Thanks for the bug report, I fixed it (bug was caused by me, too).
I changed it back to a "beeper". Does anyone know the freqency(pitch) of the beep? Actually a simple sound recording will do.

Hi hap, nice you're here!

I have two Mondials, I measured them with a guitar tuner.
Lower Serial one (older) : C6 - 1046.5 Hz
Newer: C7 - 2093 Hz

Danke =)

Now I'm even more curious! So it's a (small) hardware revision. Was the ROM updated too?
1046.5hz with a guitar tuner, if I had to guess, it's actually 1024hz, maybe divided from a 32768hz XTAL.

I don't think the rom was updated, but I suspect it's an active beeper with a fixed frequency, so they maybe just took a different one.

I can't (and won't) read out the roms, as they are soldered to the board.

Hier ein Bild mit dem Innenleben des (älteren) Mondial, mit dem schwarzen Beeper, vorne das ROM HGS 10 470 00.

Miniaturansicht angehängter Grafiken

 

Usually, a beeper doesn't oscillate by itself, it has an external circuit to automatically turn it high/low(like a 555 timer, or XTAL+divider), and then another (software controlled) line to enable/disable it.
*edit* top-left corner looks like a small XTAL, probably 32768Hz? for IRQ and beeper.

BTW that CPU is 1MHz, I guess it implies that the 1st Mondial is 1MHz, 2nd version is 2MHz.

hap, did you see this message?
https://www.schachcomputer.info/foru...postcount=2981

I saw you discussing it but I didn't see this post with the details. Thanks for reminding me, I'll update the driver.

I asked Sandro about it: he found the icons at offset 0xf77 of bw1_819n_u4.u4
Then he made a script to correctly map the pixels.

Angehängte Grafiken

 

hap, both Mondial solve a problem in the same time, I measured both near an AM-Radio, and the frequency is indeed near 1MHz.

As for the active buzzer, look here:
https://www.addicore.com/Active-Buzzer-5V-p/146.htm

Edit: The beep could also be generated with the 74LS14 and 74LS74 next to the silver inductor (or XTAL?) top left.