Thanks for the link, Chris.
I happen to have a GX20-1878-3 (October 1978) 3270 Information Display
System Reference Summary in the top drawer of my desk. It shows the screen
size of a Mod 1 as 12x40, although I never worked with a Mod 1 or ever even
saw one, to my knowledge.
My first 3270 data stream experience was with a Mod 2 in 1976. I did
something similar to the classic "Hello World" application, but it was
acctually a calculator that supported two operands and the operators +-*/.
By sometime in 1977, we had a homegrown 3270 based transaction processor
affectionately called "TP" which was similar in overall function to CICS (of
that era), but nowhere near comparable to CICS as far as features.
The channel attached control units for those 3270's were notorious for
generating interface control checks, which the operating systems of the era
(OS/VS1, SVS, and MVS 3.8) were notorious for responding by entering
disabled waits, resulting in many unscheduled outages, and this seemed to
persist into the early 80's.
The last time I used the GX20-1878-3 was probably 1989-1991 when I was asked
to see if I could write a number of user exits to a product called Verify
(then developed and owned by Online Software International -- later acquired
by CA, and I believe retired, although an incarnation of it for VTAM might
still exist), which was an early regression tester for CICS. Verify had the
ability to record input 3270 data streams and output 3270 data streams from
a series of transactions, and "rerun" them later, presumably after system
changes were made. There was a compare function to see if the same output
resulted before and after the changes -- regression testing. We didn't use
it that way, though. . .
...The task was to drive CICS transactions with input data from flat files
(QSAM), record the output in flat files, and respond with some level of
intelligence to whatever output from the transaction was. This required a
lot of dynamic file allocation and OPEN, GET, PUT, and CLOSE -- stuff one
is not supposed to do in CICS-- and precise 3270 data stream interpretation
and manipulation, and there was the need for GX20-1878-3. A couple of big
SW vendors were approached about this and passed on the opportunity before I
was contacted. Later, there were even people who told me and others closely
involved "You can not do that using Verify." after I had already done it!
Not really relevant, but the application requiring the Verify work was a
very industry-specific accounting application (something like mining --
multiple landowners, etc.) that had been developed with the help of one of
the big accounting firms. The customer needed to migrate data from several
disparate systems to their new application which was CICS/DB2 based, so this
creation served to:
1) stress test the new infrastructure (and stress the infrastructure it did,
with a near zero user think time),
2) test the new application code, and ...
3) facilitate the data migration from the older disparate systems to the new
one.
Larry Chenevert
----- Original Message -----
From: "Chris Mason" <chrisma...@belgacom.net>
Newsgroups: bit.listserv.ibm-main
To: <IBM-MAIN@bama.ua.edu>
Sent: Thursday, November 10, 2011 7:41 PM
Subject: 3270 archaeology (Was: TSO SCREENSIZE)
To all actually interested in 3270 pre-history
And the original IBM 3270 screen size was Model 1, 12 lines by 40
characters. Model 2 (24 * 80) didn't come along until later.
It was my possibly faulty recollection that just about all of the first
generation of 3270 equipment was announced - and, I'm going to guess,
could be delivered - in one go.
By resort to comprehensive Googling, it is possible to avoid dubious
speculation - because I found the "smoking gun" - and I also found the
page which is indeed phrased in such a way that it could be
misunderstood.[1]
By entry of the following:
history 3270 IBM
the 26th "hit" (3rd page) is the following manual very kindly retained for
us by "bitsavers":
"An Introduction to the IBM 3270 Information Display System", GA27-2739-1,
Second Edition (May 1971)
http://bitsavers.org/pdf/ibm/3270/GA27-2739-1_An_Introduction_to_the_IBM_3270_Information_Display_System_May71.pdf
or the 4th item on the following page:
http://bitsavers.org/pdf/ibm/3270/
I draw your attention in particular to the "-1" at the end of the "form
number". Unfortunately this isn't "-0" but literally the next best
thing.[2] You will note the following in the "Preface":
<quote>
. 3277 Display Station, Models 1 and 2
</quote>
and the fact there are *no* revision bars. That means that this bulleted
list item was the same in the previous edition of the manual, the "-0",
and that, because of the date and, unlike another manual I unearthed
(GA23-0060-0, November 1980), this is not some reissue of an earlier
manual. Therefore the Model 1 and the Model 2 were described initially at
the same time and I am going to assume they were announced at the same
time, approximately the date of this manual.
-
[1] The 5th "hit":
http://www.hob-techtalk.com/2008/09/12/3270-a-brief-history
<quote>
The first display had a very small screen displaying only 12 rows with 40
characters.
</quote>
A bit of a sort-of "Chinese whisper" problem here. I think this "first"
need not *mean* chronologically although that is implied.
[2] Fortunately I've just finished reading "Tinker, Tailor, Soldier, Spy"
and so I have been tuning my deductive reasoning! I don't believe I had
actually read the book before but I - tried to - follow carefully the
7-episode BBC series 30 odd years ago. I don't believe the film can
possibly do justice to the complexities or the sequencing of the
revelations.
Another interesting point is that the BBC series included a key scene near
the end which is not explicit in the book. I wonder what the film will do
...
-
Chris Mason
On Thu, 10 Nov 2011 15:15:25 -0600, Mike Schwab <mike.a.sch...@gmail.com>
wrote:
...
And the original IBM 3270 screen size was Model 1, 12 lines by 40
characters. Model 2 (24 * 80) didn't come along until later.
--
Mike A Schwab, Springfield IL USA
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