RE: Re: Where do I start?

> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of Gerhard Postpischil
> Sent: 28 May 2010 04:55
> To: [email protected]
> Subject: Re: [turnkey-mvs] Re: Where do I start?
> 
> 
> On 5/27/2010 9:33 PM, Ron Hudson wrote:
> > hmm let me ask that more directly- When I am tabbing between fields 
> > and editing the information there, Is Hercules operating or is the 
> > 3270 emulation I am using providing that?
> 
> That's your emulator at work. Hercules doesn't know what you did 
> until you hit an attention key.
> 
> > I ask since the 3270 emulator connectes to Hercules via a telnet 
> > session (on a strange port)...

It's a "strange port" because only one program can listen on one port/ip
address pair at any time. So if the system on which Hercules is running
already has something listening on the normal TELNET port, Hercules can't
use it. On most Windows systems its OK to set the port number to the normal
one for Telnet (23 I think). 


> 
> To be pedantic, it's unlike to be telnet (line mode), but rather 
> tn3270 or tn3270e
> 
> > If I had a real 3270 and a real controller could I hook it to 
> > hercules?
> 

I would say only by cheating ;-) . You can't hook the controller up to
Hercules, but some 3270's can act as a TN3270 client, and so can connect to
Hercules. However Hercules won't "know" it's a "real" 3270 on the end of the
line, and it will look to the OS like a local channel attached (see below)
3270. 

Originally 3270 controllers could be physically connected to a mainframe in
number of ways. There were "local channel attached" which connected directly
to the channel system via "Bus and Tag" cables. These are what Hercules
emulates. To connect one of these to a PC would require a S/370 channel card
in the PC and as Hercules has no drivers you can't connect a 3270 to Herc in
this manner. 

As the name implies "Local" controllers must be close to the mainframe (not
sure what the max length of bus+tag probably 500ft or so), and (normally) a
3270 can't be more than about 1500yds (say a mile) from the controller you
needed an alternative connection method. So there are remote 3270's which
connect by Syncronous communications lines (SDLC or Bi-Sync). So whilst
syncronus comms cards are not unkown for the PC, again Hercules does not
understand them so you can't connect that way.

Lastly there are Token Ring or Ethernet attached controllers. Note that
these still don't (normally) use TCP/IP they use SNA protocols over the
network so they won't pass  through modern routers. 

These normally connect to the Mainframe via a "Front End Processor) say a
3745 or 3725. As these are computer systems in their own right you would
probably need an extra emulator for these, so again you can't connect to
Hercules in that way.
 
> If you have to ask, no <G>  Some IBM controllers (with a -R) 

You can also add a token ring card to many none "-R" controllers. These
could be used to get Token Ring access onto the mainframe without having a
3720, 3725 or 3745. When my workplace had a mainframe we had several
controllers like this to get traffic from IBM's "SNA server for Windows"
into VM and VSE. Both Microsoft and IBM produced SNA Server products that
could act as remote token ring attached 3270's. You could use a TN3270
client to connect to the SNA Server software. This then connected you to the
Mainframe as if you were on a real 3270 controller. I don't think the free
MVS has support for this type of 3174 so again not much use to many
Heruleans.

> suffix come with an ethernet or token-ring connection, and you 
> can get matching cards for your PC (ethernet controllers are 
> more desirable, hence more expensive). But you'll probably need 
> professional help to set everything up and generate the system 
> floppies.
> 
> Gerhard Postpischil
> Bradford, VT
> 
Dave
G4UGM