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* [TUHS] PDP 11/23 running UNIX version 6 at VCF Midwest!
@ 2021-12-19 17:25 Paul Ruizendaal
  2021-12-20 15:43 ` Dave Plonka
  0 siblings, 1 reply; 5+ messages in thread
From: Paul Ruizendaal @ 2021-12-19 17:25 UTC (permalink / raw)
  To: TUHS main list

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> While doing some end of year retrocomputing revisiting, I thought some
> of you might enjoy this - there is hope for the next generation(s)! ;)
> https://www.youtube.com/watch?v=_Zyng5Ob-e8 <https://www.youtube.com/watch?v=_Zyng5Ob-e8>


Thanks for that video link!

I noticed the bit at the end about V6 and  the occasional dropped character and that this was not a serial line issue. I have the same issue in my V6 port to the TI-990 and always assumed that it was a bug I introduced myself when hacking the tty driver.

Does anyone remember, was this a real life bug back in 6th edition back in the 1970’s? Maybe only showing at higher baud rates?

Paul


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^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [TUHS] PDP 11/23 running UNIX version 6 at VCF Midwest!
@ 2021-12-21 21:42 Noel Chiappa
  0 siblings, 0 replies; 5+ messages in thread
From: Noel Chiappa @ 2021-12-21 21:42 UTC (permalink / raw)
  To: tuhs; +Cc: jnc

    > From: Paul Ruizendaal

    > Does anyone remember, was this a real life bug back in 6th edition 

The 'V6' at MIT (actually, PWB1) never had an issue, but then again,
its TTY driver (here:

  http://ana-3.lcs.mit.edu/~jnc/tech/unix/mit/dmr/tty.c

if anyone wants to see it) was heavily re-written. But from the below,
it's almost certainlynothing to do with the TTY code...


    > From: Dave Plonka

    > one experiment we did was to redirection the bas(1)ic program's output
    > to a file and what we found was that (a) characters would still
    > sometimes be lost

Good test.

If you all want to chase this down (I can lend V6 expertise, if needed), I'd
say the first step is to work out whether it's the application, or the
system, losing the characters. To do that, I'd put a little bit of code in
write() to store a copy of data sent through that in a circular buffer, along
with tagging it with the writing process, etc.

Once you figure out where it's getting lost, then you can move on to
how/why.


    > From: Clem Cole

    > First Sixth Edition does not have support for either the 11/23

Yeah, but it's super-trivial to add /23 support to V6:

  http://gunkies.org/wiki/Running_UNIX_V6_on_an_-11/23

The only places where change is needed (no LKS register, no switch register,
and support for more than 256KB of main memory - and that one one can get by
without), it's hard to see how they could cause this problem.

    > One other thought, I'm pretty sure that Noel's V6+ system from MIT can
    > support a 23

No, we never ran than on a /23 BITD (no need, no mass storage); and I have
yet to bring the V6+ system up (although I have all the bits, and intend to,
at some point, to get its TCP/IP running). I've been using stock (well,
hacked a bit, in a number of ways - e.g. 8-bit serial line output) V6.

	Noel

^ permalink raw reply	[flat|nested] 5+ messages in thread
* [TUHS] PDP 11/23 running UNIX version 6 at VCF Midwest!
@ 2021-12-19  1:00 Dave Plonka
  0 siblings, 0 replies; 5+ messages in thread
From: Dave Plonka @ 2021-12-19  1:00 UTC (permalink / raw)
  To: tuhs

Hi folks!

While doing some end of year retrocomputing revisiting, I thought some
of you might enjoy this - there is hope for the next generation(s)! ;)
https://www.youtube.com/watch?v=_Zyng5Ob-e8

In this video I share my personal pick for "best"  demo at VCF
Midwest: Gavin's PDP 11/23 running UNIX Version 6!  We write and run a
simple BASIC program in Ken Thompson's bas(1), finding some quirks
with this (currently) entirely floppy-based system, possible having to
do with a glitch in disk I/O. (We discovered bas(1) uses a temporary
file as backing store.)

Filmed at the Vintage Computer Festival Midwest: VCF Midwest 16,
September 11, 2021
http://vcfmw.org/

Here's the source code to the simple program we wrote; you can also
run it on modern machines if you install a Research UNIX version using
SimH (pdp-11 simulator).

5 goto 30
10 for col = 1 arg(1)
12 prompt " "
14 next
20 print "Welcome to VCF Midwest!"
25 return
30 for x = 0 55
40 10(x)
50 next
60 for x = _56 _1
70 10(_x)
80 next

-- 
dave@plonka.us  http://www.cs.wisc.edu/~plonka/

^ permalink raw reply	[flat|nested] 5+ messages in thread

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Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-12-19 17:25 [TUHS] PDP 11/23 running UNIX version 6 at VCF Midwest! Paul Ruizendaal
2021-12-20 15:43 ` Dave Plonka
2021-12-20 16:30   ` Clem Cole
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2021-12-21 21:42 Noel Chiappa
2021-12-19  1:00 Dave Plonka

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