Alexander Huemer wrote:
>I am new to this list and would like to discuss an idea and ask several
>questions.
>* Did anybody ever attempt to 'talk' to 3270 terminals with something
> different than an IBM mainframe?
Yes, here are some examples of entities that did exactly that:
Amdahl
Fujitsu
Hitachi
The so-called "plug compatible" mainframe vendors, in other words.
IBM itself offered a couple choices that (in my view anyway) are fairly
described as "non-mainframes." The IBM 3790 was one such example, a
"distributed computer" announced in 1975. Many 3790s were connected to
mainframes (IBM and non-IBM), and you needed a mainframe to create programs
for it, but it could (and often did) operate independently.
I found an article written by John J. Hunter and published in the October
6, 1986, edition of "Network World" that describes some other products,
including IBM's own 3174 Subsystem Control Unit that had some interesting
capabilities. Let's start with the IBM 3174, which was available with "an
optional protocol converter adapter that allows IBM terminals to emulate
Digital Equipment Corp. VT 100 and IBM 3101 terminals. It will also enable
the terminals to communicate with Ascii host applications and public data
networks." In other words, you could use an IBM 3174 with this optional
adapter to enable your physical IBM 3270 series (e.g. IBM 3179 Model 1)
terminals to communicate with DEC VAX, PDP, IBM Series/1, and various other
systems that supported at least one of those two ASCII terminal protocols
-- and there were gobs of them in the 1980s. The article alludes to
attaching an IBM 3174 (with IBM 3270 series terminals) to a suitably
equipped IBM PC/AT or IBM RT PC ("local applications-processing facilities
[.] [u]nless personal computers are used....")
The article also describes the directly competing products at that time:
"the ITT Courier 9000 Series, the Lee Data 300/400 product line, and the
Telex 270." The products also effectively turned physical IBM 3270 series
terminals into ASCII terminals. ITT and Lee Data also offered local
processors running the Xenix operating system.
IBM also had something called the "IBM 5209 Link Protocol Converter" which
allowed 3270 series devices to be attached to older and contemporary
System/36, System/38, and AS/400 machines.
>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.
If you can find an IBM 3174 equipped with the optional protocol converter
adapter and the RS-232-C port for a host connection, you should be able to
connect genuine IBM 3270 series terminals to, for example, a PC running
Linux that has a serial port, or at least a USB port since you should be
able to find a USB to RS-232-C "dongle" cable. The ITT, Lee Data, or Telex
equipment described in "Network World" should also work if you can find it,
although I have to believe the IBM 3174 equipment is easier to find.
Bitsavers.org has a copy of IBM Publication GA27-3850 ("IBM 3174
Establishment Controller Introduction") that describes the Asynchronous
Emulation Adapter ("AEA") starting on page 2-2:
http://www.bitsavers.org/pdf/ibm/3174/GA27-3850-0_3174_Establishment_Controller_Introduction_Apr89.pdf
According to that publication the AEA Feature was available for all the
"large" and "medium" 3174 models, but not the "small" 8xx and 9xx models.
For what it's worth, the November 23, 1987, edition of "Network World"
describes another IBM 3174 competitor: the Harris H174-32L Local Control
Unit, part of their "Challenger" line. It too included a protocol converter
to allow IBM 3270 series terminals to "appear" as VT 100 compatible ASCII
terminals to hosts, and it had RS-232 and RS-422 interfaces (plus some
other choices) for host attachment, according to the article.
An Ethernet connection might be trickier to get working than the RS-232-C
interface, although if you can find a single IBM 3174 with both, that'd be
nice. Token-Ring is another possibility, probably also with some protocol
difficulty. It's rather easy to find used PCI Token-Ring adapters and IBM
8226 MAUs. (The IBM 8228 works too, but the unit and associated cabling are
much bulkier.)
As another completely different approach to getting genuine, physical IBM
3270 series terminals working with command line/VT-100-style Linux (as a
notable example), hypothetically you could have one or more such terminals,
any terminal controller required, a genuine vintage IBM mainframe, and
perhaps a bit of custom software running on the mainframe. The IBM
Multiprise 3000 seems like a reasonable choice in this role because it
could itself run (now vintage) Linux, although I think you'll still need a
terminal controller, such as an IBM 3174.
Anyway, net net, yes, it's possible to do what you're describing, because
it was pretty routinely actually done.
--------------------------------------------------------------------------------------------------------
Timothy Sipples
IT Architect Executive, Digital Asset & Other Industry Solutions, IBM Z &
LinuxONE
--------------------------------------------------------------------------------------------------------
E-Mail: sipp...@sg.ibm.com
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