3270 controller simulation

[Dave Wade]

> -----Original Message-----
> From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of Grant Taylor via
> cctalk
> Sent: 18 November 2019 21:32
> To: cctalk at classiccmp.org
> Subject: Re: 3270 controller simulation
> 
> On 11/18/19 1:37 PM, Dave Wade via cctalk wrote:
> > One thing which complicates things is that we have (roughly) layered
> > protocols in place between the 3174 and the host.
> 
> Yep.
> 
> I'm trying to actually map them in my head.  I may have to transition to paper /
> white board.
> 
> > So at the physical level we have channel attached, SDLC, Token Ring
> > and bi-sync.
> 
> *nod*
> 
> I think there's Ethernet in there too.
> 

Yes that’s in there....


> > Above that we have the channel protocols, HDLC/SDLC and bi-sync polling.
> 
> ACK
> 
> IMHO both the physical (L1 in OSI terms) and protocol (L2) are decidedly locally
> significant and probably mostly agnostic to the higher layer network.
> 

BiSync polling gets in the way at the top....

> > Then we may have SNA (which encompasses many options) to transport the
> > data through the network.
> 
> I am guessing that SNA is mostly agnostic to the lower protocols and worries
> more about data movement across one or more lower layer network links.
> 

Sadly no. If we are talking VTAM rather than TCAM then the layers are somewhat ill defined. From

http://vm.marist.edu/~vmshare/browse.cgi?fn=HUMOR91&ft=MEMO&args=sna+joke#hit

April Foolishness
==============

We present here fanciful ideas and interpretations related
to VM, IBM, and computing in general.

o Networking breakthrough:  for those  days when your   cooperative applications won't,  IBM introduces APPS
  (Advanced Program-to-Program Squabbling). This brings the   confusion and disruption of incompatible computers and
  unspecified interfaces to the farthest reaches of an   enterprise's network.

Append on 03/30/88 at 17:40 by Jean Rall Grumman Data Systems 516-575-7140:

Thought I'd pass this on;

Conversation between a caller and John Akers:
CALLER:  Hello, John?
AKERS:   Yes?
CALLER:  John Akers?
AKERS:   Yes?
CALLER:  John F. Akers?
AKERS:   Yeah?
CALLER:  John F. Akers, CEO for IBM?
AKERS:   Yes, what is it?
CALLER:  John F. Akers, CEO for IBM in Armonk?
AKERS:   Yes, that's right, what do you want?
CALLER:  John F. Akers, CEO for IBM in Armonk, ...?
    (etc. for a few more exchanges)
AKERS:   All right, enough!  What is going on here?!
CALLER:  Oh, not much John.  Just thought you would like to know what it
         is like to talk over SNA.

*** APPENDED 03/30/88 17:40:44 BY GDS/JEAN ***

And from

http://vm.marist.edu/~vmshare/browse.cgi?fn=HUMOR88&ft=MEMO&args=sna+joke+connection#hit

Append on 03/30/88 at 17:40 by Jean Rall Grumman Data Systems 516-575-7140:

Thought I'd pass this on;

Conversation between a caller and John Akers:
CALLER:  Hello, John?
AKERS:   Yes?
CALLER:  John Akers?
AKERS:   Yes?
CALLER:  John F. Akers?
AKERS:   Yeah?
CALLER:  John F. Akers, CEO for IBM?
AKERS:   Yes, what is it?
CALLER:  John F. Akers, CEO for IBM in Armonk?
AKERS:   Yes, that's right, what do you want?
CALLER:  John F. Akers, CEO for IBM in Armonk, ...?
    (etc. for a few more exchanges)
AKERS:   All right, enough!  What is going on here?!
CALLER:  Oh, not much John.  Just thought you would like to know what it
         is like to talk over SNA.

*** APPENDED 03/30/88 17:40:44 BY GDS/JEAN ***

Seriously the SNA Bind is an animal to reckoned with.  I haven't included the SNA manuals, but if you are suffering from insomnia you may wish to browse...

http://bitsavers.org/pdf/ibm/sna/GC20-1869-2_SNA_Introduction_to_Sessions_Between_Logical_Units_Dec79.pdf

> > At the top the protocols and frame formats in the Data Streams manual
> > which are broadly the same but with tweaks for SNA, Local and Bi-Sync.
> 
> Is this where APPN / APPC and the likes come into play?  Actual application
> information riding on top of SNA?
> 

Well sort of. APPN/APPC is deeply integrated in SNA. See above... 

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

Dave