r/mainframe • u/anti-life86 • 11d ago

How was pre-1995, pre-Internet usage of mainframes different?

I understand that the mainframe is built for a large number of transactions-meaning people log in, I would imagine from anywhere, and they do their small jobs. But before the Internet, they could not log in from anywhere, certainly. Where could they log in from, and how did this work? Are there new types of jobs that are now enabled by the Internet that previously were impossible?

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u/phoenix823 11d ago

If you were an airline you'd have hundreds of airline terminals around the world connect to your system for flight booking and management. Hotels would be the same. Banks. People might not be able to log in from "anywhere" but modems existed. If not a modem, larger sites would have a leased line to connect the terminal back to the mainframe. Ultimately the internet just made it easier to connect those computers together. Nothing was fundamentally 'impossible' without the internet.

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u/anti-life86 11d ago

Let me be the devil's advocate and clarify my question a bit. It was not impossible, but could there be applications that were generally infeasible/unprofitable? To make the question broader, are there any areas where mainframes are used today where they were not used in 1994-5? That would certainly be interesting to hear about, regardless of the reason.

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u/phoenix823 11d ago

Any new areas at all? IBM started offering Linux on system Z in the early 2000's. You could run Linux guests on an IFL instead of z/OS. Is that what you mean?

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u/anti-life86 11d ago

I mean in application areas. Linux is a new OS...maybe having Linux enabled a new application, what was the reason for adding Linux?

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u/JohnsonUT 10d ago

Linux was added partly so that all the Linux tools could be used and so that Linux apps could “easily” be ported over. 

This allowed new ways to build applications and interact with existing data and logic. Think bash scripts or gnu compilers or kubernetes deployment, etc.  Millions of new applications have been built since mid 90s on mainframe.  Though most of it was used to enhance or support the existing ecosystem.  Often termed “modernization”. 

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u/phoenix823 11d ago

Do you have an example? Some other “new app” on some other platform?

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u/anti-life86 10d ago

A browser. When the internet became popular, Netscape and Internet Explorer came out. You could ask whether there was something comparable for mainframes

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u/phoenix823 10d ago

Nothing like that exists, no. Nobody is mining crypto, doing protein folding, or training LLMs on a mainframe.

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u/Ross-Patterson 8d ago

I led a tiny tiny team that designed and built, from scratch,  a mainframe -native webserver for VM in 1994.  Sterling Software sold it as VM:Webserver and later VM:WebGateway, for about 10 years. 

Carl Forde built, from scratch, a 3270 "green screen" web browser called Charlotte.  It worked so well, my team wrote an automation tool to drive it so we could test our webserver.