IBM 3174 C 6.4 Microcode Disks?

Dave Wade dave.g4ugm at
Sun Feb 17 03:23:30 CST 2019

> I should look for more details.  It sounds like some 3174's, with proper
> firmware, can actually function in both directions.
> Coax connected 3270 terminals using the 3174 as a gateway to connect to
> something across the network (Token Ring or maybe Ethernet) via telnet.
> I suspect this is what a number of Hercules systems are doing.

I would say the 3174 is acting more as a Terminal Server rather than a gateway. 
So 3270 CO-AX terminals which are directly attached to the 3174 can connect 
via TN3270 to another host. Often this is Hercules where Hercules provides a 
a TN3270 server which is presented to the host as a channel attached 3174... 

A 3174 can have either a Token Ring or Ethernet interface but not both.
(it can also have hdlc/sdlc/bi-sync and bus+tag) 

> I think it's also possible to have (Token Ring or Ethernet) network connected
> clients telnet to and use the 3174 as a gateway to connect to ESCON / Bus
> and Tag machines.

The 3174 never acts as a telnet server but.........

A channel attached 3174 can be used to pass TCPIP into the mainframe 
and there are products that run on the mainframe that act as Telnet/TN3270 servers.
So in effect it acts as a channel attached network interface for the mainframe.

Some 3174s have RS232 ports, so locally attached serial terminals can 
connect to the mainframe. This can be via Channels or via remote network
connectivity, SNA token ring, X.25, SNA over Ethernet. 

> > The posts I've seen say one either needs a router to act as a token
> > ring to Ethernet bridge, or a PC with both token ring and Ethernet
> > cards in it to act as a bridge.
> I tend to agree.  My only qualm / uncertanty is "bridge" vs "route".

It depends on what is at the other end. If you are going TCPIP/TN3270 then 
normally you use a router. However if you are going SNA over LAN into 
the mainframe, from what I remember SNA LAN protocols are non-soutable
so you need a bridge/gateway.

If you run Hercules on a PC with a Token Ring card then you don't need anything.

> But this is likely the pedantic part of me that knows enough details to think
> "Wait, tab A doesn't directly fit in slot B, what gives?" in this situation.
> If the 2513 you have is the one that was used for this, I'd love to see the
> config, if it's still on there.  That would very likely settle things for my
> curiosity.  But that's likely not going to happen.  1) The config should have
> been wiped before leaving a business, and 2) you shouldn't show it to a
> stranger even if #1 didn't happen.

Do a search on "CISCO SNA Token Ring Bridging". Lots of papers on there.
Last time I fired this lot up I used the CISCO as an IP router and then used NAT
In the CISCO hide the token ring from main network.  Now I have a 3174 with 
An Ethernet card and a P390 with a bigger selction of Oss I have lots of options...

... but I am currently distracted by a pile of VAXen 

> --
> Grant. . . .
> unix || die


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