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Rightly or wrongly, many judge a computer by its ability to play a good game of chess, and every self-respecting micro has at least one chess program to offer. Many commercial mainframe computers are not above a quick game of chess either and national pride is put on the line in organised International Computer Chess Tournaments - micros too have their own International Chess Competitions.

Several chess programs have been available for the Spectrum for some time, so the appearance of Intelligent Software's Cyrus Is Chess program in July accompanied by the slogan "based upon the program which won the European Micro Computer Championship 1981" must arouse some curiosity - especially as it comes with a 16-page User's Manual, and is marketed by Sinclair who already have a chess program in their Spectrum Catalogue. The Cyrus program is designed by David Levy, the Scottish International Chess Master and noted chess computer expert whose programs can be found in several dedicated chess computers.

How does the Cyrus program differ from its contemporaries? It is one of the few chess programs that fit into either the 16K or 48K models. Side A of the cassette has two copies of the 16K version whilst side B has two copies of the 48K version with some additional features. Side A (16K) loads in 90 seconds and Side B (48K) in two minutes. The graphics are clear and they are moved using the cursor keys: a flashing square is moved to the piece to be moved then 'entered'; the flashing square is then moved to the destination square and 'entered' again. The cursor method requires five key movements - the same number as the more usual E2-E4 'ENTER' method - but for some reason the cursor actually moving the pieces seems closer to 'over the board confrontation'.

Level 1 ... 2 secs
Level 2 ... 5 secs
Level 3 ... 10 secs
Level 4 ... 20 secs
Level 5 ... 30 secs
Level 6 ... 1 min 15 secs
Level 7 ... 3 mins
Level 8 ... 5-12 mins
P1 ... Computes until 'Mate' found
P2 ... Computes until 'Mate' found
P3 ... Computes until 'Mate' found

Levels or sides can be changed during the course of the game and the board can be turned around but of more interest is the fact that the level times are faster than those stated for many 'dedicated' chess computers to be found in the shops - this should mean that you can have a worthwhile game of chess without waiting too long for the computer to reply to your move. The Cyrus program also enables the player to take back moves, up to 80 moves in the 16K program and up to the beginning of any longer game in the 48K version. The 48K program also enables a player to ask the computer to take its move back and play its next best move, then second best move, then third, etc. This means that you can 'cheat' but of more importance to the chess enthusiast is the fact that you can use your computer to analyse various openings and positions. In addition, by tapping the R key you can ask Cyrus to automatically replay the game for both sides up to the present position, be it a mid-game position or a final mate. This is rather like watching Mastergame on television.

In demonstration mode Cyrus will play both sides through a complete game at any pre-set level and, as a bonus, there is a Human v Human mode which enables two players to use Cyrus as a chessboard and pieces. This also means that a school or chess club can use Cyrus instead of a demonstration board at a quarter of the normal cost.

An impressive list of features - but how well does Cyrus play? On loading, Cyrus automatically sets itself to level 2 (response time 5 seconds). The manual states that the 48K version might be quicker in the opening than the 16K program as it has a larger opening 'book' i.e. it has been programmed with a larger repertoire of popular openings to respond quickly to anticipated moves.

Impressive for a five second response! Cyrus then can prove a formidable opponent.

As a further measure, Cyrus was pitted against two dedicated chess computers - Morphy Encore (£140) and Mini Sensory-Advanced (£80) both of advanced design which 'think' in their opponent's time. At approximately the same response levels and playing Black in each case:

Cyrus Level 3 defeated Mini-Sensory Advanced Level 2 (29 moves).

Cyrus Level 6 had the better of the exchange and was heading for a win endgame against Morphy Encore Level 3 (44 moves).

To be fair, Morphy Encore has a lot more reserves to call up having nine levels, including two at tournament level but the fact that Cyrus did so well says a lot for the Cyrus Program and a Mate-in-Three Chess Problem was solved in a very acceptable three minutes.

One irritating feature of the 16K version is that it does not display the Menu of fifteen options on the screen with the chess board but fills up the lower area of the screen with a rather distracting 'I S Chess' Logo. Playing strengths of the 16K and 48K versions are the same.

Apart from the larger opening 'book' and 'menu' display on screen the 48K version offers:

1. The option of using a printer to print every move as it is made, to produce a record after a complete game or to print out the current board position.
2. A game may be saved on tape and re-entered into the computer's memory later.
3. The colours of the screen display can be changed.
4. In problem mode, the 48K will display 'NO MATE FOUND' if it cannot solve a problem in the number of moves stipulated.

An unusual feature for both the 16K and 48K versions is that Cyrus will announce a DRAW if no pawn is moved or piece captured during a sequence of 50 moves of it both sides move the same pieces backwards and forwards over the same squares three times running. This is in accord with the rules of chess but is a feature not to be found in many other computer chess programs. In conclusion, Cyrus is a strong yet flexible chess program for your Spectrum you will be fascinated by this one!