What can I do with a personal mainframe?

May 15, 2017 8:52 PM

I'm asking half-jokingly, as I've a thing for retro-computing as a hobby. I recently rediscovered the Hercules Emulator, and have set about trying to learn how this kind of computing works.

I grabbed a copy of MVS, and have decided to also take on the Master the Mainframe contest, even though I'm just learning and not actually competing.

Does anybody have thoughts from similar projects? Does anybody in the hive mind actually work on these things? Am I wasting my time?

posted by Alensin to Computers & Internet (7 answers total)

I don't know, but here's a guy that bought a z890 for a couple hundred bucks, but then he needed adaptors and disk drives and such. His total outlay was three or four hundred bucks.

I might run APL on it so I could run a model of a System/360.

Some say that %70 of business transactions still run in COBOL. And Fortran is still huge in climate modelling and other scientific computing.
posted by at at 11:40 PM on May 15, 2017 [1 favorite]

RPG is also still surprisingly widely used for legacy business programs. That's probably the entire reason IBM still sells AS/400s. I've seen some pretty high wages offered for folks who can maintain those old programs. I'm fairly sure the bigger systems emulated by Hercules also support RPG, so it might be something to look into.

It's definitely far more "out there" relative to other languages than COBOL or Fortran. Less so in its latest version, but it still doesn't stray far from its punch card origins.
posted by wierdo at 1:39 AM on May 16, 2017

"What happens when an 18 year old buys a mainframe?" might interest you. He bought a physical machine - so the initial part of the presentation deals with the practicality of how to fit the thing in your basement.
posted by rongorongo at 4:20 AM on May 16, 2017

There's an old text book "Operating Systems" by Madnick & Donovan which (I can't remember) contains an operating system for a 360 or teaches you to write one. Probably both.
posted by Obscure Reference at 5:00 AM on May 16, 2017

Owning a mainframe is like buying an old fire truck. It's cool to show it off to people, but it takes a lot of room, uses a lot of energy and is not really fun to use.
posted by leaper at 8:39 AM on May 16, 2017 [1 favorite]

You could use it to learn assembler. My college (in the mid 1990s) used System/360 assembler* as its teaching language. I don't know how true this is but the instructors stated that 360 was used because despite its quirks it was simpler and more regular than x86 assembler and slightly more high level and thus easier than using a chip that RISC based.

*The System/360 was actually an emulated environment running on a VAX/VMS system.
posted by mmascolino at 8:39 AM on May 16, 2017 [1 favorite]

Funnily enough, I've just started trying to recreate the computer setup used at MIT to teach A FORTRAN Coloring Book, so most likely something late 1970s IBM-ish.

I've been emulating minis for quite a while with SIMH; PDP-8 is particularly fun, since it's such a tiny, tidy system.
posted by scruss at 4:20 PM on May 16, 2017 [2 favorites]