[Simh] [SimH] Networking support

Sat Mar 12 17:53:48 EST 2016

Well RFC 791 doesn't mention any "link control protocol". Maybe it never existed. Well modern man's highest acheivement launched in 1983 I see then. I just can't get over the way IP packets split, find the shortest routes and recombine at the destination :) amazing. PDPs are certainly mentioned in rfc 791 !

Bill

  ----- Original Message ----- 
  From: Michael Short 
  To: SIMH 
  Sent: Saturday, March 12, 2016 5:36 PM
  Subject: Re: [Simh] [SimH] Networking support

  On the history of networks, there was also a network called BITNET which was mainly used
  by educational institutions using mainframes. Started around 1981, it was originally based on 
  the bisync protocol and was a store-and-forward system. At it peak it had about 500 organizations 
  and about 3000 nodes. Toward the end, it morphed into BITNET II using TCP. 

  On Sat, Mar 12, 2016 at 3:31 PM, Clem Cole <clemc at ccc.com> wrote:

    Bill,

    You probably need to date things a little and get a some perspective of where a few of us are coming.   Just to set a few lines in the sand.  While 3Mb/s "xerox" ethernet has been around for about 5 years, the DEC/Intel/Xerox Ethernet 10Mb/s spec was published Sep 30, 1980.   Per RFC 801, Arpanet was not officially schedule to switch from the old NCP to IP until Jan 1, 1983 (although a number of folks like me had been working with what would become IP/TCP for 3-4 years before that).  But "networking" as we think of it today, had been around for over 10-15 years before that - i.e. long before the rise of the PC.

    Most large (mini/mainframe) manufacturer have their own networking.    Consider DEC's VMS, the original IP/TCP implementation was written by me and my co-workers at Tektronix at the time (1979-80).  DEC wants us to use DECnet.   We also have CDC, UNIX boxes and even a IBM mainframe.   We needed something that could span the OSses.  It was easier for us to write our own implementation because what we wanted was a network that spanned our companies use, not one manufacturer.

    Moreover "Metcalfe's Law" is also very important (the value of a network is proportional to the exponent of the number of the things connected to it).  So ... each manufacturer had their own scheme - both HW and SW.   The widest "general" system was the Arpanet "IMP" system that DoD paid to have interfaced to a number of different systems; although as has been discussed PDP-10's, 11s and eventually Vaxen were a large number of the systems on that network.  So in fact, that was the most valuable network because it had the most systems connected to it that had cool things that could used/shared.

    Actually, the largest reaching network at the time was the Unix UUCP network, which allowed email and file transfer (al biet a tad slowly). There were thousands of sites on it.  In fact the UUCP site "ccc" pre-dates ccc.com being registered to me because in those days people could not register a domain name.  But "usenet" could not do things like telnet and was a good bit less formal that the ARPAnet or the Internet.

    Roll forward and think of PC's.   Please remember with the PC's pre-ethernet  too were often "networked" most often with ARC-net HW (75 ohm coax - very cheap), running either Netware or LAN-Manager.   Like, DECNet and the systems from the mini's and mainframes, it allowed PC to send files around, share printers, send email etc.   But like all other proprietary systems, it was closed so it's not talk to your Vaxen or UNIX systems etc.  The size of these networks tended to be the size of your office during Word/Excel et al.   Which was fine for a lot of people... but....   it's a little like having a local walkie-talkie that is not connected to the larger network and you can talk to a few people.  When you finally realize you need to talk to someone outside your firm, you note how limited it it.

    So... between the US Gov paying for the SW to be written to support a # of OS's they cared about, the rise of UNIX, and MetCalfe's Law, IP became the protocol and ethernet became the HW that "stuck" - i.e. the rise of the Internet.

    Now consider that by the time the PC and BBS system that PC's used come on the scene you have a quite a different view.  Also, BBS's were really not a network in the same way the mini's and mainframes worked.  A person that knew a phone number and had an account to call a remote system.   But this is quite different from how the DECNet, SNA, Arpanet, etc (or for that matter UUCP) worked. 

    Back to your question...  if we want a simulation system to support networking in the way most of us think of it, we need two things.   First the HW needs to emulate some know HW that was developed and released by the manufacturer.  Second, you need the OS support for same.

    Frankly, it is probably not worth investing a lot of effort into writing the HW emulation unless we have the SW to drive it.   And frankly, you need to think how you will use it.  Modulo Johnny and the cool folks running HECnet (a large world wide network running DECnet over the Internet), you probably will want to have Internet functionality to be able to access the systems. 

    The good news is that a number of folks developed implementations for almost most of the major OS implementations and many of the manufacturers eventually picked them up (DEC would eventually take the Tek/CMU IP implementation in house). 

    The bad news is I fear except for a few cases where the manufacturer picked it up and made a product, some of those stacks (like the HP-1000 and HP-3000 stacks from BBN) have been lost.   If someone has those it would be cool, but I have not seen those bits since the early 1980s.

    Clem

    On Sat, Mar 12, 2016 at 2:36 PM, Bill Cunningham <billcun at suddenlink.net> wrote:

      What I meant was that I remember on early PCs using an rs232-c line for using the old BBSes and compuserve before it was an ISP. 10 cents a minute. I had several modems 300, 1200 and 2400 baud modems. 

          These even older machines may have had hookups within a company. Even one building connecting 5 or so machines. Serial would've worked fine. And was what was used. I was thinking with maybe 4-5 PDP8s a company would use some kind of networking. Perhaps not back then. I was only aware of pdp11 and vax being "network possible". I guess I was wrong.

      Bill

        ----- Original Message ----- 
        From: Clem Cole 
        To: Anders Magnusson 
        Cc: SIMH ; Bob Supnik 
        Sent: Saturday, March 12, 2016 2:24 PM
        Subject: Re: [Simh] [SimH] Networking support

        On Sat, Mar 12, 2016 at 12:25 PM, Anders Magnusson <ragge at ludd.ltu.se> wrote:

          DG-UX or MV/UX? 

        Which was the rewrite of System V ?? i.e. System V cmd system, but internally developed System V SMP kernel -- I want to say DG-UX maybe; but I'd been a long time and many beers ago - I've forgotten the name.   I remember it was a very clean UNIX implementation.   Nice locking structure, easy to debug, etc...

        Locus was working on different projects with Ultrix, Tru64, VMS, AIX, SunOS, Solaris, HP-UX, Apollo, DG's UX, some work for Pr1me, ISC's 386/ix, Intel's 386 port, SVR4 for the AT&T/UI guys, and Intel's Paragon at the same time.  At one point, I had the OS release schedules for HP, DEC and Sun all pasted on the wall behind my desk.  I used to say LCC got to see everyone's dirty laundry in those days.  As I said, I do remember the DG Unix re-implementation was very easy to work on (I will not say which one we cursed the most).

          The DG ethernet card has a 82586 on board. 
        As I said, many beers ago. I'm undoubtedly mixed up a couple of the systems, since we had so many we worked with in those days.  I remember the AMD chip was a lot easier to program than the Intel device. That said, I suspect that I have the docs on the Intel chips somewhere, but it sounds like others have the DG docs which are going to be better for simh purposes.

        Clem

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