Networking in 1980s

Networking in 1980s: a Personal View

I first encountered the concept of computer networks during a summer job I had at Iskra Delta. Someone pulled me to his terminal and said “here, you must see this”, and showed me how you could copy files from one minicomputer to another. That was interesting, but I was even more impressed with the ability to log into another minicomputer, particularly going from a VAX/VMS to a PDP-11 (or vice versa).

PDP-11-70-DDS570.jpgPDP 11/70 (Source: Wikimedia Commons)

You might have guessed that I’ve seen DECnet Phase IV (or maybe Phase III). It never really took off on the PDP-11 minicomputers because the networking components took too much memory – these machines had up to 1 MB of RAM with most of them having 64K – 256K – but VAX/VMS was a totally different story, particularly a few years later when even the low-end models shipped with megabytes of memory.

273px-VAX-11-750.jpgVAX-11/750 (Source: Wikimedia Commons)

In those days a large group of enthusiasts build a country-wide DECnet network (SLOvenian Network – SLON – which happens to mean elephant in Slovenian) that had hundreds of nodes… all based on “let’s get together” mentality and people willing to buy a leased line to someone who had a spare RS-232 port. We exchanged emails, participated in discussion groups (I’m still looking for a discussion forum that would be as elegant as VAX/VMS Notes) and exchanged information way before we first heard about Internet (which happened in late 1980s).


SLON network in 1991, courtesy of Davor Šoštarič, author Matej Wedam
Most of the leased lines used asynchronous modems connected directly to terminal ports, resulting in link speeds between 9600 bps and 38.400 bps. While the baseband modems used in those days provided link speeds between 64 kbps and 1 Mbps, the synchronous ports were usually way too expensive to be used for what was effectively hobbyist networking.

Some of these installations eventually started using a technology faster than leased lines based on thick coaxial cable that had to be yellow – the first Ethernet. A few years later, thin coax Ethernet appeared, local area networking exploded… and eventually we discovered the weird thing called TCP/IP.

SLON continued to run till at least late 1990s (with some islands still running after 2010, see the comment from Aleš Časar), and the latest node name file (think /etc/hosts) has over 1500 lines – we got to a point where a single DECnet area became overcrowded, so large users, particularly those using DECnet on PCs, moved into their own DECnet areas.

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Comments from the blog post

Oleg Arkhangelsky on 28 July 2016:

VAX 20 years later... In Russian, but with many print-outs. http://www.phantom.sannata.ru/konkurs/2015/kt1508.shtml

Aleš Časar on 28 July 2016:

I really, really enjoyed reading this article! Thank you!

There is probably a mistake and you wanted to say that you heard about Internet in late 1980s instead of late 1990s. I have heard about Internet in 1990, started to use it in 1991 (in Germany, connecting there via X.25, writing DCL scripts which FTPed listed files, split them, uuencode them and sent them to me via email over X.400 and similar odd technologies) and been on native Internet in Slovenia in 1992.

AFAIK with the advent of the Internet in Slovenia majority of backbone SLON links were replaced with same links used for Internet and "VAX routers/gateways" replaced with dual stacked (IPv4 + DECnet) Cisco routers. Later, due to licence issues many native long distance DECnet links were reconfigured with a bunch of DECnet over IPv4 tunnels which continued to run at least until mid 2000s. I remember some routed (e.g. between many VLANs in a campus) islands of SLON operating at least until late 2000s and reduced to single VLAN at least in 2012.

Ivan Pepelnjak on 29 July 2016:

You're absolutely right - Internet started appearing for real around 1990. Fixed.

Donatas Abraitis on 29 July 2016:

Unfortunately my first touch with computer was when dial-up connections already existed, but I'm happy that I know even what it is. When I talk with my colleges about historical networking stuff, almost nobody remembers even ISDN or DSL..

Stephan Wasserroth on 1 August 2016:

Nice reading, refreshing old memories...

I am able to top this ;-)
One of the first data networks in Germany was the HMINET1 (developed by the informatic department of the "Hahn-Meitner-Institut" in Berlin). When I was working there as a student, the HMINET2 based on X.25 was put into operation. There was remote terminal access, file transfer, RPC-interface and even a network management interface.
For the history buffs: https://cds.cern.ch/record/862971/files/p201.pdf

And yes, the VAX 11/780 mentioned in the PDF had the serial number 6 (if I remember right) and was running initially VMS version 0.8... Later, when I was leading the Process Computer Group we joined HEPNET/SPAN, a worldwide DECNET-Phase IV network. No firewalls included ;-) Germany was late regarding IP-networks.