A customer who wanted to discuss mainframe interop phoned up one of the MS Business Managers yesterday and the query got routed through to me. Most of the technical people in Microsoft are nervous about mainframes but I love them which is I guess why the mainframe work tends to come my way. I like mainframes so much because I pretty well grew up with them so they are very familiar to me.


I got into computing because I was in Iran working on the telemetry systems for a gas pipeline and really enjoyed working on the control panels in the operations centre which was in the south of Tehran. When I left Iran after a lot of adventures (remind me to tell you about the WW2 Luftwaffe pilot in the Company Helicopter!) and returned to England I really wanted to get a job with lots of light and switches just like the telemetry control system.


In those days mainframes were covered in lights and switches and so I applied to IBM for a job. The first couple of years I sent hours on the 360 mainframes setting up the hex rotary dials to input my programs and then reading the results off the register lights. Things got a bit more difficult on the 370’s as they took a lot of the lights off and put on a keyboard but then the 3090 came along with a monitor. This was the end of my lights and switches love affair (until the Altair!) and so I had to learn how to type hex into the 3270 screen, set up the PSW and CCW and hit the run key on the keyboard. Suffice to say when you have typed hex into a system they lose much of their mystique.


Nowadays most of my mainframe work is around CICS and whilst I wouldn’t say I was an expert I was in IBM Hursley (home of CICS) for 17 years and some of it rubbed off. I do enjoy working on the interop with these systems, they are actually pretty simple it’s just all the acronyms are different; SNA, LU6.2, SDLC, APPC, VTAM, VSAM, KDS etc. If you know what they mean you are most of the way there and as I used to do test on SNA and 3270 / 3704 controllers I know them pretty well. Incidentally I think that starting off in test gives you a really good grounding in the IT and if it’s hardware test you get to play with lots of big and cool test rigs. One day I will write a Blog on tricks you can play with an Environmental Chamber.


The key thing with working on mainframe systems (I hate the term legacy) is to sound knowledgeable enough so that the customer goes and gets the sysprog who understands how the system works. It’s amazing but there is generally only one person in an organisation who really understands how the mainframe is configured. If you can get hold of him then it becomes much much easier.


First of all though you have to be sound creditable enough that they will get the sysprog guy and as it’s a while since I did any CICS work I need to do some homework, especially as some of the programs the customer is using I am unfamiliar with, so I have been boning up on mainframe systems for the last couple of days. I’ll write up some of this tomorrow.

Comments (7)

  1. Greg Robinson says:

    I didn’t see JCL in there anywhere 😉

  2. Michael Platt says:

    Ah, JCL was really from a pre TSO era although I know it is still iin use (a lot!), all the acroyms above come from TSO and later. I still think of JCL as the new fangled thing that replaced HASP.

  3. donAT (DonXML Demsak) says:


    You might be interested in my posts:

    Life as a Reformed Mainframe Programmer in the .Net World


    My First Declarative Programming Experience – JCL

  4. Brian Keller says:

    Great post – I know what you mean about how rare Mainframe knowledge at Microsoft is! Prior to joining Microsoft I worked for Barr Systems – – doing PC-to-Mainframe connectivity. Lots of SNA/HIS Server, channel printing, etc. I started there when I was 20, which was kind of weird considering that most people my age who are quite computer savvy have no idea what SNA architecture is like. <g>

  5. Michael Platt says:

    Interesting posts, I agree that CICS and MTS are pretty similar and that JCL is declarative.

  6. Torsten Kramer says:


    if you’re interested in mainframes or if you want to revive the ‘good old days’ take a look at There is all you need to run a *real* MVS 3.8 system on your Windows or Linux box. Cool.

  7. Michael Platt says:

    Interesting. When I worked at IBM they used to sell off old kit at so many $ per kilo, a guy I shared and office with bought a 370/168 and put it in his garage where he used to use it as a "PC"!

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