My 'strong club player, class A level' chess computers

Mephisto Rebell 5.0

Year: 1986
Programmer: Ed Schröder
CPU: 65C02 @4.9Mhz
ROM: 32Kb
Elo level: 1802 (1744 FIDE)
CMhz: 4.9
Rperf: 99%
KT: 1506
Square size: 1.18"

This module is the missing element between the Mephisto MMII and the MMIV. It should have been named MMIII, but the program performed so remarquably during the 1986 world computer chess championship (WCCC), the brand chose to leverage its fame. Rebel finished this WCCC at fifth rank (and 1st microcomputer) after having been in a position to win it! Facts are it won its games against a cluster of 20 parallel computing 32bits SUN, a Cray XMP, and an Amdahl 470 whose program (Bobby) did win its own game against the title owner (and future final winner) Cray Blitz. And this using an Apple IIe, however featuring a bitslice accelerator card (most probably a Schaetzle & Bsteh DC65, launched in 1984 for the Apple II). Such a card is able to accelerate the original 1Mhz 6502 up to 11 or even 12.5Mhz; but it has been set to half-speed in order to keep control on the clock, resulting in 5.5 to 7Mhz depending on the source (Jan Louwman or Eric Hallsworth). So the later sold module provides a performance level close to the one of the WCCC hardware. It is the outcome of the very first joint work between Ed Schröder and Hegener & Glaser, and many other products will follow, stronger and stronger (MMIV and MMV, Polgar, Milano, Risc...) until 1994; then the author will set up in business on his own with the PC-Rebel series, starting from Rebel 6. As I much appreciated the PC-Rebels, I was keen on inserting an Ed Schröder's program in my collection. And this Rebell 5.0 is a true milestone... I bought it €118, with the Modular Board, the chessmen, the  mains adapter and the user's manual, on German eBay.


The skills profile of the Rebell 5 displays much contrast, revealing so a young program still lacking some development: very relevant after exiting the openings book, it definitely fails the endgame standard positions exam. We can see the programmer took particular care over injecting a fair amount of chess knowledge to get the program to develop its position and play good positional moves (strategy). So, the Rebell 5 did study the chess manual, but not to the last chapter... The middlegame playing strength is rather average, the defensive skills as well, while attacking and sacrificing abilities are weak (but this is not unusual with any program from the same era), and the program is more comfortable with recognizing threats, with leveraging tactical patterns, and with counterattacking - there again, rather usual properties, driving some passivity, awaiting opportunities to appear. The most surprising result, with regards to the rather fast processor back in time, is the poor calculations performance. Nevertheless, the Rebell 5 is a strong player, thus reinforcing the feeling the programmer did inject much chess knowledge (endgame kept apart), resulting in a rather sophisticated evaluation function, so a bit slow one.

Novag Super Nova

Year: 1990
Programmer: Dave Kittinger
CPU: 6301Y @16/4Mhz
ROM: 32Kb
Elo level: 1813 (1752 FIDE)
CMhz: 3.36
Rperf: 101%
KT: 1610
Square size: 1"

Within the Novag series I kept an interested eye on the Supremo, as:
- it offers a 32Kb program, which is the entry point for the best Novag programs;
- it deserved excellent comments in Jeux & Stratégies #54, decembre 1988 edition:  "An appropriate analysis of the program reveals it is very close to the one of the Super Constellation, with less openings: nevertheless 1,500 moves, and less endgame knowledge. The Supremo is one of the best value for money, not only within Novag series, but also over the whole market offer."
- it features a playing style reknown for being of interest, even if actually not so close to the Super Constellation's one.
In respect to this good fame, to my opinion the Supremo got a bit overpriced today, and uneasy to find. The best approach seemed to search for the Super Nova, of same form factor as the Beluga, but hosting the 32K Supremo program, powered by a twice as fast clock. I purchased a first one for €50 on "le bon coin", including the chessmen, the user's manual, and an original Novag mains adapter - only the original packaging was lacking. But the row of keys in front of the display failed to react, thus disabling some most useful settings such as the choice of the playing level. Otherwise it worked like a charm, too bad... I unscrewed the box and carefully checked the electronic without being able to resore the keyboard to life, so I purchased another one, fully working, for €60. This later one had no adapter nor user's manual, but the packaging was offered. At the end of the story, I had a fully working and complete set, and additional chessmen I could reallocate to the Beluga. The design of the Super Nova is close to the Beluga one, with darker colors where black prevails, underlined whith light touchs of blue/green. Unlike the Beluga, the center of the board is rigid enough, pleasant to use.


