MVS and Macintosh

Nice friendly dinosaur
Are you gonna bark all day, little doggy, or are you gonna bite?

Mr. Pink: Why can't we pick our own colors? How 'bout if I'm Mr. Purple? That sounds good to me. I'll be Mr. Purple.
Joe: You're not Mr. Purple. Some guy on some other job is Mr. Purple. Your Mr. PINK.
Mr. White: Who cares what your name is?
Mr. Pink: Yeah, that's easy for you to say, you're Mr. White. You have a cool-sounding name.
-- From the movie Reservoir Dogs

Back to the Mac

I got tired of all of the Windows adware, spyware, viruses and worms so I converted back to the Macintosh a number of years ago. Here are some notes for fellow mainframers I took along the way along with some tips to help you.


Note: I use the term MVS generically to mean MVS, OS/390 and z/OS. Some of the information on this page can be used for VM and VSE but I have no access to those systems to verify. Use at your own risk regardless.

Current Setup

After having a Windows machine for my whole career* in Data Processing, I finally have a Mac at work. My setup: * Technically when I started in DP, we had actual 3270 devices but every PC I had at work was MS/DOS or Windows

**I got an 2016 Mac in 2018 because it was sitting in inventory of my local PC guys and didn't cost anything to get.

TN3270 to MVS

TN3270 is the terminal application that talks to IBM mainframes. I want my 3270 emulation go "above and beyond": There are many Windows products such as IBM's PCOMM and my company's standard: QWS3270. I haven't found one on the Mac yet...

Freeware products:

Commercial products:

Using Microsoft Windows on the Intel Mac for 3270 emulation:

Now that the Macintosh uses the same CPU as does Windows, running Windows on the Mac Desktop is very easy and runs at almost native speed. A couple of products that allow you to do this is:

  • Parallels Desktop - This is the one I used back in 2013 because it was the first one available.

    To the right is a picture of IBM's PCOMM 3270 product running in Windows/XP on the Mac Desktop using Parallels Desktop:

  • VMware Fusion - This is the product I use now (November 2018) because it is the only one on the approved product list where I work.

(click picture for larger desktop picture)

Tip: Exposé

The first time I used tn3270 on my Mac, I ran up against the Mac OS X Exposé use of function keys which conflict with mainframe applications like TN3270 also using the same keys.

Another tip from Jay Maynard is to change the Exposé key settings using System Preferences (off the Apple in the upper right hand part of the screen). Change the Exposé keys to require a modifier key like the command key and tn3270 will work as expected and Exposé will be available also.

I change the Exposé preferences after each Mac operating system upgrade to not use the ones that I use in TN3270.

See the screen on the right:


New :: [2018-11-11] Apple decided to remove the FTP line commands in High Sierra. I understand that they are not as secure. I followed these FTP line command install instructions. I only use the line mode FTP inside the corporate firewall: Mac to Mainframe.

Freeware FTP

The freeware FTP program I use is FileZilla. It seems to understand the z/OS file structure.

Filezilla is also available on other platforms like Linux and Windows.

Commerical FTP programs:

There may be others but I have heard that the commercial Macintosh application called Fetch which is mainframe friendly.'
What follows is information for 2013 FTP problems: Mac OS X includes a line mode FTP command. To use it you need to open the Terminal application. The syntax is:
ftp mvshost
--prompt for MVS userid--
--prompt for MVS password--
FTP commands here like cd get put quit


If you find that your FTP session hangs when you do use the "dir" or "ls" commands like:
ftp> dir
200 EPRT request OK
Enter these two commands right after your password at the "ftp>" prompt:
  • epsv4
  • passive
Hopefully you will find that the directory commands work as expected now. These commands are needed because the mainframe FTP server doesn't currently recognize EPRT and PASV commands so we tell the Mac FTP client to use the old PORT command.

I see that Leopard (Mac X 10.5) says "Entering Extended Passive Mode" on a PUT so maybe it has more smarts now. I haven't had to manually use those commands in a while.

Rexx on the Macintosh

If you are a programmer, you may be using Rexx on MVS and of course want it on your Macintosh. Rexx runs on just about every platform and that now includes the Macintosh in Mac OS X.

To install, go to the Regina Rexx web site -> Regina -> Downloads and download the ppc version of "Regina". Currently this is a StuffIt file that contains a dmg file. Once the Regina folder is mounted on your desktop you can install it like any standard Macintosh OS X application. Sweet!

In the past I have installed Patrick McPhee's RegUtil on the Macintosh and used it successfully with Regina Rexx. RegUtil enables a lot of operating system functions you have have used on OS/2 like getting directory listings.

Run MVS on the Macintosh

Check out Hercules which is an open source software implementation of a mainframe capable of running many mainframe operating systems.

Run Tritus (SPF editor) on the Macintosh

Read my Tritus Mac Installation page.

IBM Manuals

Read my IBM Manuals page.

Terminal (for Unix Commands) New :: [2011-04-09]

The Mac comes with a Terminal program (like the MS/DOS shell on Windows).

I change the appearance of this screen to be more mainframe-ish using the Terminal application Preferences. The Homebrew option has a nice black background. See the screen on the right for the Preferences dialog example:

Also in Preferences, you can also select the Window button and change the number of rows and columns. I run with a 44 rows and 132 columns (although shown below smaller for this web page).
The ".profile" file that is in your home directory can be changed to customize the Terminal Shell and mine has this customization:
  • Change the command prompt to have the current directory and a nice ISPF-like arrow.
  • Change the output colors so different entries in the directory (ls command) stand out.
  • Add a command called dir.
Here is my ".profile":
# (do not remove this comment)
echo $PATH | grep -q -s "/usr/local/bin"
if [ $? -eq 1 ] ; then
    export PATH
# colors
export CLICOLOR=1
export TERM=xterm-color
export LSCOLORS=gxgxcxdxbxegedabagacad  # cyan directories
export PS1="\n\[\t - \d] \w \n===> "
alias dir="ls -al"
See the screen on the right:

Tip: You can easily get into a directory in the Terminal application using the GUI drag and drop. First type "CD " at the Terminal prompt, then drag the directory from the Finder and drop it on the Terminal window.


This page focuses on the Mac but iPad can also be used for mainframe work.


Apple's Books app reads IBM and vendor PDFs fine. To load them on your iPad, first get into iTunes on your Mac or Windows machine, and use the "Add to library..." option to import them into iTunes. Then connect your iPad to your PC and the normal iPad sync will load them. Books will put the PDFs in a different category than your other books so they aren't all mixed together.

3270 emulation

There are a few on the App Store.

Programmer's Calculator

A mainframer should have a calculator with Hexadecimal support. Here is a free one.


The advice on this page is presented asis and without warranty. Please research any advice given here and ensure that it will work in your environment. As stated at the beginning of this page, these are my experiences that I'm sharing to help you. I will probably not have time to respond to problem emails. Please feel free to let me know about corrections.

Copyrights, Trademarks and other lawyer stuff:

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Last Updated: 2018-11-11
This web page is © 2013+ by David Alcock. All Rights Reserved.