. Were there any other versions or
> similar Unix programs before that?
The MIT ~PWB1 system had a thing called 'dpy', I think written at MIT based on
'ps' (and no doubt inspired by ITS' PEEK), which had similar functionality.
Seems like it never escaped, though. Man page and source here:
http://ana-3.lcs.mit.edu/~jnc/tech/unix/man1/dpy.1http://ana-3.lcs.mit.edu/~jnc/tech/unix/s1/dpy.c
The top of my hard-copy man page says 'November 1977', but I suspect it dates
back further than that.
Noel
On this day in 1936, notable mathematician Alan Turing submitted his
thesis "On Computable Numbers", thereby laying the foundations for today's
computers.
Sigh; if only he hadn't eaten that apple... And we'll never know whether
it was murder or suicide.
-- Dave
> I still find pic really useful ... > I don't know of any other tool
that lets you do drawings like that
Unix had "ideal", a remarkable language by Chris Van Wyk, based on complex
numbers and capable of some constraint solving. Its code seemed to be
lost but can now be found in one of the online v10 repositories. I've
been meaning to try to resurrect it. If anyone has already done so,
I'd love to hear about it.
I, too, have some pic macros, though no big coherent packages, to do
things like polar coordinates and solving for the intersection of lines
and circles. I have even in extremis made filled triangles with scripts
that massage PostScript by deleting corners of filled rectangles. Then
from triangles you can, with patience, make polygons.
Doug
A worthy question.
---------- Forwarded message ----------
From: Richard Haight <dickhaight(a)gmail.com>
Date: Thu, May 24, 2018 at 2:53 PM
Subject: unix
To: jpl.jpl(a)gmail.com
Recently I was asked if I still had a spare deck of the Unix-25 cards.
Hadn’t thought of them in years. But it made me realize that 2019 will be
the 50th. Is anyone working on something to mark the anniversary?
