https://www.rs-online.com/designspark/a-fresh-look-at-ibm-3270-information-display-system
The IBM mainframe computer has evolved over a period spanning almost six decades and in part, this has been in response to wider industry trends, with notably the advent of "midrange" and personal computers, and the sweeping success of TCP/IP. However, the mainframe has also been responsible for delivering features and functionality which would only come much later to smaller systems, not to mention enduring and enviable reliability which is hard to beat today.
This post takes a look at the IBM 3270 Information Display System, which played a key role in enabling a single mainframe computer to scale and serve thousands of users. It should also be noted that, while discussing the system mostly in the past tense, the mainframe itself very much lives on and actually so does 3270, albeit nowadays as a protocol that is run on top of TCP/IP.
(Score: 4, Interesting) by atwork on Tuesday February 10, @04:21AM (1 child)
About 35 years ago I worked at a bank that ran hardware Wyse50 terminals as well 3270 and VT100 emulators on PCs. It was a bit of a pain to map the screen commands for each of the terminal types for each of the various forms that users might be displaying. But up stepped the most experienced programmer - let's call him Eddie - who came up with a form-designer that would automatically map a standard form to the terminal type defined for the terminal in question. This was an obvious solution after the fact but an eye-opener for me at the time.
Eddie had moved on by the time we started sending the same forms to web browsers, so I got the pleasure of implementing the HTML form mapping.
Fun times :)
(Score: 5, Funny) by Anonymous Coward on Tuesday February 10, @05:31AM
curses
foiled again
(Score: 4, Interesting) by SemperOSS on Tuesday February 10, @08:45AM
The 3270 protocol specified a continuous connection with short response times to consider a terminal up, which required a constant barrage of are-you-alive? packets (yeah, okay, sort of same as keep-alive packets, but I like the other name better) to be sent when the connection was otherwise idling. This meant that long-haul connections could not be established via traditional modems as an are-you-alive? packet would not have been received by the terminal before the controller would time out for lack of response.
What to do?
The solution was a spoofing box at each end. The one at the controller end would respond to the controller's are-you-alive? packets locally and thus keep the controller happy, while the one at the terminal end would spit out unrelated are-you-alive? packets to keep the terminal happy.
The IBM mainframe environment was (and is) interesting — groundbreaking in many ways — and definitely created a lot of ingenious solutions, most of which are still in use, one way or another.
Open Source Solutions and Digital Sovereignty is the new black
(Score: 2) by VLM on Tuesday February 10, @02:54PM
Its a really good bottom-up article. Cool!
From a top down perspective, if you like MVS and Hercules retrocomputing, try KICS a mostly source code compatible a FOSSish replacement for CICS
https://www.kicksfortso.com/ [kicksfortso.com]
https://www.jaymoseley.com/hercules/kicks/index.htm [jaymoseley.com]
https://github.com/moshix/kicks [github.com]
and probably many other sites.
There are obvious inherited ideas and traditions between the modern web CGI etc and CICS.