[Simh] EXT :Re: PDP-10 simulation: DEUNA support help needed

[Hittner, David T (IS)]

As the original writer of the SIMH DEUNA device, I concur with Tim. If there had been a TOPS 10/20 DEUNA driver, I would have tried to test it during the SIMH DEUNA device development, but Tim, Zane Healy, Fred van Kempen, and others indicated that a production DEUNA driver did not exist, only a few partially-tested hacks. :-(
I do agree that 10/20 networking would be a desirable goal.

If you're trying to get DECNET running between a TOPS 10/20 implementation and some other DECNET-capable system, you have two choices:

 1) You can add a DEUNA driver to the TOPS OS to use the existing capability of the SIMH DEUNA Ethernet device
  Pros: Could support protocols other than DECNET (IP, LAT, etc.), better performance, more 'standard' implementation
  Cons: driver may not be easy portable to other 10/20 OS's, simultaneous driver/device debugging, custom driver must be added to each 10/20 OS install

or

 2) You could modify an existing SIMH device of one of the DECNET-supported point-to-point network device interfaces already supported  by TOPS to 'fake' the point-to point link over Ethernet by wrapping the data in an Ethernet packet and filtering the Ethernet traffic down so that it looks like a point-to-point link. Theoretically, no OS debugging would be required, but in practice SIMH device debugging tends to require walking the OS code to see the simulated device interactions. You might need to add some data buffering in the SIMH device so that the TOPS OS doesn't lose data due to service timing loops - Ethernet can be wicked fast compared to the speed of the old timing loops.
  Pros: no changes required to existing 10/20 OS drivers for DECNET III/IV, single device to debug
  Cons: possible timing loop data loss issues, more complex SIMH device behavior, not easily expanded for non-DECNET network protocols

If you're interested in pursuing the latter, remember to debug the Ethernet connections on a hard wire; wireless Ethernet has many implementation subtleties that make it difficult for non-IP protocols like DECNET. I might even be able to provide some midnight project help with either of these, although like Tim, I can't promise how much time might be available.

Dave

-----Original Message-----
From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Timothe Litt
Sent: Sunday, April 26, 2015 6:32 AM
To: simh at trailing-edge.com
Subject: EXT :Re: [Simh] PDP-10 simulation: DEUNA support help needed

Although I started to write a TOPS-10 DEUNA driver as a midnight project, I never finished it.  So far as I know no one else did, although the configuration support did find its way into the monitor. 
Sadly, there were (and are) only so many midnights, but the supply of projects is infinite.

DECnet-10 supports ethernet on the KL, but the code for broadcast devices (ethernet) is not conditionally assembled.  So in theory, it should be possible to write a (or complete my) driver.  That's on my list of projects - unfortunately, quite far down the list.  It would be very nice to have.  Note also that there is code to support ANF-10 over ethernet; that also needs to be hooked in.  Besides the driver proper, there are also tables that should be setup for NML.  The KDP/DMR didn't
- but they have out-of-band monitoring and are much simpler to debug.

SimH provides the hardware, but obviously that has never been tested. 
As it works on the PDP-11/VAX, I don't expect issues on the -10.  You should be able to set an address via SimH - for the real hardware, I picked something convenient (but I don't remember what it is).  The -10 doesn't autoconfigure its Unibus (although SimH has code to do so); all addresses are fixed.  You'd  put the address assignment (on UBA3) in pdp10_defs.h & see that it finds its way to the DIB - see auto_tab in pdp10_ksio.c.  Or just use set address.

The bottom line is that any support that you see in the monitor is illusory; either you wait for real support to find its way up to the top of my (or someone else's) project list, or take it on yourself :-)

Sorry.

P.S. Before someone asks:  TOPS-20 never had DEUNA support, and I never started that project.  Early DECnet Phase IV development was on TOPS-20.  It did use a 3COM ethernet board on the KS (this before DEUNA was available & long before the KLNIA).  That driver was discarded before the first TOPS-20 release of Phase IV, as the -20 group decided not to support the KS.  There was never a -20 DEUNA driver.

This communication may not represent my employer's views, if any, on the matters discussed. 

On 26-Apr-15 03:31, Cory Smelosky wrote:
> Hello,
>
> I'm (attempting) to get DEUNA support operating in the KS10 simulation 
> (likely incorrectly).
>
> I'm running in to some TOPS-10 issues assembling a monitor...does 
> anyone have a pre-genned TOPS-10 disk set up for DECnet on a KS10 with 
> ethernet I can use to test...if I even get that far?
>
> Current status:
> * Shows up in SHOW DEV
> * Has a vector
> * Links correctly
> * Can be enabled and attach to a host device
>
> ...and that's about all I have managed. Doesn't have an actual UNIBUS 
> address which is a LITTLE BIT OF AN ISSUE.
>