[TUHS] PDP 11/23 running UNIX version 6 at VCF Midwest!

[Noel Chiappa]

    > 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