Re: PDP-11/70 Boards

[Noel Chiappa via cctalk]

> From: Guy Sotomayor

> I don't unfortunately have any light masks

Dave Bridgham and I were manoeuvreing to be able to produce clones of the one
you loaned me (he has access to a computer-controlled milling machine at his
maker-space or whatever the name is for them now, and we bought a good-sized
sheet of the required plastic to be able to crank them out) when I came down
with COVID early in the pendemic, and in the aftermath (I came down with
long-haul post-COVID Chronic Fatigue Syndrome) itgot put on hold. The loaner,
and a micrometer to measure it, are still siting on the table in my family
room, next to my desktop.

If anybody needs some, I can probably try finishing the drawing, and get it
to Dave, so we can resume that project.


Noel

Re: PDP-11/70 Boards

[Noel Chiappa via cctalk]

> From the blog of someone who got a KB11-A working

It's Fritz Mueller's blog; at about the top of this page:

  https://fritzm.github.io/category/pdp-116.html

he's just turned the machine on for the first time, and you can
follow as he chases, finds and fixes CPU problems. The KB11-C/D
of the -11/70 is _very_ similar to the KB11-A he was dealing with
(they are _basically_ the same CPU, with a cache, and other stuff
added on the other side from the CPU, on the KB11-C/D), so there
are probably some good lessons to be learned.


> dunno if Guy Steele

Ooops; sorry, Guy - the brain is starting to drop bits.


> if the particular machine the system is being built for has an FP11).
> Perhaps the later BSD versions look for the FP11 on startup, and adjust
> their behaviour appropriately, but I'm not familiar with them.

The way user code deals with the existence/non-existence of the FP11 is
pretty simple.

In C (other languages probably do something similar, but I only know about
C),one gives the '-f' flag to 'cc', and when 'cc' invokes the linker, on
machines which don't have floating point support, it uses fcrt0:

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s4/fcrt0.s

as the machine language startup (the thing that calls main()) instead of
crt0. The difference is that fcrt0 sets the UNIX 'illegal instruction'
signal, in that process, to go to a handler which emulates the FP11
instructions.

In V6, as distributed, the binary of all applications which use floating
point are linked this way, so they will all run OK 'as is' on a machine with
no floating point (including those which don't suppport any kind of FP11,
such as the -11/40). When run on a machine with an FP11, there are no illegal
instruction traps, and that emulator code is just never used.

I'm not sure what the deal with BSD is, for machines without an FP11; fcrt0.s
is still included in BSD2.9, so maybe it's still using this approach. I have
this vague recollection that at some point, floating point instruction
emulation was added to the kernel, removing all the signal overhead, but that
might be a bogus recollection.

Noel

Re: PDP-11/70 Boards

[Scott LaBombard via cctalk]

   On Tuesday, November 30, 2021, 04:24:37 PM EST, Jay Jaeger via cctalk 
 wrote:  > 
>
>Did you use that directly with ExpressPCB and order from ExpressPCB or 
>did you convert to more standard gerbers?

I have a gerber archive for the km11x.pcb file. If anyone can host it where it 
might be more broadly accessible, I'd be happy to send it along to them.


Scott
  

Re: PDP-11/70 Boards

[Todd Goodman via cctalk]

On 11/30/2021 4:42 PM, Fritz Mueller via cctalk wrote:

I built mine from a layout on Tom Uban’s site: 
http://www.ubanproductions.com/museum.html
Did you use that directly with ExpressPCB and order from ExpressPCB or did you 
convert to more standard gerbers?

I just went with ExpressPCB for minimal hassle, but you could probably get it 
cheaper from other board houses these days.  For my KB11-A + FP11-B, which run 
asynchronously, it was handy to build up two of these.  Also useful for the 
RK11-C.

   —FritzM.


I have Joerg Hoppe's KM11 bare boards available.

He also has gerbers available at 
http://retrocmp.com/tools/dec-km11-maintenance-panel


Todd

RE: Looking for someone in London (UK) to read 2 9 track tapes

[Joshua Rice via cctalk]

The Centre for Computing History in Cambridge might be able to help too.

-- Original Message --
From: "Dave Wade G4UGM via cctalk" 
To: "'Chuck Guzis'" ; "'General Discussion: On-Topic 
and Off-Topic Posts'" 

Sent: Wednesday, 1 Dec, 2021 At 09:42
Subject: RE: Looking for someone in London (UK) to read 2 9 track tapes
Chuck,
I think TNMOC can read these tapes.
https://www.tnmoc.org/ 

Dave
-Original Message-
From: cctalk  On Behalf Of Chuck Guzis 
via

cctalk
Sent: 30 November 2021 23:57
To: CCtalk 
Subject: Looking for someone in London (UK) to read 2 9 track tapes
Hey list,
I received a note today from a fellow in London who has 2 9-track tapes 
that

he'd like read.  Brands are CDC and BASF, so media shedding should
not be a problem.   Dates are '92 and '93, so likely 1600 or 6259.  The
tape seal on one (the other has no seal) is IBM-style, which may be the
system that produced the tapes.
Any takers?  Let me know if so, I'll put you in contact and you can take 
things

from there.
All the best,
--Chuck

RE: Looking for someone in London (UK) to read 2 9 track tapes

[Dave Wade G4UGM via cctalk]

Chuck,
I think TNMOC can read these tapes.

https://www.tnmoc.org/


Dave

> -Original Message-
> From: cctalk  On Behalf Of Chuck Guzis via
> cctalk
> Sent: 30 November 2021 23:57
> To: CCtalk 
> Subject: Looking for someone in London (UK) to read 2 9 track tapes
> 
> Hey list,
> 
> I received a note today from a fellow in London who has 2 9-track tapes that
> he'd like read.  Brands are CDC and BASF, so media shedding should
> not be a problem.   Dates are '92 and '93, so likely 1600 or 6259.  The
> tape seal on one (the other has no seal) is IBM-style, which may be the
> system that produced the tapes.
> 
> Any takers?  Let me know if so, I'll put you in contact and you can take 
> things
> from there.
> 
> All the best,
> 
> --Chuck
>