>Hi > >I am new to this list and would like to discuss an idea and ask several >questions.
Hi Alex. I am retired, and haven't worked with mainframes for a long time. However I own several 3174s and 3270 compatible terminals (If any in Europe has a spare IBM 3270 it would be nice to have a copy) I know others have replied so please excuse ant duplications... >* Did anybody ever attempt to 'talk' to 3270 terminals with something > different than an IBM mainframe? > >This might sound like a strange idea, though I find it intriguing to be >able to display content on such a terminal and be able to receive >keyboard input from it. > >I guess the most straight-forward way to attempt something like that is >to use a 3270 terminal attached to a 3174 or similar and try to talk to >that instead of the terminal itself. I wouldn't know how to interface >with the terminal directly over the coax. Well some one has attempted that and details of their work can be found here:- https://github.com/lowobservable/oec >* What's the best available documentation regarding 3174 models and > their features? > Well I guess "3174 Introduction (GA27-3850-06)" is a good place to start. There is a copy of the -00 version in PDF on bitsavers, but as far as I know the latest version, so the -06 is only available in Bookmanager format from the IBM Publications Center and it a lot of info missing from the -00 version https://www-05.ibm.com/e-business/linkweb/publications/servlet/pbi.wss just search for "3174". . You will need the IBM Softcopy Reader to read them https://www.ibm.com/support/pages/ibm-softcopy-reader >I poked around on ibm.com and google but wasn't able to find much. It >seems like there were several different physical-layer north-bound >interfaces for 3174. Bus&Tag, Token Ring, Ethernet, RS232 (if I am not >mistaken, for dial-up connections), maybe others? There is also X.21 as a serial interface >Bus&Tag doesn't seem to be a good candidate, it's difficult to interface >with as far as I understand. >Ethernet is way more common these days than Token Ring, though TR NICs >are easy to procure second hand and protocol support under Linux (the OS >I am most savvy with) is in place. >RS232 is easy to interface with also, though then again, I am not sure >if that interface really exists. Older CISCO routers are a good way to get many of the older protocols listed here to a modern system So I have a CISCO router with Token Ring and Ethernet so a Token Ring 3174 can connect to my Ethernet LAN They are also available with Ethernet Interfaces and so can encapsulate SNA or BiSync into IP There is an IBM Red Book on using the 3174 in TCPIP netwowrks on BitSavers. http://www.bitsavers.org/pdf/ibm/3174/GG24-4172-0_Using_3174_in_TCP_IP_Networks_Jun94.pdf > >* Did the LAN interfaces (Ethernet, TR) talk SNA on layers 2 and 3 or > was there by any chance something going on with TCP/IP? I doubt it > though. Normally to an IBM host you talks SNA. Later releases of the software will also go out on standard Telnet for Unix/ASCII hosts or TN3270 for IBM hosts. So with my 3174 with Ethernet interface I can connect to both the 4361 at LCM+L and the DECUS VAX eisner.decus.org. >Talking SNA with custom software doesn't seem to be a low-hanging fruit. >From where I stand right now I cannot say how straight-forward the >network traffic between the mainframe and a 3174 is, how difficult it >would be to emulate that protocol with custom software over several >layers. It has been done, well using IBM software. So connecting a 3174 to a CISCO then feeding that to a modified Hercules running MVS 3.8J. >* Is anybody on the list here able to provide protocol traces from the > link between mainframe and 3174 over any interface? pcap format is > preferred, though anything would be valuable. I don't think any one has needed to dig that deep. Its all well documented. The 3270 datastream manual is rather over comprehensive but its what goes across the session. Its also important to remember what goes between the terminal and the 3174 is very different to what the 3174 send to the host. This is one reason Mainframes were much more scalable than other architectures. The 3174 (and 3274 before) takes most of the work of talking to terminals away from the host. >I would appreciate any thoughts regarding this topic, especially to the >questions marked with asterisks. >Also, if anything is known regarding a similar thing with 5250 instead >of 3170 terminals, that would be interesting as well. I know very little about 5250 > >-Alex Dave ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
