PicoChess v3.4 'Trixie' Images [14 Dec 2025]

[RandyR]

Hi Everyone,

I have updated the v3.4 Trixie Desktop image to fix the missing support files required to run Dirk's Chess Transformer implementation of the chess-transformers project by sgrvinod. It is located in the Special & Historical Engines menu. I have also updated the Trixie OS system files.

With the release of Raspberry Pi Imager v2.0.0 you can no longer set up your wifi details within the Imager when selecting a custom image. You will therefore have to set it up after flashing. See the 'v3.4 Desktop Readme.txt' file for options. Another option is to use v1.9.6 of the Imager.

The Lite image is unchanged from the 31 Oct 2025 release.

Randy

The links remain the same:

64-bit v3.4 Trixie Lite (5.0 GB)

64-bit v3.4 Trixie Desktop (6.9 GB)

[Murat]

There is an imager version 2.0.2 at the github. I wonder if anything has changed regarding custom image.

[Randy Reade]

That’s actually the version I tested. It looks like Raspberry Pi dropped support for customizing custom images using the v2 imager. Possibly related to the move to cloud-init with their latest RPiOS images.

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[Håkan Löfgren]

I have recently upgraded from v3.3 Desktop 17 Jan 2025 to this v3.4 release. I works quite nicely, but I have stumbled on a problem: As I own a RISC2500 chess computer, I have also used it as a retro engine with rom 2500.zip on v3.3 without any problems. 

When I try to start it on v3.4, picochess now hangs during engine setup. The 2 files in the rom are dated 1996-12-24; I am not aware of any newer rom. 

Testing with mess -verifyroms reports bad rom; risc2500.svg (221222 bytes) - NOT FOUND

Running the engine from the command prompt reports fatal error; risc2500.svg NOT FOUND (tried in risc2500)

During unzip it also reports risc2500.zip has no ZIP64 ECD locator, whatever that means?

Any help solving this problem would be much appreciated!

/Håkan

[Randy Reade]

Håkan,

I can't check any PicoChess stuff at the moment but you likely have the wrong rom. You'll need one containing that SVG file. The ROM set that you use has to match the version of MAME in PicoChess. You can disregard the ZIP64 ECD locator error.

Randy

[Håkan Löfgren]

Randy,

I have made some progress. I have found 2 fairly new roms containing the SVG file:

v1.04 rom: risc2500 with files st17_a22_u_7.u7 and risc2500.svg

v1.03 rom: risc2500a with files st17_a15.u7 and risc2500.svg

Both roms pass the verifyroms test. 

v1.04 does not work at all. Testing from command prompt reports that neither of the two files can be found. 

v1.03 works better. When I start the engine the artwork appears and can be switched back and forth! However when I make the first move e4, it shows in the artwork but the engine reply never happens. If I for instance choose 5min/game the clock ticks down and when it reaches zero picochess announces LOST ON TIME, WHITE WINS. Quite easy win:-)

Seems that my move is never received by the engine?

/Håkan

[Randy Reade]

Håkan,

You could try moving the risc2500.svg file inside your original rom zip file that worked in v3.3, but I suspect there might be some changes needed to the applicable LUA file inside the mame_emulation/plugins/chessengine/interfaces folder. Another option is to use the mame_emulation folder from v3.3, replacing the one in v3.4 (essentially going back to an earlier MAME version).

I’ll have a look when I’m able to but that might be a while.

Randy

[Håkan Löfgren]

Randy,

First of all; Thanks for your tireless help!

I included the SVG file in my old risc2500.zip and started the engine with level 5min/Game. The result was like the test with risc2500a.zip; artwork showed up, I entered e4 move, it was reflected in the artwork, after 5min I won on time. 

I guess some lua handwaving will be needed to solve the problem…..

/Håkan

[Aldo Bleeker]

I've tried Mess engines recently, and I've noticed the same thing with the Mephisto Berlin Professional 68020. Mess itself is working great, when I move the pieces on the Mess board that opens, the engine responds and lights the LEDs to indicate its move. The same when I start Mess directly. But when picochess starts the engine and I move a piece on the Chessnut Go, say e2-e4, the piece is moved on the picochess board and the move e4 is displayed, but the engine doesn't show the move, and picochess' menu doesn't respond anymore until I restart the picochess service. When the engine is started, picochess says 'Engine setup', but it doesn't say 'Engine OK'. However, I'm not using the 3.4 Trixie image, this is a Debian Trixie x86_64 PC with picochess 4.2.0. I'm using the MessChess roms.

[Randy Reade]

What happens when you turn retro artwork off? Does it still hang? You can also try running it from the terminal and entering UCI commands into the command line:

cd /opt/picochess/engines/mame_emulation

DISPLAY=:0 SDL_VIDEODRIVER=dummy ./mess -video none -plugin chessengine berlinp

Then:

uci

isready

position startpos moves e2e4

go movetime 5000

Randy

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[Aldo Bleeker]

Picochess still hangs when the artwork is switched off.

Running the commands in the terminal works. Starting mess directly works as well.

