A new computerized 911 emergency system in Montgomery County, the first of its kind in the Washington area, is expected to help police officers and firefighters dramatically lessen crucial response time.

The key feature of the $1 million state-of-the-art system is the automatic appearance of the name, address and phone number of the person to whom the phone belongs on a computer screen at the county's emergency communications center in Rockville.

Police and fire dispatchers can instantly learn the location of callers having trouble communicating, such as children who do not know where they live, non-English speaking persons, or ill, frantic or confused callers.

In the past, dispatchers had to rely on the telephone company to trace such calls, a process that could take up to 30 minutes.

The automatic tracing feature would have reduced police response time in a 1978 case, for example, when an Olney woman who was being stabbed called 911, said police communications supervisor Bernie Keller. The woman kept saying "send the police," but could not communicate her address.

Police had to wait about 35 minutes for the call to be traced, Keller said. When they finally arrived at the woman's home, she had been stabbed about 20 times. She later died at a hospital, Keller said.

The installation of the new system last month involved rewiring of the 11-year-old 911 system to include 18,000 Montgomery residents living near county borders who have phone exchanges of either Prince George's, Howard or Frederick counties.

In the past, 911 calls from county residents with non-Montgomery exchanges went to the adjoining county before being transferred to Montgomery, causing delays of several minutes.

Montgomery is the first Washington-area jurisdiction to install the enhanced 911 system, said Jack Humphries, a manager for the four C&P telephone companies in Maryland, the District, Virginia and West Virginia that sell the system.

Prince George's, Fairfax, Arlington and Alexandria are expected to have identical systems operating by the first of next year and the District will follow in the spring, Humphries said.

The Washington metropolitan area is "in step" with the rest of the country in upgrading emergency communication systems, a phone company spokesman said.

There are 25 to 30 of the new 911 systems presently operating across the country, primarily in metropolitan areas.

In this region, new systems are on line in Howard, Carroll and Baltimore counties and in Baltimore City.

About 35 systems have been ordered by additional jurisdictions in the four states C&P serves, Humphries said. It takes about two years to collect the necessary data before a system can be used.

The data base of Montgomery's system contains all county residential and business phone numbers and addresses -- about 500,000 -- and is updated every 24 hours.

Montgomery generally will protect callers reporting crimes who request anonymity, said police communications supervisor Larry Bell. Exceptions to that policy include cases in which a caller has witnessed a serious felony, he said.

Automatic loss of anonymity "may have a deterrent effect" on citizen reports of emergencies, Bell acknowledged. "There are always a certain number of people that are always afraid. But the benefits are going to far outweigh this small detrimental factor," he said.

In addition to a caller's address and phone number, the primary fire, police and rescue stations serving an address now also appear on the 911 computer screen when a call comes in, eliminating the step of locating addresses and station responsibility areas on maps.

Officials also hope the automatic tracing feature will reduce the number of deliberate false alarms. There were 1,183 false alarms in 1984 alone.

Not only can lives and valuable equipment be lost in high-speed trips answering false alarms, but the public is jeopardized when equipment answering a false call is far from the scene of a legitimate emergency, said Marcine Goodloe, executive secretary of the Montgomery County Fire & Rescue Commission.

The new system will also help end confusion over duplicate street names and hasten the transfer of calls to other police authorities.

By punching a one-or-two-digit number, dispatchers can now transfer calls to local, park or state police. In the past, callers were simply told the seven-digit number of different police departments.

At present, the new system only reduces the processing time of 911 calls when a caller's information is incomplete, and it has no effect on the time between service dispatch and arrival at an emergency scene, said Jack Manbeck, chief of telecommunications for the county.

But time-saving computer functions currently being developed for a sophisticated CAD (computer-assisted dispatch) system, Montgomery's next step in improving emergency communications, will substantially reduce 911 call processing time when the system goes on line in 1987, communication officials said.

With the CAD system,, a 911 phone call will automatically produce the following information about the address on a computer screen: nearby available police or fire units; changes in surrounding road conditions; presence of hazardous materials; antipolice or weapons history; non-English speaking, elderly or infant residents; outstanding arrest warrants; utility information; or approved burning permits.

Such information must now be manually checked in files at the communications center or at local stations, which can cause delays.

With CAD, police officers or firefighters will be able to grab a computer printout of all pertinent data related to a particular address before heading out on a call.