Khmelnitsky test: a mighty counterattacker! After a robust opening, its level of play is rather common on many domains: middle game, endgame, attack and defense (even including sacrifice) are much balanced but a bit low (in the 1500 Elo zone). Calculations ability is very limited, expectedly on par with the Beluga featuring the very same processor (6301Y, a rather weak microcontroller despite the unusually fast clocking used). So, the additional 136 Elo points featured by the Super Nova (1610, compared to 1474 for the 16K Beluga) fully rely on the 32K software. And to reach better calculations skills, you need to jump to the fast H8 (13.3Mhz) powering the Emerald Classic!

Yeno 532 XL

Year: 1989
Programmer: Ulf Rathsman
CPU: 65C02 @4Mhz
ROM: 32Kb
Elo level: 1831 (1765 FIDE)
CMhz: 4
Rperf: 101%
KT: 1685
Square size: 0.9"

The second Yeno chess computer (1st one was the 301XL), and the strongest one from this brand. With assets such as its 32K, its 4Mhz 6502, and its program close to the Mephisto MMII one (based on Plymate), it is a strong player, uneasy to find on second hand market. I spent a long search time before finding this one, bought for €80. The small diods are modest, one per square, level with the playing surface like the modular board ones. They are sometimes hidden by the pieces, which are a bit large compared to square size, and too light and not magnetic enough for a good holding on the board. Fortunately the moves are displayed in two small LCD windows, offering in sequence various information. Unlike the 320 XT, the control panel is pleasant to use, the keys are push sensitive with as little pressure as the squares require. The one I own failed after circa one hour to one hour and a half playing, some contiguous squares ceased to respond to push. An area on the left of the chessboard was overheated. After turning the computer off and waiting a while in order to let it cool, the square sensors were restored. I performed a careful dismantling/reassembling, with a meticulous positioning of ribbon cables connecting the mother board to input/output devices (push sensitive chessboard, LCD displays); I reinforced a heatproofing Bristol board with a second layer of thick paper, and drilled holes under the hot area, in the black plastic bottom cover. Not a quite purist way to do as a collector of chess computers, but invisible while playing, and my 532 XL never failed again. Maybe the careful reassembling would have done the trick, however the hot area completely disappeared. The most important thing is to play again, isn't it?



Overall, a usual profile shared with many other chess computers from the same or so period of time (the program can be considered dating from 1985, birth year of the Mephisto MMII); featuring a strong game in the beginning phase, lowering slightly in the middlegame, especially due to a lack of strategic relevance, then dropping significantly in the endgame. Its strength is mostly based on tactics, with counterattack in clear preference to attack. Finally, the calculations ability is disappointing considering the 4Mhz 6502; this reveals an essentially brute force approach, unsuitable to selectively deep dive into variations. The global score is nevertheless quite satisfactory, the Emerald Classic is the only one achieving a higher score in this class!

Excalibur Ivan the Terrible

Year: 1996
Programmer: Ron Nelson
CPU: H8 @12Mhz
ROM: 48Kb
Elo level: 1832 (1767 FIDE)
CMhz: 7.8
Rperf: 98%
KT: 1409
Square size: 1"

