It took less than a minute to run the program that assigned freshmen to upper-class houses, but the Class of 1990 will have to live with the results for the next three years.

And they'll learn those results this morning when envelopes containing the 1590 Yardlings' future addresses arrive on their doorsteps between 8:30 and 9:15 a.m.

More than a month after house-hunting season began with a panel on the housing lottery, a computer program matched 495 blocking groups to 12 residential houses in a few fateful seconds shortly after noon on Tuesday.

Only five houses filled up in the first round this year, Housing Officer Lisa M. Colvin said. However, a sixth house had only two slots left after the first round and no rooming group that was sufficiently small had listed that house as a second or third choice, she said.

One house filled up in the second round, and two filled up in the third, Colvin said, adding that another house had very few spaces left after the second round and no small groups had put it down as a third choice.

Four houses, including the two which were nearly full, had students randomly assigned to them, Colvin said.

College officials refused to release the order in which houses filled up. Assistant Dean of the House System Thomas A. Dingman' 67 said, "The masters of those houses that have not filled up by choice felt that a public record of that fact was not a helpful thing in building a community."

Only 76.4 percent of the freshmen were assigned to their first-choice houses, down from 80 percent last year. The remainder suffered the consequences of the College's "maximization of first choice" system.

If a rooming group's first-choice house was full by the time the computer reached its number, the computer skipped over the group to complete the first round of assignments. It returned to the unassigned groups' second choices after it had run the gamut of the freshmen's first choices.

Next year, 8.3 percent of the Class of 1990 will be living in their second-choice houses and 5.4 percent received their third-choice houses, Colvin said.

The remaining 9.9 percent of the freshman class did not receive any of their three choices. The program sorted these rooming groups by size from largest to smallest and then randomly assigned them to spaces in houses that were not yet filled, Colvin said. Last year, only 8 percent of the Class of 1989 were assigned to houses that were not among their three choices.

One reason fewer freshmen got their first choice "may be that people were putting down their real choices and there was less scheming," Dingman said.

In addition, the College's quota system may have affected which houses went random. The quotas require that the ratio of sophomore men to women be between 1:1 and 2:1. If a house had reached its quota for male or female sophomores, the computer would only accept members of the opposite sex.

Slow Starters

Although the computer program took almost no time to run, the housing lottery process started slowly for the Class of 1990.