Re: GDB front-end for SimH

[Paul Koning via cctalk]

> On Apr 24, 2018, at 8:14 PM, Maciej W. Rozycki  wrote:
> 
> On Tue, 24 Apr 2018, Paul Koning via cctalk wrote:
> 
>> One drawback is that there aren't all that many SIMH architectures that 
>> have GDB support.  VAX does, and Alpha; that's about it.  I don't know 
>> how hard it is to do a basic platform in GDB, probably not all that 
>> difficult.  At least for machines like PDP-11.  One's complement might 
>> be harder (PDP-1), never mind things like the IBM 1620...  :-)
> 
> You need target BFD and libopcodes support for a GDB port to be possible.  
> There is such support already present for PDP-11, so wiring in GDB parts 
> should be straightforward.  A remote protocol stub for SimH should also be 
> easy to write as you don't need all the fancy stuff and GDB will be happy 
> to work with just the `?', `G', `M', `c', `g', `m' request packets and the 
> `S' stop reply packet implemented.  The rest is optional.

True.  But if the SIMH code has breakpoint support, GDB can use that as a 
"hardware breakpoint".  Not all that interesting, perhaps, unless you're 
putting breakpoints in ROM.  More interesting is watchpoint support, which some 
SIMH targets have, and GDB supports.

I haven't tried to do a minimal BFD/opcodes implementation for a platform that 
doesn't yet have one.  PDP-10 perhaps (unless Lars did one years ago?).  One 
wonders if non-power-of-two wordlengths add complication, as they do in recent 
GCC.

I don't know if the SIMH execution and control frameworks make it convenient to 
hook up the GDB remote stub protocol. A stop to the SIMH console would want to 
be turned into a GDB remote interaction instead, and break signals from GDB 
would have to be recognized while SIMH is running the emulated machine.

paul

Re: GDB front-end for SimH

[Maciej W. Rozycki via cctalk]

On Tue, 24 Apr 2018, Paul Koning via cctalk wrote:

> One drawback is that there aren't all that many SIMH architectures that 
> have GDB support.  VAX does, and Alpha; that's about it.  I don't know 
> how hard it is to do a basic platform in GDB, probably not all that 
> difficult.  At least for machines like PDP-11.  One's complement might 
> be harder (PDP-1), never mind things like the IBM 1620...  :-)

 You need target BFD and libopcodes support for a GDB port to be possible.  
There is such support already present for PDP-11, so wiring in GDB parts 
should be straightforward.  A remote protocol stub for SimH should also be 
easy to write as you don't need all the fancy stuff and GDB will be happy 
to work with just the `?', `G', `M', `c', `g', `m' request packets and the 
`S' stop reply packet implemented.  The rest is optional.

 HTH,

  Maciej

Re: GDB front-end for SimH

[Paul Koning via cctalk]

On Apr 24, 2018, at 5:38 PM, Kyle Owen via cctalk  wrote:
> 
> Has anyone made a GDB front-end for SimH? Just curious. Seems like it could
> be an interesting way to tie an IDE to SimH, if one were inclined.
> 
> Thanks,
> 
> Kyle

I haven't seen one.  But it would certainly make sense to tie in a GDB remote 
protocol server, hooked to the breakpoint facility of the SIMH emulation for 
machines that have one.

One drawback is that there aren't all that many SIMH architectures that have 
GDB support.  VAX does, and Alpha; that's about it.  I don't know how hard it 
is to do a basic platform in GDB, probably not all that difficult.  At least 
for machines like PDP-11.  One's complement might be harder (PDP-1), never mind 
things like the IBM 1620...  :-)

paul

Picked up stuff from Pete's

[Alan Perry via cctalk]

For those follow the rescue of equipment from Pete Lancashire's place 
outside of Portland ...


I went out there last Friday. Pete was unavailable, so a friend of his 
let me and showed me where to avoid stepping.


The amount of stuff there was impressive/amazing/overwhelming. Aside 
from the test equipment and old telecom equipment that was pointed out 
when I was shown around, it was hard to focus on one thing because I 
would immediately see something else interesting that grabbed my attention.


I picked up seven Sun SPARC systems and three Compaq-branded Alpha systems.

The Alpha systems all went to a local (Seattle) person who is talking to 
Bill Gunshannon about possibly getting one out to him. One of the Alphas 
was a DS20 deskside and I never figured out what the other two were. 
They were narrower and longer than the DS20. There were also some loose 
72G Ultra3 SCSI HDDs.


The Suns were a SS1, SS2, two SS5s (one with a Netra top cover), two 
SS20s (one with its cover removed and MBus card and memory lying near 
it) and a SS1+ "prototype". I am keeping the SS1+ and a SS5. I have 
found a home for a couple more of them and will be looking for a home 
for the rest.


The SS20s are the most problematic. As you would expect from a system 
with its top cover missing, one of the SS20s does not display any 
diagnostic output or get to the OBP prompt after being powered on. The 
"good" one displays a "replace motherboard" message while going through 
its diagnostics.


Also, as you might expect, the one called a prototype was the most 
interesting to me. I am a long-time Sun employee and, while I wasn't 
around when the SS1+ was developed, I know people who were. It isn't 
like any prototype that they knew of. Still trying to figure out exactly 
what it is. The top cover is metal and slides over the chassis (not 
plastic and pivots into place like a SS1+. There are no external 
markings on it. It has a Sun SS1+ motherboard, Sun0424 HDDs, and uses 
SS1/SS1+/SS2 HDD carriers, but has a Sony (not Sun) labeled power supply.


As far as the 029 keypunch, it is still there. There was some confusion 
and the people who were supposed to come get it didn't. I have described 
to them where it is and how I would go about removing it.


alan

GDB front-end for SimH

[Kyle Owen via cctalk]

Has anyone made a GDB front-end for SimH? Just curious. Seems like it could
be an interesting way to tie an IDE to SimH, if one were inclined.

Thanks,

Kyle

MDL is running in ITS

[Lars Brinkhoff via cctalk]

Hello,

People have been earching for PDP-10 MDL for a long time.  Finally, we
found source code for TOPS-20 including slightly bit-rotted ITS support.
It has now been fixed and is up and running in ITS.  Twenex people are
welcome to give it a go too.  This is published with permission from
Chris Reeve and Tim Anderson:

http://github.com/PDP-10/muddle

Next is, of course, trying to run Zork.  How to do that is an entire
research project of its own.

Best regards,
Lars Brinkhoff