the 20th annual acm north american computer chess championship  despite entering ranked almost a class above the field, a last-round loss forced deep thought to settle for a first-place tie with hitech at the 20th annual acm north american computer chess championship. the five-round swiss- style tournament was held november 12-15 at bally's-reno in conjunction with supercomputing '89. it marked the twentieth consecutive year that acm has organized this major chess event. until 1988, the tournament took place at the annual acm conferences. in 1988 and again this year, however, the event was hosted by the joint acm sigarch/ieee computer society supercomputing conference. ten teams participated in the strongest computer chess tournament in history. every program was playing at least at the expert level.  this year's tournament offered $5000 in prizes. hitech and deep thought's programmers each won $2000 for their first-place tie while mephisto x and bebe's programmers split the $1000 third-place prize. in addition to the cash prizes, trophies were awarded to the first three finishers. a special trophy was given to mephisto x as the "best small computing system."  a technical session chaired by tony marsland was held during the championship. the topic of the session was endgame play by computers. once upon a time computers played the endgame particularly badly, but this is no longer the case. the session considered some of the improvements and some of the problems that remain.  david levy served as tournament director, returning after a layoff of almost a decade. he served as td for the first time in 1971, continuing into the early 1980s when his own programs began to compete. levy will take on deep thought in london in a four-game match in december.* in 1978, he won a bet made in 1968 that no computer would defeat him during the following ten years. this time he appears to be the underdog.  attending the championship as an honored guest was ben mittman. mittman was head of northwestern university's vogelback computing center during the years that slate, atkin, and gorlen's programs dominated the acm events. some give him credit for being northwestern university's greatest and most successful "coach." from 1971 through 1983, ben also was involved in the organization of the tournaments, from 1977 through 1983, ben served as the first president of the international computer chess association. he was also the first editor of what is now called the icca journal, the main journal for technical papers on computer chess.  this year the championship is scheduled to be a part of supercomputing '90 in new york city on november 11-14. the 1990 event will see the first major change in the tournament rules. for the last 20 years, the rules have specified that each player is given two hours to make the first 40 moves and an additional hour for each 20 moves thereafter. games frequently lasted more than six hours. this year, each computer will be required to make all its moves in two hours, thus guaranteeing that no game will last more than four hours. in addition to the main championship, a special endgame tournament will be held testing the programs' abilities in this special part of the game. for the first time at supercomputing '90, all games will be played during the day beginning at 1:oo p.m.---except for one 7:00 p.m. sunday evening game on the 11th. the event will be a five-round swiss-style tournament. for information contact professor monty newborn, school of computer science, mcgill university, 3480 university street, montreal, quebec, canada, h3a. 2a7.  monty newborn