Games
Groovy MiSTer Install Guide
This is a quick step by step for getting up and running with Groovy MAME and Groovy MiSTer, which connect a PC to the MiSTer FPGA platform for faster, more authentic gameplay on a CRT display. This setup effectively bypasses the video system on the PC end, shoving the pixels over the LAN to the MiSTer, which does a great job supporting CRT displays with very little lag.
The overview is simple: a compatible emulator on the PC is set up with the Groovy MiSTer module, and a new program runs on the MiSTer, receiving the video and audio, and sending control inputs back to the PC.
Setting it up is very simple if you know a little bit about stuff, and this guide assumes you know how to edit some text files on both the PC and the MiSTer.
Executive Summary
- MiSTer: Add two files to the MiSTer and add two lines to a config file
- PC: Download Groovy MAME and swap in the new config file, edit it to point to the MiSTer’s IP address
- Groovy MiSTer: enable controls and sound
Step One: Install Groovy MiSTer
This software was created and updated by Psakhis (Sergi Clara), until their death in 2024. They championed the idea and made it work.
First, download two files from the Groovy MiSTer release page:
- Groovy_20240922.rbf
- MiSTer_Groovy (no extension)
The RBF file is placed on your MiSTer under one of the main underscore categories: _Arcade, _Console, etc. The general recommendation is to put it under _Utility, which makes it easier to find, if nothing else.
/media/fat/_Utility
The other file is effectively a replacement for the core MiSTer code, and should be copied to the root of the fat directory on the MiSTer:
/media/fat/
Some older guides will have you renaming this file, but the latest release does not require this.
The last step is adding two lines to the .ini configuration file. If you have more than one .ini file, you should add it to them as well. It tells the MiSTer system to use the alternate core when Groovy MiSTer is launched.
[Groovy]
main=MiSTer_groovy
That’s it! Just copy the two files, edit the config file, and your MiSTer is ready to go.
Step Two: Install your Emulator
For this guide I’m only going to cover Groovy MAME, which is an up to date fork of MAME with a different video pipeline. Several other emulators are supported, and listed on the Groovy MiSTer page.
Groovy MAME offers a pre-built config file for Groovy MiSTer, so the steps are simple:
- Download and extract Groovy MAME
- Delete or rename the included mame.ini from the GroovyMAME directory
- Download mame_mister.ini, rename it to mame.ini, and put it where the original mame.ini was.
Finally, edit the new mame.ini file: search for mister_ip and change the IP in the new mame.ini to whatever fixed IP your MiSTer setup has.
And yes, this means your MiSTer must have a fixed IP, otherwise the two systems won’t connect. You can follow the official documentation for this.
The mame.ini file is how Groovy MAME knows to use the MiSTer system. If you want to use it for normal Groovy things, swap the two mame.ini files.
When launched the way it is now, the Groovy MAME window on the PC is invisible, but when active, still responds to button presses, ESC or ALT-F4 to close, etc. All video is sent to the MiSTer system. By default, audio is only heard on the PC, and controls on the MiSTer end are not enabled. For that, see
Step Three: The Rest
The setup is now complete, except for the tweaking. Launching the Groovy app from the MiSTer will show a black screen with a bouncing ball. This indicates that Groovy MiSTer is running and waiting for a connection from the PC.
Once it is running, you can use the usual MiSTer controls to bring up a menu, where you can do things like enable the PS2 keyboard, set your joysticks to digital, and turn on the sound. And you should do these things.
Once these steps were complete, I could play most games on my arcade cabinet with no hassles at all. Some things I haven’t yet worked out, like how to enable the coin input on the machine to ring in credits. The normal input configuration menu on the MiSTer only covers joystick inputs and buttons 1-8 for player one, the rest aren’t offered.
There are plenty of guides out there that will detail more of the configuration options available to you, but the default setup is, I think, the best for most purposes. I have an arcade cabinet with a 15kHz monitor connected to a MiSTer with an Irken Labs JAMMA Expander, and it worked without issue.
Some Caveats
Some things I noticed while testing this out:
The system is insanely sensitive to lag and throughput. I did all of this on WiFi, thinking it was using the wired connection. On my decade old laptop’s 2.4GHz wireless, bouncing through the floor to the router and back, it worked perfectly, but it was on the limit. There are times when it seems like Windows has some stuff going on and the video on the MiSTer stutters or collapses entirely and both Groovy MAME and Groovy MiSTer need to be restarted.
Once I switched to the wired LAN, it was near enough bulletproof.
When the lag gets you. Graphically complicated game and pulling up the menu is too much.
Groovy MiSTer must be launched first. There’s no reconnection logic in the setup, so if the MiSTer isn’t ready and waiting, Groovy MAME will launch, find no receiver, and not try again. Once Groovy MiSTer is running though you should be clear to stop and restart Groovy MAME on the PC as many times as you like.
Finally, one weird thing: Groovy MAME seems to rely on Groovy MiSTer for its timing. If Groovy MiSTer isn’t available when Groovy MAME is launched, the game will run at maximum overspeed. Sounds will be played back on the PC at 1200% (or whatever) and it’s a jarring thing when you’re troubleshooting.
This also happens when Groovy MAME isn’t the in-focus app, so if you alt-tab to another app on your PC, the video stream stops on the MiSTer end and the sounds will start screaming along at maximum speed until Groovy MAME is focused again, at which time the video and everything else will resume normally.
Conclusions?
This is a fantastic system that is fully functional and a boon to everyone with a CRT connected to a MiSTer. It is not a polished piece of software though, so there are caveats and little bumps and dropouts. It is a tragedy that Psakhis is no longer with us, but they’ve given us a tremendous arrow for our little gamer quiver, and I’m grateful.
I hope this guide was helpful. If you have suggestions or questions, drop a comment.
And if you got it working, check out the followup tweaks guide, making it even awesomer!
--NFG
[ Nov 4 2025 ]
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