I've switched to the mame engine, but the name in picochess isn't changed. The move is displayed by picochess, but it looks like it's waiting for the engine, and the engine seems to be waiting for a move. The menu isn't responding anymore, but picochess isn't actually hanging, because it starts a new game when I take the move back.

I've attached a debug log. This is trying to run mame engine amsterd from the Mephisto Amsterdam that's included with the engine package.

Aldo

[Randy Reade]

This line is curious:

2026-02-01 14:27:53.053 WARNING engine - error_line_received: <UciProtocol (pid=13574)>: stderr >> Authorization required, but no authorization protocol specified

Unfortunately I can't check myself. I assume the folder permissions are set to your username ('sudo chown -R <username>:<username> /opt/picochess'). But, perhaps not related.

Randy

[Aldo Bleeker]

I like the permissions idea, I've copied the roms from MessChess on a Windows partition. I've chowned /opt/picochess like you've suggested, but unfortunately that didn't help. The authorization is still required and i have no idea what authorization protocol to use, or how to specify one.

Aldo

[Aldo Bleeker]

I've compiled the current mame 0.285 for x86_64, renamed it to mess and placed it in picochess. It's a full version, and it's about 5 times bigger than the chess version of mess, but Mephisto Berlin Pro and other roms are working. However, some roms still aren't, for instance the RISC 2500. This probably is an issue with the original machine or the rom, there's a warning before it starts saying the timing isn't correct.

Aldo

[Randy Reade]

Yes, the version I use just has the chess machines, and I also incorporate some edits (in ui.cpp and mainmenu.cpp) to block the nag screens (otherwise you would get popups for many retro engines). I should be able to get back to PicoChess soon and will look at all the issues that have been mentioned.

Randy

[Håkan Löfgren]

Montreux is basically the same machine as risc2500 and the only difference between its new and old rom is the addition of the SVG-file; seems like a good candidate for further testing. 

Currently when testing, it shows the same result as risc2500, i.e. shows move in artwork and hangs until loosing on time. 

/Håkan

[Randy Reade]

Thanks for the info, Håkan.

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[RandyR]

It appears the issues with risc2500 and montreaux are rom related. './mess -verifyroms' will show which roms are incompatible with the mess (MAME) version that PicoChess is using. You need to use roms from that release. I won't say where to get roms but a hint would be the MessNew folder. 😉

[RandyR]

Aldo,

It sounds like your Chessnut Go is now working. I tested using my Millennium board via Chesslink and Mephisto Berlin Pro in PicoChess v4.1.9 {on x86_64) and moves were recognized in PicoChess. As I mentioned in my previous post, it looks like a rom issue in your case as well.

Randy

[RandyR]

Ah, it appears the x86_64 engines archive I shared did not have the no-nag edits in the MAME compilation so if artwork is enabled the popup will show when running Mephisto Berlin Pro and PicoChess will hang. At least that's what I'm seeing in v3.4 under x86_64 - maybe there's code that works around that in v4 and that's why it worked there for me. I'll recompile v0.279 and see if the no-nag edits fix the lockup. I'll update to the latest MAME version in the future when I have time to analyze the retro-engine code changes.

Randy

[Aldo Bleeker]

That's looking promising!

But I'm now wondering if the issue with the Saitek RISC 2500/Mephisto Montreux is caused by the rom, because the same rom is working in MessChess with Arena. When I move a piece on the Chessnut Go, this piece is then moved on the MessChess board, and the engine's move is displayed correctly on the eboard by lighting up the LEDs. It's a different system of course, it's using Graham's driver, but it looks like the rom itself is functioning correctly.

Aldo

[Håkan Löfgren]

Randy,

I think I have the recent roms but to be absolutely certain, I have reinstalled it from the beginning:

I used the roms from MessNew:

montreux contains risc2500.svg 2025-06-24 and rt17b_103_u_7.u7 1996-12-24

risc2500 contains risc2500.svg 2025-06-24 and st17_a22_u_7.u7 1996-12-24

I checked with mess -verifyroms that the roms are good and checked with Arcade DB that the files in the roms are correct for mame 0.278->0.283. 

An observation on the artwork. The white band in the lcd screen fast blinks  at start up and then stays as in the picture. 

/Håkan

[RandyR]

Yes, there does seem to still be an issue with risc2500, at least in v3.4 on x86_64. I need to switch back to v4. I was sure it was working there but maybe I didn't enable artwork when testing.

[RandyR]

Same in v4. I guess my test wasn't very good. It looks like a LUA issue. I'll see if it's something obvious with a simple fix...

[RandyR]

Here's the corrected LUA file that will fix both risc2500 and montreaux (which calls the risc2500.lua script). Just place it in the /opt/picochess/engines/mame_emulation/plugins/chessengine/interfaces folder, replacing the current risc2500.lua file.

Enjoy!