Ron Nelson has left his mark on the chess computing world with his skills as an electronician engineer, but he was as well a pioneer programmer, author of the famous Chess Challenger series before the Spracklen started working for Fidelity. I got lately interested with the Excalibur brand story and discovered recently Ron Nelson's production in this context. Not only he designed the devices, but also he authored the program, including the attack bitmap concept and using the map generation process explained by Ken Thomson, the famous author of Belle. So I started my quest for one of his program running on H8, preferable to later ones for which the H8 was no more available. Thus the author has translated his program for another microcontroller, 6502 like, but with less RAM, this led him to remove the attack bitmap tables; at the same time he disabled the permanent brain to mitigate any bug risk and enhance the batteries life (Ivan II the Conqueror, Alexandra the Great, both from 2003). The devices powered by a H8 are the Mirage (featuring robotic move of  the pieces), Ivan presented here, Grandmaster (a de luxe one with a high quotation), and Igor. Ivan and Igor seem to be very close, and feature voice and entertaining sounds, not necessarily enjoyed features by serious chess players. Indeed it increases the toy aspect of this chess computer, despite its strength, yet these features can easily be disabled. Ivan voice messages are chosen according to the game status, with a sense of humour. As an example, using the 'hint' key can result in hearing: 'a hint? You do not need a hint!' if Ivan evaluates itself in a loosing situation; or 'you want a hint? Resign!' if it has a neat advantage. It nevertheless generously suggests a move assuming you hit the key a second time. Cherry on the cake, the voice compression used has been designed by Ron Nelson as well! A nice buy from UK, for €51.



I was keen on measuring Ivan's behavior while performing the Khmelnitsky test: Excalibur devices were distributed late in the market life (starting from 1993), and the market had started to shrink, facing PC programs competition. They mostly aimed at general public market and could not benefit from the reputation built on comparative testing, that was very popular since the early chess computers appeared. In addition, let us consider an unusual combination including a programmer initially known for his primitive programs fitting occasional players' level, but now leveraging re-introduced attack bitmap technology (old, but having stood the test of time), and a fast processor; the result being a definitely strong chess computer. To be honnest, Ivan didn't shine in this test: it often succeeded in evaluating correctly the diagrams (identifying who is best), but it too often failed in spotting the best move (scoring five points) while choosing a decent but suboptimal one (scoring only one point). This lack of accuracy augmented by too many fails with endgame positions resulted in a loss of hundred points or so, with regards to other devices within the same category. The skills profile is typical for early chess computers: ability to spot threats (thanks to the attack bitmaps), tactical strength, strong defensive and counterattacking skills; with a spike of strength at middlegame, clearly lowering at endgame. The already mentioned lack of accuracy often prevents it from finding the most decisive attacking moves. As a conclusion, Ivan fits its marketing target: a strong player (you would better try to resist to, until endgame is reached), but no analysis tool... Nevertheless, Ivan does not deserve a too negative perception: I strongly advise you to use the comparison tool, and overlap its profile with the Saitek Turbo King II D+ one. This Kaplan program deserves an excellent fame, and you can check by yourself Ivan is definitely on par regarding most of the domains! To conclude with some fun, I discovered while performing the test some retorts from Ivan, I had never heard during standard games: should you handover your turn-to-move to him, with a loosing position: "no way, I don't want your mess" (you then need to presse "move" again); and if exiting setup with a diagram without queens, he sometimes would moan: "what is this? Where is my queen?"

Tiger Grenadier

Year: 1998
Programmer: Chrilly Donninger
CPU: SH7034 @20Mhz
ROM: 32Kb
Elo Level: 1844 (1776 FIDE)
CMhz: 23
Rperf: 94%
KT: 1541
Square size: 0.94"

