[Simh] DECnet for TOPS-10

Sat Apr 13 20:18:33 EDT 2013

> Did I remember wrong in that I thought I had seen something from MRC 
> in the past where he said he had managed to get phase IV for TOPS-20 
> running on a KS? 
MRC may well have reconstructed a V5 monitor for the KS from the 
sources, but that's not DEC product.  And unless he did a lot of work, 
it would have been an interesting toy, but not product quality.

Support for TOPS-20 on the KS ended with V4.1 (Phase III).  The most 
pervasive changes in Phase-IV were a consequence of supporting broadcast 
media.  DECnet Phase IV was initially developed on a KS with a 3-Com 
ethernet card, as the DEUNA took too many slots, and the KLNIA wasn't 
ready.  (The DECnet, LAT and SCA modules were ported to TOPS-10; some of 
the TOPS-10 changes went back into the DECnet group's sources.)  As the 
DECnet code grew, more modules were moved into extended sections, 
including the SCA (CI) and cluster drivers.  It was barely possible to 
boot V5 on the KS if you cut back on a lot of configuration parameters, 
but DEC never shipped it because there wasn't enough exec address space 
left over (or resources) for a reasonably configured/responsive system.  
It was held together to support DECnet development for quite a while, 
but over time the dependencies on extended addressing grew.  Once the 
KLNIA was stable, the DECnet group abandoned the KS, as did the monitor 
group.

TOPS-20 development decided to stabilize the KS at 4.1 rather than 
invest in making 5.0 production quality on the KS.  Since support was in 
another group, they didn't bear the costs.  A few people in the support 
group had 5.1 running on the KS as a support tool (didn't want to get 
rid of their KS system, as it was a lot cheaper in floor space, power, 
and maintenance than buying/running another KL.)  But that was 
scaled-down & not product quality. I don't recall them succeeding (or 
even putting much effort) at later versions of TOPS-20.  The leftover 
tracks in the sources would probably be the basis of MRC's work.

I made a different call for TOPS-10.  I updated the KS microcode to 
support the version of KL paging that TOPS-10 used (but still a single 
section), and made Phase IV work.  JMF & I then came up with the 
slight-of-hand to create an alternate address space for DECnet, allowing 
TOPS-10 to also support a reasonable number of users.  Presented with a 
fait-accompli, product management saw the benefits and allowed us to 
ship it.  Happy customers.  And we only had to support one version of 
the monitor through end-of-life of the 36-bit product line.
>> TOPS-20 can participate in a modern network. 
> More or less. There are some restrictions. 
Yes, but in this context, they're not significant.  TOPS-20 Phase-III 
will talk to a Phase IV system.  Routing is different; the Phase-III 
node doesn't know about areas, and (obviously) anything new in Phase-IV 
doesn't magically appear in the Phase III implementation.  But Phase-III 
routers and end nodes can happily co-exist with Phase-IV on serial 
links.  NCP works.  And PMR can be used to allow the Phase III nodes to 
communicate across areas.

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

On 13-Apr-13 19:05, Johnny Billquist wrote:
> On 2013-04-14 00:39, Timothe Litt wrote:
>>> That sounds like we can get DECnet on TOPS-20 on SIMH, if so that
>>> would be
>>> really great!
>> Yes.
>>> Which phase(s) does TOPS-20 DECnet support on the KS?
>> Phase III.  Because it was so large, Phase IV used extended sections
>> (addressing), which the KS doesn't support.  I used slight-of-hand to
>> make Phase IV fit into TOPS-10 on the KS10.
>
> Did I remember wrong in that I thought I had seen something from MRC 
> in the past where he said he had managed to get phase IV for TOPS-20 
> running on a KS?
>
>> But Phase III will connect to a Phase IV node, so TOPS-20 can
>> participate in a modern network.
>
> More or less. There are some restrictions.
>
>     Johnny
>
>>> Adding DMR support was on my list, but I haven't done it yet. I'll see
>>> if I
>>> can get the KMC/DUP code in and then do DMR, but it may be a while
>>> before I
>>> get time.
>> That would be super.  It looked like your code has some hooks for DMR,
>> but is incomplete.  Given that you don't actually do DDCMP, the
>> differences should be small.
>>
>> -- 
>> This communication may not represent my employer's views,
>> if any, on the matters discussed.
>>
>> On 13-Apr-13 18:25, Rob Jarratt wrote:
>>>
>>>> -----Original Message-----
>>>> From: Timothe Litt [mailto:litt at ieee.org]
>>>> Sent: 13 April 2013 22:40
>>>> To: r.jarratt at computer.org
>>>> Cc: Rob Jarratt; 'Johnny Eriksson'; simh at trailing-edge.com
>>>> Subject: Re: [Simh] DECnet for TOPS-10
>>>>
>>>> On 13-Apr-13 17:00, Rob Jarratt wrote:
>>>>> I wrote support for the KMC/DUP combo a long time ago, for simh v2.9.
>>>>>
>>>>> Works just fine, both for ANF and DECnet.  Sources are (still) at
>>>>> ftp://ftp.stacken.kth.se/pub/pdp10/v29upd if anyone is interested.
>>>>>
>>>>> I do not have any system up at the moment, due to a combination of HW
>>>>> problems and lack of time.
>>>>>
>>>>> --Johnny
>>>>>
>>>> If KDP (KMC/DUP) still works, it should be integrated into the PDP10
>>>> simulator.  TOPS-10 (ANF-10 and DECnet) supports the device, and 
>>>> TOPS-20
>>>> (DECnet) supports it.  Both on the KS10.
>>>
>>> That sounds like we can get DECnet on TOPS-20 on SIMH, if so that
>>> would be
>>> really great!
>>>
>>>
>>>>> It went into the PDP10 emulation for a while but was later
>>>>> removed when we were informed that it would have represented an
>>>> impossible
>>>>> configuration as the DMC11 would have been in the PDP11 front end.
>>>> Whoever provided that information was correct for the DMC, but not for
>>>> the DMR.
>>>>
>>>> For the KL, yes, the DECnet serial line adapters were in the PDP11 
>>>> front
>>>> end.  Ethernet was on an internal channel.
>>>>
>>>> If the DMC can be configured as a DMR, it should go into the PDP10
>>>> simulator.
>>>
>>>
>>> Adding DMR support was on my list, but I haven't done it yet. I'll see
>>> if I
>>> can get the KMC/DUP code in and then do DMR, but it may be a while
>>> before I
>>> get time.
>>>
>>>
>>>
>>>
>>> As I said, I wrote a KS10 (Unibus) driver for the DMR on
>>>> TOPS10, which is in the distributed OS sources.  The DMC is useless on
>>>> the KS10.  As I noted, the DMR uses fixed addresses in TOPS-10, not 
>>>> the
>>>> usual Unibus floating addresses.
>>>>
>>>> Either device would allow TOPS-10 networking to work under simh. 
>>>> TOPS-10
>>>> can be configured for either or both devices.  TOPS-10 DECnet will 
>>>> work
>>>> as either a Phase III or Phase IV end-node on the KS10.  (I did the
>>>> Phase IV implementation for the KS.)
>>>
>>> Which phase(s) does TOPS-20 DECnet support on the KS?
>>>
>>>
>>>> I was a developer for TOPS-10, and supported TOPS-20 (among other
>>>> things), so this is authoritative.
>>>>
>>>> This communication may not represent my employer's views,
>>>> if any, on the matters discussed.
>>>>
>>
>>
>>
>>
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>> http://mailman.trailing-edge.com/mailman/listinfo/simh
>>
>
>

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