You can! You need to install the Hercules mainframe emulator and the freely available MVS 3.8 on top of it. There are compilers for COBOL, Fortran, PL/1 and assembly available. The go to guy on YouTube for getting all this working is moshix:

https://www.youtube.com/c/moshix

How close is it to the real deal in emulating something like a modern mainframe?

Very close to the real deal only when emulating a 370 from the 80s. zOS is a different beast though even though it shares a lot of the asm underneath. But there is no way to run zOS for yourself without a license from IBM or access to a real z-series somehow.

Kinda what I figured. Th whole concept of a mainframe is pretty neat in that you can go through the 1000 page manual and have an idea about all that is possible, instead of an infinitely changing software tool ocean. The latter is probably better overall, but it would be neat to check out the mainframe paradigm.

Running z/OS on Hercules is trivially easy, you just need to ignore the license. The z/OS software distribution is usually called ADCD.

Yeah, I'm only interested in using software legally, but it's a shame IBM doesn't make this available. It's not like someone is going to just port all their mainframe apps to run on this emulator right? Or is that a real concern of theirs? I figure the hardware itself is the secret sauce.

I get the impression (as a vaguely interested outsider looking in from a distance and making a LOT of presumptions) that it's "just" institutional drag and "tradition". Create a culture founded upon filling in forms and ticking boxes, and "hi I can haz?" is going to produce $every_windows_error_at_once.wav, a lot of hand-wringing, and an internal processing chain that'll naturally tumbleweed itself in the general direction of the legal department. Network effects / emergent behavior. Soo, you read between the lines ("ah, it's fine, the requirement was fulfilled"), and take it from there. 𝙻𝚘𝚐𝚘𝚗 ===> _

The only reason I haven't pursued this myself is that MVS is ultimately just not objectively compelling enough, because while it's similar to what's out there today, I get the impression I'd only have to unlearn an arbitrary bunch of things once I was on the "real" system.

As an aside, I happened to stumble on a copy of "IBM and The Holocaust" a few years ago. It's a startling insight into IBM's beginnings tabulating and wrangling data on the millions of Jews "processed" throughout Germany in WW2, which turned out to be the first commoditized consumption of what would today be regarded (without a second thought) as big data.

The world has certainly moved on since that point and IBM's DNA is completely different today, but IMO the "data processing" energy still remains as an incredibly strong centerpoint, and I honestly see mainframes as a digitized realization of the punched-card concepts IBM's beginnings were founded upon. (Combined with the institutionalization aspects I hinted at in the first paragraph, this is the main reason I'm very hesitant I'd survive in what sounds like an especially rigorous environment.)

While the UI of reading a printed book hasn't yet been beaten (I'll switch to e-readers once they can pageflip instantly -.-), it's very practical to be able to virtually pick up a book and thumb through any portion. To this end, PDFs of this title seem to readily be floating around, for example (open as URL) data:text;base64,aHR0cDovL3Bvc29oLnJ1L2Jvb2svaHRtL2libS5wZGY

I will note that after reading I kinda looked askance at my ThinkPads a bit and went "wow, what a history. uhhh....". Fair warning :)

I should have said 'legally'.

I used to fix compilers for IBM and we worked on (older versions of) these machines. They were awesome! Coming to the PC business after using mainframes was a sad joke. You should see what it's like working with VM, IBM's virtualization environment. It was amazing and that was 25 years ago.

It is so stressful and alienated that the decades spent on mainframe is good but not great. I worked on the partition Management called lpar. Os and db2 etc. It is sort of more interesting to do dos/vse. I guess instead of thousands of users you have hundreds.

I love my Hp 200 dos calculator whilst waiting for the cartridge to run, … at least it is not open reel tape as the cartridge tape at least always suck in.

It’s interesting that IBM wasn’t sooner to the cloud with superior virtualization technology.

Just like the PC, they didn't realize it was important until it was too late. In my experience, mainframes are a superior way to develop and run every kind of software. The PC is a crippled, stupid stepchild by any reasonable comparison. Just the idea that you need to setup and manage 1,000 of them to come close to a small mainframe is ludicrous. Who needs the overhead and maintenance? Sure, you can swap machines and distribute loads between them, but who wants to? Yuck. It's a lot nicer to have that stuff handled automatically.

Also like the PC, IBM didn't realize that their boxes could be used for this new funky thing called the internet. Talk about blind-sighted. Their first web product was an abomination they inherited from their purchase of Lotus. It didn't work and produced unusable websites, boding poorly for IBM's entry into that market which was already taking off with Active Server Pages and XMLHTTP.

If IBM had loudly (and correctly) proclaimed that mainframes were the place to run web services, everyone and their mother would be running mainframes right now instead of Linux boxes. IBM's eventual realization of this led to their purchase of Red Hat!

> If IBM had loudly (and correctly) proclaimed that mainframes were the place to run web services, everyone and their mother would be running mainframes right now instead of Linux boxes.