I bought this Grenadier (€60 on Le Bon Coin) from a collector, who warned me: the playing style is somewhat disconcerting, but interesting. Actually I already had read such comments, and it confirmed part of my motivation to add it to my collection. The rest of my motivation: the author, the brand, and the processor (a fast and powerful Super-H Risc) at that time not present in my collection. This device is the single one authored by C. Donninger (it also exists in  few numbers branded Millennium and named Genesis, and  the Sakkara Vega uses the same program in a different housing). I am not fond of Nimzo, to my opinion its playing style isn't up to much; but I knew I would find something different with the Grenadier. It has a talent for playing unusual openings, then carry on playing surprising moves and displaying optimistic scores (proved false by any chess engine), later suddenly change his tune, admitting a negative score, and from then on, resume a more serious play and slowly get back on its feet, to score a draw that came out of nowhere, sometimes even win... I would qualify its playing style as speculative.
Another peculiarity of the program powering the Grenadier is to enable some tuning regarding its playing style, thru changes applied to evaluation criterias. My approach in this area is definitely to keep its original playing style, so not throw into confusion any parameter; but tune using marginal updates. The trigger for such tuning is blunders the program may play. I then look for which parameter can significantly modify the chosen move and avoid the blunder, and what value as close a possible to the default value can achieve this result. Next step is validation... I do it using three methods:
  - play a few games "under survey" of a strong chess engine (most often HIARCS 14). If the engine reveals a quite bad move played by the Grenadier, I take back the move, and resume computing using Grenadier's default value for the considered parameter. Should the standard one play roughly as bad, the new setting would be declared not guilty.
  - Eight games gauntlet against the very same opponents the standard Grenadier faced once ago, scoring 4 points out of 8 (a balanced score). A better performance using the new setting is obviously welcome.
  - Playing skill evaluation based on five classical games, playing white and black moves, providing a score per each move. The overall rating is measured using "Elo points". The absolute value does not matter, the point is to check whether the new setting do provide any significant gain (if not, better jettison it, at the benefit of the playing style) ; and check as well whether this gain is balanced enough across the five games (to avoid introducing any weakness in some situations). This test designed by Spacious_Mind is available for download here.
Currently, my best setting alters both two parameters: "Pawn" (pawns structure) raised from 0% to 2%, and "Shield" (king safety) raised from 20% to 25%. Excerpt from my 'Spacious_Mind' test results (best scores per game are underlined using yellow color):

Update: being 10 years old, the Spacious_Mind test deserved a refresh to take advantage from the improvement of top software, so I redesigned it based on Stockfish 16 and Dragon 3.3 (by Komodo). The process is described and the reloaded test is available for download here. Of course I assessed again the above settings using this updated test:

The best setting is unchanged.




The known lack of development suffered by this program translates here into a rather irregular profile. It is also atypic (as expected), showing attacking skills plainly superior to defense ones, unlike most programs. I pointed out its behavior trend to select rare openings; the graph displays an aggravating factor: it does not master the opening transition to early middle game, once out of book. So, it is no surprise it often faces tricky situations during this very phase. On another hand, the middle game is its favorite domain, leveraging strong support from tactics and, which is unusual for a chess computer, a consistent strategy knowledge. It is exactly from this starting point it does resume the serious play I did mention above... and, should the occasion arise, it launches a counterattack to reverse the previously threatened situation. More commonly, endgame is weak and it does not know much about standard engame positions. Lastly, the calculations ability is deceptive with regards to the powerful processor, thus explaining further its low Rperf, worthy of a full category under this one! 

Saitek Turbo King II

Year: 1990
Programmer: Julio Kaplan
CPU: 65C02 @5Mhz
ROM: 64Kb
Elo level: 1882 (1804 FIDE)
CMhz: 5
Rperf: 103%
KT: 1506
Square size: 0.98"

To get a strong Kaplan program, my choice balanced between the Tandy Chess Champion 2150 and the Turbo King, and I finally, reasonably, chose the Tandy: better adapted to my budget and to my playing level. But the seductive power of the Turbo King did not die down completely... So, when I happened to spot this nice one offered on French Le Bon Coin for €30, I went wild over it... Usually, one would have to offer slightly more than €100 to buy this device! The EGR (End Game ROM) was not present, but tests I performed have revealed the software is the 'D+' version; quite different and performing better than the 'B' one used into the Tandy. In addition, Julio Kaplan's program being chess knowledge oriented, needs computing time to provide full extend of its strength; it improves a lot running at 5Mhz instead of 3 as it does on the Tandy. Showing 150+ 'Elo' points as an order of magnitude, the Turbo King is far from being a duplicate in my collection!



The Turbo King II transitions perfectly from the end of the openings book to a solid middle game, leveraging tactical skills (recognize threats, calculate, defend and counterattack): chess computers often provide evidences for such properties. Considering the program is well known for being chess-knowledge oriented, and so being rather slow (310 nodes per second as an order of magnitude), its lack of knowledge for standard endgame positions and its relative weakness in positional skills (strategy) are disappointing. Compared to other versions of Kaplan's chess computers, while neutralizing their various processors power impact, it runs roughly half-way speed between the "B" version of the Tandy 2150, and the much lightened version of the Saitek Blitz. So, this D+ version has probably been lightened as far as chess knowledge is concerned, in order to speed up its evaluation calculation, and so be able to analyze deeper. The result is far from being uninteresting; its profile is very similar (of course weaker) to the one of the Mephisto Berlin, with which it shares a certain amount of passivity (attack). Considering the domination of Lang's programs, leading towards a similar pattern makes sense. In a nutshell, a mini-Berlin/Vancouver, except their endgame strength!

