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From: Dave Plonka <>
To: Paul Ruizendaal <>
Cc: TUHS main list <>
Subject: Re: [TUHS] PDP 11/23 running UNIX version 6 at VCF Midwest!
Date: Mon, 20 Dec 2021 09:43:56 -0600	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Hi Paul

We talked about this a bit more in the comments on the video, with
Gavin doing some experiment afterwards.

While at the show, 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 (which is how we determined
it's not due to a serial communications, directly and (b) the dropped
characters would coalesce together into a small run.

Gavin's speculation at the time was that the floppy driver
interfered/interrupted the bas' output somehow, since we noticed there
was also disk activity coinciding roughly in time with a bout of
dropped characters.

What is unusual about Gavin's machine (at the time of this video) is
that everything was on floppies - including root, tmp, etc. because he
did not have a functioning fixed disk yet. It may be a configuration
that was rarely used, e.g., scratch space for bas on floppy. (We found
bas seems to read the source code from the file system even at

Any insights welcome - esp. if you can put them in the comments there.


On Sun, Dec 19, 2021 at 11:25 AM Paul Ruizendaal <> wrote:
> While doing some end of year retrocomputing revisiting, I thought some
> of you might enjoy this - there is hope for the next generation(s)! ;)
> 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


  reply	other threads:[~2021-12-20 15:44 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-19 17:25 Paul Ruizendaal
2021-12-20 15:43 ` Dave Plonka [this message]
2021-12-20 16:30   ` Clem Cole
  -- strict thread matches above, loose matches on Subject: below --
2021-12-21 21:42 Noel Chiappa
2021-12-19  1:00 Dave Plonka

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