14 Jul
2019
14 Jul
'19
9:16 p.m.
On Jul 14, 2019, at 1:48 PM, Thomas DeBellis
<tommytimesharing at gmail.com> wrote:
I had been wondering about the RSX DECnet packaging.
Pre-CI DECSYSTEM-20's may be modeled according to a loosely coupled multi-processor
paradigm, with the main KL being communicated with DTE20's, the master one having
additional rights. These were connected to either a front end communications processor
(which handled the communications, unit record equipment and I believe the ANF10) and
other networking. These were packaged in separate cabinets as DN20's.
The DN20 subsystems were 11/34 - 11/40 class machines, which might now be better thought
of as ancillary processors or even embedded systems, but sometimes were running cut down
versions of full blown operating systems. The front end ran a version of RSX called
RSX20F and was somewhat stripped down, not having a login.
A DN20 was termed a DN20 if it ran the 2780/3780/HASP communications code that IBMSPL
talked to. Since I was Columbia Galaxy nerd and knew PDP-11 assember, I also maintained
that code (and worked with our VM/MVS folks to fix a pesky bug in the multi-leaving
implementation). As I recall, this was embedded code and precisely RSX based (but
it's been at least 35 years since I assembled any of that). I think I used a 20 based
cross assembler to do it.
We did have an RSX20F pack, but I don't recall as I ever looked at source on that.
Or maybe it was on microfiche.
Do you know how DECnet would have been packaged for the DN20 and DN200 (the DECnet based
RJE station)? One assumes it would have been built off of RSX.
If the DN20 used DTE20?s to communicate with the KL, I would expect the code would
have been developed out of Marlboro. We (as in RSX DECnet development) had no PDP-10
hardware in our labs and would have found it difficult to code and test such software. The
only IBM communication product that I remember is RSX-2780 which ran on both 11M and 11D
as standalone applications - I believe there was some attempt to integrate it with CEX but
I don?t know if that succeeded.
The prevailing wisdom is that RSX20F is based on RSX-11D.
Around the end of Phase II development (late ?79, early ?80) we provided a snapshot of our
current development tree to Marlboro which was used to develop the MCB front end. Looking
at the code on Tim Shoppa?s site it looks like this is based on RSX-11S.
I can't remember whether the DN20 would do
anything past Phase III.
I was never involved in the IBM communications side so, unfortunately, I can?t
help there.
John.
> On 7/5/2019 7:57 PM, John Forecast wrote:
> What you see in CEXBF.MAC is all there ever was for CEX. When I joined the
development team in Jan ?77, an implementation of Phase II NSP was running standalone
under a ?Communications Executive?. The decision was made to ?port? this ?Communications
Executive? into each of the RSX-11 Decnet implementation (11M/11S/11D and IAS) and they
would all use this NSP implementation. As a side benefit we would get all the device
drivers that had been implemented as well.
>
> [...] that would be too expensive if every packet had to flow through NETACP. When a
packet is queued to a process (asynchronous rather than direct call) it is queued to the
NS: fork block. When NS: driver runs as a result it peeks at the request and may queue it
to NETACP or process it immediately.