Novag Constellation Expert

Year: 1985
Programmer: Dave Kittinger
CPU: 65C02 @5Mhz
ROM: 64Kb
Elo level: 1900 (1817 FIDE)
CMhz: 5
Rperf: 104%
KT: 1685
Square size: 1.57"

That's a nice chess computer! (purchased €350 on eBay, complete and thoroughly working).
It is the first one Novag built using wood, it is impressive with its size and quality of manufacture. It is the direct heir of the 1984 Super Constellation, to which it owes its "Expert" title. Sidelines on history: Novag entered the Super Constellation into the official ranking process proposed by the newly-established Computer Rating Agency (a spin-off of the U.S.C.F., the US chess federation); this Expert title will be awarded after 40 games played under tournament rules, facing ranked players, and a 55% score against the average 1982 Elo opposition (resulting in a 2018 Elo points performance). As the C.R.A. official ranking process was billed $2000 (a large sum by then, thus few brands will use it), Novag will try to get some return on investment, re-using the Super Constellation program in this sumptuous and slightly enhanced variant. Despite some Experts are clocked with 4Mhz as the Super Constellation is, it has rapidly been made available with 5Mhz, or even 6Mhz. The ROM size increased from 56Kb to 64Kb, the ability to store new openings was removed, but the program could reach deeper calculation, offered more settings for the level of play, and improved its positional play. But the most important point is it inherited to the full the PSH algorithms that made its predecessor reputation: these are the Pre-Scan-Heuristics. The idea is to analyze the position before getting deep into the tree of moves, in order to identify potential attacking patterns, desirable spots for pieces, to later assign the relevant bonus to positions that will be evaluated the classical way, exploring the tree of moves. The advantage of this PSH approach is to avoid re-computing these key elements of positional analysis with each node within the tree, the calculation time would be dissuasive; on the other hand the deeper the program searches, the farther the resulting position goes from the initial one, and so the PSH analysis consistency decreases accordingly. Beyond a certain depth of analysis, it probably goes counter-productive; so the raising of computer performance will doom it to be abandonned. In its historical context, it grants the program excellent attacking skills, including sacrifices, and particularly in speed play where it can play, without requiring any tactical validation, moves a human player would consider intuitive. By the way, the program will be nicknamed "Blitz Monster" after the 1984 Hong Kong blitz tournament, where the Super Constellation scored 19 out of 28 points, of which 5 facing IMs (International masters, ranked in the range 2355 to 2474 Elo!). But facing other chess computers, due to some "intuitive" initiative, this program can take a punishment from the opponent's tactical skills, so Novag and Kittinger later resigned using it (or made it way more unobtrusive) for the successors (Super Expert/Super Forte). The experimental program suffered a bitter defeat during the 1985 WMCCC in Amsterdam (world microcomputer chess championship): despite three entries (named Monster-C, Monster-X and Monster-Y) it achieved 5th, 13th and 16th rank out of 16 participants. Despite Novag having widely claimed they don't care about other chess computers competition and they consider most an interesting game for human opponents, the hit is painful, and the spectacular way of playing of PSH algorithm will barely be anymore noticeable with the successors of the Super Constellation and Constellation Expert. In this sense, the Constellation Expert is representing the heigth of the PSH! Eric Hallsworth describes it in his periodical publication Selective Search #10 october/november 1986: "Inventive. I am sure most folk know that the Expert is programmed to seek complications, take risks, create unpleasant alternatives for the human mind to battle with etc." From my more personal standpoint, despite not being strong enough to resist the Expert, I often feel I can understand its moves; even if I would not have found them myself, I see the point and understand the reason. Sometimes, the PSH algorithms enable what looks like a short-term or mid-term plan the program chooses without complete tactical validation; at last a very human-like approach, with balanced chances for success or failure - again granting a very human-like play. The lack of any display prevents performing the Khmelnitsky test, on another hand I feel the chessboard nicer without, if I compare it to the successors Super Expert and Diablo. The chess pieces also contribute to the overall beauty of this chess computer, some pictures are available here in this page.


