Is Fischer Time Implemented Correctly?

[RandyR]

I don't know why I didn't notice this before but I think our implementation of the starting time on the clock is wrong. If I select 15 10 in Fischer time, the clock has starting times of 0:15.10  0:15:10 and after the first move for White it changes to 0:15.20  0:15:10 and Black's time starts decreasing. I think there's an extra increment added as the starting times, which I believe should be 0:15.00  0:15.00.

Am I wrong or did we change something and just didn't notice it?

Randy

[Dirk]

Oh - you are absolutely right that shouldn’t be correct.

Von meinem iPad gesendet

Am 25.09.2025 um 16:37 schrieb RandyR <randy...@gmail.com>:

I don't know why I didn't notice this before but I think our implementation of the starting time on the clock is wrong. If I select 15 10 in Fischer time, the clock has starting times of 0:15.10  0:15:10 and after the first move for White it changes to 0:15.20  0:15:10 and Black's time starts decreasing. I think there's an extra increment added as the starting times, which I believe should be 0:15.00  0:15.00.

Am I wrong or did we change something and just didn't notice it?

Randy

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[RandyR]

It's in the timecontrol.py reset(self) function:

125        elif self.mode == TimeMode.FISCHER:
126            self.clock_time[chess.WHITE] = self.clock_time[chess.BLACK] = self.game_time * 60 + self.fisch_inc

I created a PR in your repo. Maybe Johan can adjust his fork as I don't know Git well enough to PR another fork (I think it's something like 'git remote add Johans_v4_repo https://github.com/JohanSjoblom/picochess' then checkout, etc).

Randy

[Johan Sjöblom]

This is so nicely served on a silver plate so I can adjust V4.

[DJ Dekker]

Hi Randy,

Nothing wrong here. PicoChess implements time increment in accordance with FIDE regulations. See for example this picture from the recent Grand Swiss 2025:

Greetings,

DJ

Op donderdag 25 september 2025 om 16:37:45 UTC+2 schreef RandyR:

[Randy Reade]

That's interesting. I'll have to look into it more. Could that just be how the clock looks before starting? I guess I could check the DGT 3000 part of my DGTPi. It doesn't make sense to me that the increment is already there, especially for Black.

Randy

[Dirk]

Oh I see - DJ is correct (I think they use the system: increment is added prior to the move and not after althoughjt that does not male any difference in the end I think)

FIDE handbook

increment

6.1

An amount of time (from 2 to 60 seconds) added from the start before each move for the player. This can be in either delay or cumulative mode.

[RandyR]

Yes. I learned something today. Thanks, DJ. Sorry for the panic, Dirk. It still seems odd to me that you get the increment before even making a move, but, as you can see, my chess knowledge is lacking. 🤭

[Johan Sjöblom]

So no changes needed in V4 then I guess or? I have not really played in competitions since the 80s and we used analogue clocks then :-) ... No Fischer increments back then.

And a question related to the nice picture above. If you would to use DGT PI to follow a competition game what mode would you set in Picochess? I would personally like the tutor to be running but be silent and not show anything except on the web interface. Then spectators would get real-time picotutor updates, but the players would only see the clock. But you can run lots of analysis programs later anyway so I guess the priority feature here is to keep track of time, and record all moves and produce a PGN file at the end. What mode would you use for that?

BR Johan

[RandyR]

No, no changes required.

Not really sure what you are asking in the second question. If 2 players are playing each other it would be Observe mode. If you are making moves for both sides of a game you are watching, probably Eval.Score mode. If you mean the players are using the DGT3000 portion of the DGTPi (so using the clock not in Mode 25) while the Pi is powered up, I'm not sure that is currently supported.

Randy