I don't know if I would go so far as to say hardly relevant. The Unix stream model is quite close to Tops-20's. For TCP, there is a certain amount of shared conceptual ancestry. Both Tops-20 and Unix have the idea of attempting to divorce the program from the data it is reading, which allows you to pick different devices with relative ease at the user level (think pipes)
BSD broke this paradigm with sockets because now you can't pipe
into them. Plan 9 doesn't do that. Tops-20 broke this in exactly
the same way except that they're called JCN's, but you have an
entirely separate set of JSYi to talk to the network. This is
what I mean by a shared conceptual framework as I believe these
were two of the early TCP implementations.
Tops-20 dropped the JCN stuff to switch back to a JFN interface,
which makes programming this a lot simpler. MRC and the rest of
the ARPA community made a pretty big stick about doing it "the
right way"
When you are trying to figure out the way something works, it is very useful to see how different operating systems are implementing the protocol. For Tops-20 FTP, I had source for Tops-20, ITS and BSD FTP and that helped me understand a conceptual and then fix a problem with passive mode (which the Tops-20 FTP client had not implemented).
It is a very sad fact that the number of operating systems in active use has vastly decreased because there are less cross fertilization opportunities. And if you want to bullet proof your code, have it run on different OS's...
I really grind my teeth when I see some You-Boob'ers talk about
different OS's when they're just really different versions of
Windows. Same API, different glitz. Big deal.
On 11/26/22 11:49 AM, Johnny Billquist wrote:
The Unix stream mode sockets over DECnet was an interesting detail. I think I might have seen them mentioned before (maybe by John Forecast then too?), but since noone else would understand them, it's hardly relevant for TOPS-20. But it's cool to hear about, and I think it would obviously not be hard to add such a layer in between, to get this kind of semantics, if one wanted to.