[Info-vax] OpenVMS async I/O, fast vs. slow

[Jake Hamby (Solid State Jake)]

On Monday, November 6, 2023 at 5:51:47 AM UTC-8, bill wrote:
> > 
> > I have never seen another legal way of gaining z/OS experience for free 
> > (although a _really_ old MVS version is legally available for free). 
> >
> z/OS is not the only mainframe. I have UNISYS OS2200 running on this 
> PC just like the VMS Student Edition. 

You downloaded the free UNISYS OS2200 system? I looked at that, and the Burroughs MCP emulation that UNISYS also sells, and decided those systems were far too old and weird for me to spend time on. VAX and System/360 may be old, but at least they used 8-bit bytes and two's-complement integer arithmetic.

There was going to be a hobbyist version of the ZD&T test environment, which is IBM's official emulator solution for z/OS development. It runs on 64-bit Linux. I paid the $160 or whatever the fee was, and then I got some emails from their sales people and then nothing. Apparently they had some change of plans and they switched from USB license sticks to cloud license keys and I may have gotten lost in the shuffle. Their website mentions the "Learners Edition" but it's been scrubbed from the main sales page. I'll have to send some emails to see what happened.

It was my interest in getting access to the "Learners Edition" (IBM only wanted to sell it to people with either professional experience with z/OS or who demonstrated mastery by doing the Z Xplore program and the z/OS Mainframe Practitioner badge, which is difficult!) that led me to learn as much about it as I did. Data sets are annoying!

A third option is paying to set up your own z/OS system in the IBM Cloud. They'll give you a free usage credit of $700 or $1000 or something like that, and then you can use that to mess around. Of course you have to delete everything so you don't get billed.

I believe the IRS has some OS 2200 systems somewhere (the vast majority of their work has been done using IBM and HLASM, not COBOL, which is why it's been so difficult for them to modernize it), because their coding standards page mentions it as one of the assembly languages they use, specifically:

UNISYS ClearPath OS2200 Meta-Assembler (MASM) Programming Reference Manual Level 6R3J
UNISYS ClearPath OS2200 Executive Control Language (ECL) and FURPUR Reference Manual

https://www.irs.gov/irm/part2/irm_02-005-003

Regards,
Jake Hamby