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From: WGLP09@SLACVM.SLAC.STANFORD.EDU
Newsgroups: comp.sys.amiga.datacomm
Subject: Re: IBM 327x emulation
Message-ID: <91112.174914WGLP09@SLACVM.SLAC.STANFORD.EDU>
Date: 23 Apr 91 01:49:14 GMT
References: <27006@hydra.gatech.EDU>
Organization: Stanford Linear Accelerator Center
Lines: 46

The real problem with IBM 327x terminals is that they don't run on a serial
(RS-232) line, but on coax. That's nice, because it's fast. It's also a pain
because there is no hardware for an Amiga to use the coax line. So it's no
use to just "emulate a 327x terminal". So what do people do?

First, you can go to a PC (or a Mac?) and buy the appropriate hardware to
sit on the coax line. For PC's I believe one such thing is called an IRMA
board. You then use the 3270 emulation software that supports such a board.
For the Amiga this is currently not an option (as far as I know) unless you
have a 2088 or 2286 Bridge card.

Secondly, you could connect to the IBM through a protocol (it's spelled
protoCOL, folks) converter. Typically these have coax (or something) on
one side and RS232 on the other, and plenty of smarts inside. They usually
do complete protocol conversion inside the box, and do *not* require you
to look like a 327x terminal. In fact they usually support a large number
of different terminal types, and with such a thing you could use any
terminal emulator on the Amiga you like. Most IBM mainframe installations
have at least one of these things, if only for dial-in lines: if you can
get to the mainframe by modem, you go by definition through RS232 and therefore
through a protocol converter (although there may be "cards" for IBM mainframes
that have modems on them and expect something weird, I don't know). Talk to
your system manager about this. A lot of IBM installations have done away
with 327x coax entirely and use protocol converters with terminal
concentrators and multiplexers.

Thirdly, you could connect to the mainframe over Ethernet, using the TCP/IP
Telnet protocol. This works, but with a "regular" Telnet program on the Amiga
you can only log on to the mainframe in "line" mode. In order to be in full
page mode, you guessed it, the Telnet program must behave in a certain way
and also do a full 327x emulation. For Macs, PC's, VAX's and UNIX such a
Telnet (called TN3270 most of the time) exists. For Amigas it don't. Amiga
TCP/IP from Commodore does come with a regular Telnet and it works with the
IBM in line mode. Of course, it is plain vanilla Telnet, which has none of
the features you have come to love in your favorite terminal program.

This last objection I have pretty much solved. Some future version of VLT
will support Telnet over TCP/IP in one form or another (I have a working
intermediate solution which I don't think I will distribute). The TN3270
part is considerably more complicated, and although I intend to support this
too, this is not entirely short-term.


        Willy.
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Willy Langeveld - Bitnet: WGLP09 @ SLACVM - BIX: langeveld