Parents of Arlington public school students will be getting fewer notes from the principal's office but more phone calls--from a computer that will then play a tape recorded message in any of three languages.

Special computerized telephone calling machines will be placed in each of the county's three high schools and its special vocational center at a total cost of $18,000 with the double aim of cutting the need for office help and giving parents more information about what's happening in the schools, especially about their children's absences.

The machines will be programmed to dial students' homes between 7 p.m. and 9 p.m. on the day an absence from a class has occurred and parents will be told of the absence and asked to send in a note. Homes also will be called periodically to alert parents to the number of absences accumulated.

The county has adopted tighter attendance policies this year that will strip students of credit for courses in which they accumulate more than eight unexcused absences.

The computer also will be used to dial homes with information about such things as the time and place of the next school dance, football game and PTA meeting.

"It's going to be notifying parents about good things and bad things," said school spokesman Dennis Smith.

The name and phone number of each student will be programmed into the machine along with instructions to deliver the message in English, Spanish or Vietnamese.

The system won't be foolproof: "Yes, kids may very well answer the phone," said Yorktown High Assistant Principal Brenda Glenn, adding, "and we'll have no way of telling if they answered it."

But she said human beings will phone the homes of chronic truants.