IBM 3174 C 6.4 Microcode Disks?

Grant Taylor cctalk at
Sat Feb 16 20:36:11 CST 2019

On 2/14/19 10:03 PM, Kevin Monceaux via cctalk wrote:
> I also acquired an RS/6000 7012-340,  its 7208 8mm tape drive, and a 
> couple of 9121 voice servers.  It used to run DirectTalk/6000.

I'm running into collisions with IBM 9121 and mainframe components. 
Even that is vague.  I'm not having nearly the luck I usually do looking 
up IBM four digit model numbers.

> I might have the terminology wrong.  I not very familiar with the token 
> ring side of things.  By the time I got into mainframe operations about 
> twenty years ago we only had a few token ring devices left.  The RS/6000 
> mentioned above was only connected to the token ring side of our network. 
> It connected to the 3174 via token ring to screen scrape emulated 3270 
> sessions.  Before the RS/6000 was shut down, I was able to telnet to it 
> from my PC, which was on the Ethernet side of the network.

So you had IP connectivity from Ethernet to Token Ring.  That's trivial 
to do.  The Cisco 2513 would be a very good candidate router to do that.

Many things can /route/ between Ethernet and Token Ring.  There are only 
a few things (that I'm aware of) that can /bridge/ between Ethernet and 
Token Ring.  Even then, the union of the type of traffic that works on 
both Ethernet and Token Ring is considerably smaller than either side.

TCP/IP inside of 802.2 SNAP frames will work.  But exceptionally little 
on the Ethernet side can, much less does, uses that for TCP/IP.  It's 
possible, but not likely.

I think it's far more likely that the 2513 was routing.  It may have 
also been doing some sort of NAT / port forwarding (which is largely 
modifying the packet before it's routed).

> The router in is the Cisco 2500 series, perhaps a 2513.  I found this 
> photo on the net, which looks like the router in question, if I remember 
> correctly:

Yep.  That's a quintessential Ethernet & Token Ring router.

> As for using telnet on the 3174, I'm going by what I've seen posted on 
> Hercules mailing lists about how others have connected real terminals 
> to the Hercules mainframe emulator.  A few pictures of such terminals 
> connected to Hercules can be found at:

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 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 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".

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 

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.

Grant. . . .
unix || die

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