No, they wouldn't. I could take one Linux box, get a domain name, and have a web server. I wouldn't be able to afford a mainframe, though. And if your alternative is renting a fraction of a mainframe, the answer is no. No, I will not trade a Linux box that I control for renting a piece of a mainframe that I don't control. Just no.

For enterprise is what I meant. Not for individuals.

Well, not just mainframes generally, but if they created AWS on mainframes and hosted them… that would have made it accessible for startups.

It was so simple internally, they could have ported those tools to a GUI. But GUI's and user interfaces are not something IBM has ever done well (other than command line ones).

The organisation is also in the way. Both in Ibm and for those teams using ibm. Very bureaucratic and like token ring over management kill. Good and have its niche. But murder by the liberal Ethernet.

I would argue neither has AWS yet…

The most logical place for a cloud service to develop inside IBM would have been IBM Global Services. IGS had a sort of proto-cloud set up in 1998-1999 (treated physical systems as cattle that could be remote wiped, virtualization would have been a logical next step) but sold off the organization building that to AT&T as part of the Global Network sale.

I wrote a horrible, hacky, CMS PIPES based gopher/http server for VM some time in 1993 that was used internally for various "non serious" things. A colleague and I designed a native HTTP server for MVS in 1995 and had started coding it when we were more or less reprimanded and told to defer to the then Network Services division which was porting something (I think CERN httpd, they had a bizarre fascination with CERN) to MVS.

It just wasn't in anyone's best interest to even experiment with web services on VM or MVS, let alone try to build a business out of it.

Cloud happened after I left, but the infrastructure to build or respond to the rise of AWS was never in place, sort of by design.

Sidenote: In VM, you could spawn a new machines with "physical" storage or drives (Nothing was physical on the mainframe; everything is faked just for you! Awesome.) by typing a single command at the command prompt! If you needed to fix a bug in some combination of operating system and IBM products, you could spawn that exact customer-replicating environment in about 2 lines of text.

Try that with Kubernetes!

LPAR makes LVM a joke.

It's sad to read about the dev headaches caused by today's poor virtualization environments. I distinctly remember that stuff was no work at all at IBM. It didn't interfere one bit with the actual work of coding on the products. In fact, we really never thought about setups or creating environments for testing or development.

In peer reviews, for example, it was standard to bring output from both the failing case and the working case as printed handouts. Those were easy to generate; just spin up two machines and fix one while you leave the other broken. They can share resources if you like so you don't have recreate everything. That is horribly messy today. Testing is so hard most people don't do it.

Also on simpler BSD's like OpenBSD, bioctl is dumb simple. Setting up a encrypted disk is a no effort task.

On firewalls, PF has a syntax simpler than most text adventure games.

Every time I get into the GNU world, well, I get better HW support sometimes, among a slight bit of performance, but, FFS, configuring a Linux firewall gives me nightmares everyday. Just compare NAT on Linux vs OpenBSD. Or TUN/TAP devices, where in OpenBSD it's just a matter of a SINGLE line at pf.conf and two hostname.if files to define the bridge and the tap device with a subnet. Done. Oh, and sysctl to set IP forwarding, but that was the easiest task on any OS.

In a sense, a parallel sysplex with remote hosts and storage is a very sophisticated private cloud environment that'll run your CICS transactions a lot like you do with AWS Lambda.

IBM has a event where you can get access to a mainframe and complete different tasks https://www.ibm.com/it-infrastructure/z/education/master-the...

You can also get free access to small vps running Linux on a mainfram on the IBM cloud

> You can also get free access to small vps running Linux on a mainfram on the IBM cloud

What's the point? VM with linux is hardly interesting to anyone.

Amusingly, I signed up for this a couple days ago (https://mtm.masterthemainframe.com/), which worked fine at the time, but the following day when I went to follow up I discovered the HTTPS cert had expired :D

That was several hours ago. The site's still down.

UPDATE: THE DOMAIN EXPIRED HAHAHA

Archive link: https://web.archive.org/web/20210729160256/https://mtm.maste...

Update-update: Bureaucracy, Inc™ has belatedly noticed and exercised untold power to bring the domain back in a great hurry.

Everything's back to exactly how it was before, even down to using "" (ie, empty string) where my name should be. Excellent.

I must say that site responsiveness is much, much slower than it was when it was serving spam. :D

That is pretty amusing, I also just received a mail from them telling me that my opinion was important to them. Heh

I used it when I was doing some porting of smaller programs to run on z/Architecture for example setting up the de/compression co-processor correctly. It's true that Linux on x86 or arm is not unusual, but this is Linux on Z

"Sounds like it would be fun."

Interesting at times but really really not fun

Interesting to me is a big part of the fun. Learning something new...all that.

Well "to do mainframe development" is more than just the casual learning part.

Touche'