What is the best IBMi (AS400) 5250 Terminal Emulator?

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August 31, 2015

The IBM i System (aka i5 aka iSeries aka AS/400) uses something called 5250 to stream its data to a terminal, often called a green screen. You’ve seen this clunk old terminals in black and white scifi movies – well we still use them. Kind of. But we use a terminal emulators (software which emulates the functions of those old terminals) to type commands into a command line interface using windows/linux/mac whatever.

If you are trying to connect to an i5-iSeries-AS/400, you probably want a telnet client that handles 5250. This is called a TN5250 client.

Before we get the to the free stuff

My 5250 Emulator of choice is Mochasoft

This is a commercial product but looks nice and I’ve used it for years. It works with every version of windows and does exactly what it says on the tin. It’s lightweight and simple to use so checkout (https://www.mochasoft.dk) for their TN5250 client. At time of writing it is $25 per client.

Me. Just Now.

Having said that – We all love free stuff right?

Free 5250 Emulator

Sourceforge has a true open-source, freeware TN5250. You can download it and learn more at tn5250.sourceforge.net It is small (less than 1 mb) and installs very quickly…. and it’s #free.

I suggest two configuration changes to make:

After installation, you should have a desktop icon named TN5250.

Right-click on that icon and then click on properties. Add the characters


Now we can create a config.file to store our most used connection info. Use the MS-DOS editor to create a new file called tn5250rc by typing:

edit tn5250rc

Set all of your TN5250 options in this file. For example, if you wanted to create a display called FRED1 which
connects to an as400 called iseries.sample.com, you’d type this:

profile1 {
host = iseries.sample.com

Now that you’ve created this, you can utilize those settings just by typing:

tn5250 profile1

Be careful of capitalization. “profile1” is not the same as “Profile1” and that’s different from “PROFILE1”.

You can set any of tn5250’s settings in the tn5250rc file. Here’s a more sophisticated example:

profile1 {
 host = ssl:iseries.sample.com

profile2 {
 host = ssl:as400.example.com

printer {
 host = ssl:as400.example.com


(that is an underscore chracter between “+resize” and “fonts”) This will allow you to resize the window.

In the folder “Program Files” in the sub-folder “TN5250” is a file named “TN5250rc”. (C:\Program Files (x86)\TN5250)

Change it (one way is to right-click, selct open-with and select notepad or Wordpad)


Terminal Emulator TN 5250

Make it look something like this:

font_80=MS Gothic-12x24

(Instead of, enter your host ID or TCP/IP address)

The font_80 line changes the font to MS Gothic and the 12×24 defines the width and height of the window. Change those until the window is the size that you like.

That’s it. Double-click the TN5250 icon and you should see an i5-iSeries-AS/400 display terminal session.

This application is very full-featured. It also includes a Linux version.

Go to TN5250.sourceforge.net to learn more.

UPDATE 2020: Download Free 5250- Emulators

Read my latest review of 5250 Emulators and how to download other free Emulators here



IBM i Software Developer, Digital Dad, AS400 Anarchist, RPG Modernizer, Shameless Trekkie, Belligerent Nerd, Englishman Abroad and Passionate Eater of Cheese and Biscuits. Nick Litten Dot Com is a mixture of blog posts that can be sometimes serious, frequently playful and probably down-right pointless all in the space of a day. Enjoy your stay, feel free to comment and remember: If at first you don't succeed then skydiving probably isn't a hobby you should look into.

Nick Litten

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