This is inconsistent with the above assessment about the Khmelnitsky test! Actually, lacking any display, the Expert can alternatively feed a printer. I do not own one, but I requested support from other collectors, expecting a sample of scores that would result from simple positions; and I would like to thank again Olivier for his useful help. The trick I then leveraged was playing these positions using Franz's emulator (MESS based) in debug mode, meticulously looking for the score values in RAM. It has been a busy bee work (a dozen hours!) as the score printed as decimal is encoded as hexadecimal in the RAM, and the encoding way was unknown to me. I finally spotted the location of the data and set a translation formula in a worksheet, providing the exact result reflecting the initially printed control sample. Et voilà!
The skills profile is somewhat unusual, I didn't expect less from a program featuring PSH algorithms. The most outstanding measure is strategy, even though this domain is usually weak for chess computers. Achieving 1939 test points, the Expert handles this domain better than most of the devices ranked in the stronger category; actually only the King Performance achieved a higher score. Even a human player globally on par (1685 Elo) is clearly dominated in this area, this is much unusual. This peculiarity is shared with another device from the same author, the more humble Beluga. Would it be a footprint of some PSH algorithms being present in the Beluga? Another uncommon aspect of the Expert is to be nearly as strong for attack as for counterattack (this was expected, with regards to the playing style!). Its strength does not rely on calculations accuracy, and lowers in the endgame, especially weakened by the lack of standard endgame positions knowledge.

Novag Emerald Classic

Year: 1996
Programmer: Dave Kittinger
CPU: H8 @26.6/2Mhz
ROM: 32Kb
Elo level: 1970 (1872 FIDE)
CMhz: 8.65
Rperf: 105%
KT: 1755
Square size: 1.1"

This computer is on the verge of expert level, thanks to the 32K Kittinger program powered by a slightly overclocked H8 CPU running at 13.3 Mhz. While showing close statistical performance to the hereafter GK 2000, it outdoes it as far as chess skills are concerned, being thoroughly strong at any stage of the game. Its playing style is somewhat passive, rather positional, often leading to one of those two endings: if its opponent keeps the game under control, the Emerald Classic tends to slowly get extinguished, and ends up losing or drawing without having fought much. On another hand, if it takes an advantage, it starts attacking quite convincingly, and wins. It is a nice item as well, with a pleasant finish, yet a disadvantage is that the LCD display is pushed away from one's eyesight and, above all, lying flat thus uneasy to read, unless one uses the board on a coffee table. I bought it €85, a fair price.


Before performing the Khmelnitsky tests, I spotted more chess skills in this program, compared to its rival GK2000. Well, this is confirmed, with over 100 more KT points achieved! On another hand, I thought it was evenly strong, while the test underlines some weaknesses in opening and endgame, and particularly a lack of theoretical endgame knowledge. The skills profile is relatively atypic as, while strong tactics and capacity for recognizing threats are usual for programs, the prominent weakness for defense is surprising (on par with the Excellence and the Systema Challenge, so one category underneath!). This is consistent with the feeling I shared of a toneless play if under domination. The weak attacking skills confirm the noticed passivity (but this trend is fairly universal) whereas the capacity for counterattacking is outstandingly pronounced. Its expert skills domain is the middlegame...

Mephisto Milano v2.00

Year: 1993
Programmer: Ed Schröder
CPU: 65C02 @4.9Mhz
ROM: 64Kb
Elo level: 1985 (1887 FIDE)
CMhz: 4.9
Rperf: 109%
KT: 1723
Square size: 0.96"

