About half of small and midsize companies using computers in Tokyo have not yet adapted their systems to cope with the "Year 2000 problem," or Millennium Bug, which is expected to wreak havoc on companies with computers unable to process 21st century dates, a metropolitan survey says.

The survey, released Friday by the Economic and Labor Bureau of the Tokyo Metropolitan Government, comes less than two years before the next century. Many old computer systems are not designed to deal with dates beyond 1999 because of a coding oversight that reads only the last two digits of a year. The result could be disastrous -- an invoice with a due date in 2000 could be mistaken for 1900, and be mistaken as 100 years overdue.

Of 3,720 small and midsize companies that received the questionnaire, 779, or 20.9 percent, responded. Of those, 81 percent said they are using computers. And of that number, 52.3 percent said they have not yet corrected their systems.

Only 19.8 percent said they had already made corrections; another 21.7 percent said the coming of the new century will not affect their system.

Among reasons for not dealing with the problem, 37.2 percent said they are tied up with their main business; 26.5 percent cited costs; 11.5 percent said software companies they entrusted with the work are slow to respond.

The slowness of software companies indicated that they have been kept busy due to many similar requests from other companies, the survey said, warning that small and midsize companies should deal with the problems as early as possible, before the software firms are inundated with requests as 2000 approaches.