Randy

[RandyR]

I don't own that machine so not sure how it looks in real life (is the top of the LCD highlighted?) but if you want to remove that white background, just edit the /opt/picochess/engines/mame_emulation/artwork/risc2500/risc2500.lay file and change the screen blend attribute from 'alpha' to 'multiply' in the lcd panel section (around line 343):

<screen index="0" blend="multiply" ><bounds x="0" y="0.35" width="30" height="3.6986" /></screen>

NOTE: If anyone wants to change the artwork, press the TAB key on an attached keyboard, select 'Video Options' (use up/down arrow keys and ENTER), then 'Screen #0' and select the artwork you want. Press TAB key to exit menu. Internal Layout is what comes with MAME. Press TAB key to exit menu. These changes are saved into the cfg folder in mame_emulation.

Randy

On Sunday, February 8, 2026 at 1:22:46 PM UTC-6 hawk...@gmail.com wrote:

[Håkan Löfgren]

It’s getting late here in Sweden, but I just had to do a quick test with RISC2500. Thanks a lot for your quick fix, it really helped!

The picture shows the short game. The engine stopped responding after my b3 move. Perhaps an original bug in the rom, but I will test more tomorrow and also have look at the artwork. I might try to fire up my old machine to see what the white strip actually contains. 

/Håkan

[Aldo Bleeker]

https://www.schach-computer.info/wiki/index.php/Saitek_RISC_2500 has photos. My picochess here shows the first line in a white band.

RAM is empty

01 00:00 00:00

()

That first line looks distorted as well. I think the white band isn't supposed to be there and the first line shouldn't be distorted.

Aldo

[Randy Reade]

That's the custom artwork from Luis. I don't think there is any update.

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[Håkan Löfgren]

I have now done some further testing of both engines. They mostly work fine, but sometimes they stop responding. For example: I replayed the RISC2500 game that stopped responding in move 10 and now it continued to the end of the game. In another game with Montreux, it stopped responding when it was about to promote a pawn to win the game in few more moves. 

However no suprises, these things also happened in v3.3 of picochess. 

Concerning artwork: The white strip is the message area for the engine. It displays all sort of things like feedback when moving around in the menu, open name, pv line, etc, etc. 

As Randy points out, it is easy to change the white background to grey to make it less noticeable. However, I can’t figure out what message the emulation tries to display.

/Håkan

[Randy Reade]

There might be issues with the 'show info' code. Dirk and I discovered that it can sometimes cause problems. Here's a version of the risc2500 plugin that has the info code stripped out. Let me know if it helps.

[Håkan Löfgren]

Randy,

Looking in the lua file you just posted, I can see no difference versus the previous lua. All info stuff at the end of the file are still there?

/Håkan

[Håkan Löfgren]

Randy,

Disregard my previous message; I now see your change! I will test and report back

/Håkan

[RandyR]

It's all commented out (--[[ and --]]).

[Håkan Löfgren]

Randy,

I have now tested your latest risc2500.lua with 10 games. Works well, no unexpected hangs, but both engines have a persistent issue. They are unable to promote a pawn. They march with the the pawn with the intent to promote; when the pawn reach rank 2 the next move should be a promotion. Instead they stop responding and hangs. 

Perhaps something wrong in their common lua file; I have seen some promotion stuff there:-)

/Håkan

[Randy Reade]

Thanks for the testing, Håkan.

I'm not too surprised about the promotion not working as the LUA files have not been updated consistently. I'll have a look when I get a chance and see if I can figure it out. But it's not always simple to fix (for me).

Randy

[Randy Reade]

Håkan,

Can you test the attached file for promotions?

[Håkan Löfgren]

Randy,

Will do and report back. 

For some reason I could not download the file, but I could copy the function get_promotion to my LUA file. 

As far as I can see only this function has changed.

/Håkan

[Randy Reade]

Yes, that was all that changed. I'll check the attachment again.

Randy

On Sat, Feb 14, 2026, 5:11 p.m. Håkan Löfgren <hawk...@gmail.com> wrote:

Randy,

Will do and report back. 

For some reason I could not download the file, but I could copy the function get_promotion to my LUA file. 

As far as I can see only this function has changed.

/Håkan

lördag 14 februari 2026 kl. 22:20:59 UTC+1 skrev RandyR:

Håkan,

Can you test the attached file for promotions?

On Fri, Feb 13, 2026 at 1:48 PM Håkan Löfgren <hawk...@gmail.com> wrote:

Randy,

I have now tested your latest risc2500.lua with 10 games. Works well, no unexpected hangs, but both engines have a persistent issue. They are unable to promote a pawn. They march with the the pawn with the intent to promote; when the pawn reach rank 2 the next move should be a promotion. Instead they stop responding and hangs. 

Perhaps something wrong in their common lua file; I have seen some promotion stuff there:-)

/Håkan

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[Randy Reade]

Seems to download for me. 😊

On Sat, Feb 14, 2026, 5:11 p.m. Håkan Löfgren <hawk...@gmail.com> wrote:

Randy,

[Håkan Löfgren]

Thanks Randy,

The replacement of function get_promotion in the risc.lua file solved the promotion error.
These engines now work as they should without any (known) issues!

/Håkan

[Randy Reade]

Good to hear, Håkan. 👍