The Fritz/Rybka/etc. chess program’s shared user interface

I’ve recently received a few panicked phone calls and e-mails from new users of two or more of the Fritz family of playing programs (Fritz, Hiarcs, Rybka, Junior, and Shredder). “I just double-clicked on the Fritz12 icon and it launched Rybka4! How do I get my Fritz back???”

The fact of the matter is, your Fritz didn’t “go” anywhere. Both chessplaying engines share the same user interface – the “wrapper” containing the on-screen chessboard and all of the program’s various user commands.

I don’t often like to “recycle” articles I’ve already written (I generally prefer to start fresh when I need to cover a topic I’ve already written about), but the original article I wrote in 2002 which describes the Chessprogram shared GUI did a decent job of covering it. So what follows is partly based on my 2002 article, with a bunch of revised material near the end which updates the original article.

First, let’s look at some terminology we’ll need to know:

  • GUIGraphic User Interface. This is what you see on the screen when you fire up a computer program. In the case of chess programs, this includes the chessboard, informational panes, and the various pulldown menus that let you access the program’s features.
  • Engine — the “guts” of a chess program. The engine is the “brain” that does all of the chess calculation, either playing a game against you or analyzing a game that’s already been played.

In short, the engine is the part of the program that actually plays chess, while the GUI is the display on your screen — the interface that lets you interact with the chess engine itself.

Way back in the Dark Ages of chess sotware (pre-1997, give or take), the chess engine was basically “welded” into the GUI. You bought Chess Monster 5000 and it came with its own interface. You bought Killer Chess 2.0 and it, too, came with its own interface. But if you really, really loved the screen display, chessboard, and menus of Killer Chess and wanted to somehow run Chess Monster’s engine in it (because you really liked the way Chess Monster played), you had no way to do this; the two programs were completely separate and there was no way to run the Monster’s engine inside the Killer’s GUI. You were basically stuck with the combination of an engine and its interface — there was no way to divorce one from the other; in essence, the two were the same thing. To use an analogy (admittedly a bad one), it was like having to buy a new DVD player every time you wanted to watch a different movie, as though the movie itself was a permanent part of the machine and couldn’t be extracted.

There was a big downside to this “welding” of the chess engine and interface: if you wanted to play a different chess engine, you had to learn a whole new way of doing things in a different GUI — the menus were all different, the displays were all different, sometimes even the means of moving the pieces was different.

When Fritz5 was released in 1997, it gave you the option of using modular engines. You could run different chess engines written by different programmers in a single GUI, without having to learn a whole lot of new procedural stuff — the menus and other features remained the same (because you ran the engines in the same GUI — you just used a menu command to “unplug” one engine and load a different one, without having to exit the program and fire up a different interface). And you needed just one GUI on your hard drive. If you already had, say, Fritz5.32 installed and you later installed Hiarcs7.32, you could uninstall the Hiarcs GUI (while leaving the engine on your hard drive) — the Hiarcs GUI was exactly the same as the Fritz GUI, so having it on your hard drive was completely redundant because you could easily run the Hiarcs engine inside of the Fritz GUI.

Back in those days, there were only a relative handful of engines available to be run in the Fritz GUI. Now there are scores of them available online.

However, there’s now a new twist. All of ChessBase’s current playing programs use the same GUI. And I mean exactly the same – they’re all using literally the same files from the same folder on your hard drive for everything in the program except the chessplaying engine itself (as well as other changeable components, such as databases and opening books)..No matter which program’s desktop icon you double-click on, it always starts the same GUI. So it doesn’t matter whether you’re double-clicking on the Fritz12 icon or the Rybka4 icon or the Hiarcs13 icon, etc.; they’re all launching the same program.

So if you double-click on, say, the Rybka4 icon but the GUI launches with the Frirz12 engine loaded, how do you change engines back to Rybka4?

There are two ways to get to the dialogue which allows you to select an engine. One is to hit the F3 key on your keyboard. The other is to go to the “Engine” menu/tab and click the “Change main engine” button (highlighted in orange in the illustration below):


Fritz12 and Rybka4 chess playing computer software from

Click on the picture for a larger view

Either of these methods will bring up a dialogue which displays a scrolling list of all of your installed engines:

Fritz12 and Rybka4 chess playing computer software from

Just select the engine you want, set the hashtable size (and any other parameters), click “OK”, and you’re all set.

Thus the desktop icons and the “Play _______” displayed in the splash panel are purely cosmetic — they have absolutely no bearing on which engine is loaded and you’re currently playing/analyzing with. In other words, don’t fret — these aren’t the “old days” of “welded” engines and GUIs. Just think of changing a chess engine the same way you think of changing a disc in your DVD player (or changing an X-Box cartridge, etc.). The GUI is the DVD player or game hardware, while the engine is the movie DVD or game cartridge.

Have fun! – Steve Lopez

Chessplayers who have purchased their ChessBase brand chess computer software from USCFSales can receive free technical support and advice on their purchases straight from me; just shoot me an e-mail (, but please remember to include the USCFSales order number from your ChessBase software purchase. – Steve

Copyright 2002,2011, Steven A. Lopez. All rights reserved.


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Filed under chess, Chess DVD, Chess playing software, Chess software, Chess Tiger, ChessBase, Fritz, Hiarcs, Junior, Rybka, Shredder

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