Mephisto London

aus Wiki, der freien Schachcomputer-Wissensdatenbank

Das Programmmodul London von Richard Lang war nie offiziell erhältlich. Es handelt sich bei diesem Programm um ein nachträgliches Update für die Mephisto Geräte Almeria, Lyon, Portorose, Vancouver, Genius 68030, Berlin 68000, Berlin Pro, welche ab 1996 auf das Programm London umgerüstet werden konnten. Das London-Programm ist vergleichbar mit dem PC-Programm Genius 3, welches 1994 den damaligen Weltmeister Garry Kasparov beim Intel World Chess Grand Prix in zwei 25 Minuten Partien mit 1,5 : 0,5 schlug!


Mephisto London 68000

Mephisto London 68020

Mephisto London 68030

Mephisto TM London

Extra Features list for customers Upgrading to London from Almeria, Portorose, Berlin and Berlin Pro.

From the MAIN MENU select OPTIONS.

In the OPTIONS listing, which commences with LANGUAGE ENGLISH, INVERT OFF, SOUND ON etc. the new FEATURES are:

  • 1. HASH
  • 2. STYLE


Your Mephisto London is among the very top chess computers which feature so-called hash tables. This term refers to a special, suitably organised part of the working memory that servers to store analysed positions together with their evaluations in a particularly economical and easily accessible fashion. If in the course of its analysis the London meets (by transposition of moves or from the previous ply of search) a position it has already analysed, it can retrieve the corresponding details in a flash without having to calculate the entire line afresh.

This is effective in all positions and particularly in endings as you can find out yourself by experimenting a little timing the search in a position with HASH ON und then HASH OFF. Disabling this part of the working memory to HASH OFF (by pressing ENT and the cursor key) will make the program slower and consequently weaker.


The London offers you a choice of three different playing styles. Use the LEFT and RIGHT cursor keys to select the desired setting from:


The recommended setting - and the one used when Genius 3 beat Garry Kasparov in the Intel Grand Prix - was ACTIVE. This is the style that gives the best overall results and the London will play actively and exec pressure on its opponent. SOLID stands for a more strategically oriented style of play that prefers security and avoids any unnecessary risks. Choosing RISKY will lead to more aggressive play and the program may be quicker to spot hidden combinations, but a quota of occasional mistakes due to over-enthusiasm may also arise.


In the default setting your London always calculates a maximum of 12 half moves selectively, beyond "Brute Force". By using the option SELECTIVE you can change the selective search depth choosing between 0, 2, 4, 6, 8, 10 and 12 half moves. When you reduce the number of selective plies, the London has more time available for further full width searching (i.e. calculating all possible variations) and it often happens that the London will play different moves compared with the default (12) setting. The default setting, 12 half moves, is the strongest selection for overall results.


The pawn structure database is at the core of the London's positional chess knowledge. It contains information on the optimal placing of pieces in relation to typical structures reached in the opening and middle game. Disabling this option will usually reduce the computer's playing strength actually be improved.


This option allows you to influence the program's evaluation of the position by changing the value it assigns to the pawns. You can change the setting in steps of 10% from 50% to 150%. For example a setting of 70% means that the loss of a pawn will be evaluated at only -0,70, so the computer will be more willing to sacrifice pawns for an attack or for positional compensation. Although the default setting of 100% does produce the best overall results other settings may be preferable in certain types of position. Quite a few players like to play their games with the pawn value at 90% for example.


The value options for each of the pieces works just like preceding one. In this case you can change the value assigned to each piece (knights, bishops, rooks and/or queens), and you can choose a value between 50% and 150%.