I much appreciate Ed Schröder's programs... So, to do him full credit, the Rebell 5 being his first joint work with H&G was a bit alone in my collection. At the other end of this collaboration period, this Milano v2 (software version, the device has been upgraded with a 'Nigel Short' ROM) is one of the latest chess computers authored by Schröder, and the ultimate version of his 8 bits 6502 software, the best of class using this type of processor. Roughly 200 Elo points above the Rebell 5, using the same CPU, is quite impressive! The Milano is a nice looking device, quite flat, with a restrained design, offered with two white chessmen sets (light grey or chromium-plated) and a travel chess set as well (2D magnetic pieces). A cover casing is available to protect the chessboard/keyboard/display face while travelling or for safer storing. This casing smartly includes magnetic areas to easily store the 2D pieces (and a writing pad to track your games). In short, a very well designed chess computer, accomplished, sturdy, offering a number of software features (training, game post-mortem analysis, emulation of an opponent of selectable Elo level...). In addition to the 'Nigel Short' ROM providing twenty or so Elo points and a playing style known to be slightly more active, this one I bought €74.95 on German eBay features a nice enhanced display:




The "Nigel Short" program obviously comes from the Rebel 5 lineage, but with progress in nearly all domains. The Rebel 5 peak performances (openings, strategy) are kept unchanged, while the enhancements over other domains result in a smoother, more mature profile. The calculations ability made no gain, this was not unexpected: same processor and speed; and the evaluation function must have gone more sophisticated, which is not in favor of pure calculations strength. The most noticeable progresses lie in the middlegame skills, the tactical patterns recognition, the defense and the endgame theorical knowledge; even if this last domain remains weak with regards to the overall playing level.

Novag Citrine

Year: 2006
Programmer: Dave Kittinger
CPU: H8 @20Mhz
ROM: 56Kb
Elo Level: 1992 (1894 FIDE)
CMhz: 13
Rperf: 104%
Square size: 1.47"

I didn't buy this nice Citrine (€250 on French 'le bon coin') for its program, experience proves it is very close to the Emerald Classic. A small difference lies in its roughly 50% faster processor, and a slightly wider opening book. No, the real difference is with the playing comfort using the rather large auto-sensory wooden chessboard, and above all with the connectivity to the PC software Arena, offering a huge choice among chess engines, now usable as direct opponents on the chessboard. You just need to enable the 'referee mode' on the Citrine to disable the original program and substitute the Arena engine, including MessChess emulations of chess computers (I selected around 150 of these to set them in my Arena pool of engines). Then you can forget the PC in the background, it is no use watching the screen as the engine moves are reported by the blinking leds (and this can be usefully completed using Arena's feature for vocal announcement of moves). It is really top to use! A few drawbacks to be pointed out: the display module is not very handy, unreadable while lying flat (you absolutely must find or knock up a small stand to set the convenient slope) - but you can also play without - and the necessary cabling for PC connection, designed for a serial connector and thus requiring a USB or Bluetooth adaptor to connect a decently recent PC. But the Citrine remains the most affordable way to connect a nice auto-response board to a PC, and as a bonus, it is a dedicated chess computer as well.

Saitek GK 2000

Year: 1992
Programmer: Frans Morsch!
CPU: H8 @20/2Mhz
ROM: 16Kb
Elo level: 1994 (1896 FIDE)
CMhz: 6.5
Rperf: 108%
KT : 1648
Square size: 0.99"

A 16K amongst 32K and larger! I bought this chess computer bare (without pieces, mains adapter, manual nor original packaging) for price no doubt a bit high on German eBay (€70). Fortunately it runs perfectly, and it finally inherited the Saitek/Mephisto Chess Challenger 10Mhz set of chessmen. I was looking forward to add to my collection a H8 microcontroller; I had none at that date. Here the H8 is clocked by a 20Mhz quartz, reprocessed by a divider to provide 10Mhz at CPU level; the computing power exceeds the one of a 6Mhz 6502. Frans Morsch's program is impressive with its tactical strength, it is based on Fritz 1 and fully benefits from the H8 speed. Its playing style shows the characteristic features of computer chess, including some weakness in strategy. It is the Mephisto Europa big brother, and the strongest 16K program!


 
Being a strong player once leaving the openings book enables engaging games on a solid ground, but its playing level gets back to rather mediocre during middlegame and endgame, with a worthy of note very weak knowledge of standard endgame positions. It is neither a great strategist nor a strong calculator; and even less a great assailant. On another hand, it does efficiently spot threats and tactical patterns, to mightily counterattack. Avoid mistakes in order to reach the endgame, and you will beat it!



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