Computers have become a necessary tool in all laboratories involved in DNA sequence work. There has been a rapid increase in the amount of DNA sequenced, and the most recent issue of the European Molecular Biology Laboratory (EMBL) Nucleotide Sequence Data Library (release 10, 1987) contains almost 10 million base pairs in almost 9000 entries compared with the first release from 1982 containing half a million base pairs in 500 entries. The requirement for computers is obvious not only from the total amount of DNA sequenced, but also when taking into account the number of bases needed in order to organize a gene. The size of a standard gene with no intervening sequences is 500-1000 base pairs, whereas interrupted genes may be 10 times longer.