Interconnecting classic computers

Tony Duell ard at
Wed May 7 16:00:30 CDT 2008

> > I believe Tony also has a NetCommander which would let him select which
> Actually I have 3 of them. One is the 16 port model (with 16 RS232 
> ports), the others are the fixed-configuration 6 RS232/4 Centronics models.
> But they do not solce the cabling problem. Nor do they have enough ports 
> for all my classics...
> -----------Reply:
> Well, that gives you 25 ports; how many more do ya need? At one point we

Well, only given that I only need one connection at a time. If, as I 
suspect, you're suggesting using a pair of ports to link a pair of 
NetCommanders (1 port on each), you then can't have multiple connections 
between machines on the 2 NCs. 

I also have a JNT PAD (!). And although this was normally used as a 
packet assembler/disassembler to link terminals (and machines) to an X25 
network, I believe it can be configured to act as a smart switch. 16 

As regards haow many ports I _need_, I suspect i've got a total of around 
10 times that number (250-ish) RS232 ports on all my machines. And 
probably over 100 machines with one or more RS232 ports that I might want 
to interconnect. Of course I can't possibly have them all set up at the 
same time,

> had 4 computer ports feeding more than 200 terminals over a single connection.
> Alternately, it would be trivial to build a remotely controlled one-to-many port

One-to-many is easy, many-to-many is slightly harder, and the latter is 
what I would need. I am not looking to interconenct one of my classics to 
this PC, I am looking to interconnect any pair of my classics

> selector out of relays or solid state parts, and you could use the NetCommander
> just for the units that need baud rate conversion.
> Of course the NCs don't solve the cabling problem, that's why I mentioned the

And cabling is what I am primarily interested in.

> cordless phone. But unless you want to manually plug the desired system in
> every time or buy/make separate connecting links for every system, you'd

Given that I can't have lal the machines et up at the same time, there 
has to be some plugging/unplugging going on. Doing that is not a problem 
(nor do I object ot wiring up adapters for each of my machines to get the 
RxD and TxD on a consistent pair of pins in all cases, to loop back 
handshakes, and so on). 

> need some way of concentrating the systems into one connecting link.

Ture enough. 

> Obviously not a solution you'd approve of, but two old laptops with RS-232

Round here 'old laptops' are things like Epson HX20s, PX4s, PX8s, Tandy 
Model 100s, Olivetti M10s, HP110s, HP110+s and so on. Rahter _too_ old 
for this :-)

> and wireless cards would easily solve the connection problem. Of course
> we usually prefer lengthy discussions here instead of simple solutions...

But is it a simple solution?  I suspect I would find it quicker and 
easier to make a PSU and RS232 buffers for an Xbee module (and hope I can 
either ignore hardware handshaking or use it with machines that support 
it [1]) than to figure out how to configure the software on oen of said 

[1] Which, alas, excludes my DEC PDP8 and PDP11 machines :-(


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