On one day in July 1988, the top executives of Boston's largest employer, money market giant Fidelity Investments, gave Mayor Raymond L. Flynn a gift.

At least 15 of the firm's executives, many of whom had never given to the liberal Democratic mayor before, donated $7,300 to Flynn's campaign coffers at a fundraising breakfast.

Every Fidelity managing director gave to the mayor that year, many coughing up the legal maximum - at a time when the firm was negotiating with city officials to build a controversial new downtown Boston skyscraper.

Within weeks of the fundraiser, city officials joined Fidelity executives at a press conference to heap praise on the construction proposal.

For Flynn, whose name has been mentioned as a vice presidential candidate, accepting financial contributions from those with business before the city is common practice, the Boston Herald found in a computer examination of seven years of his campaign records.

Out of the Flynn donors whose occupations were identified in the years 1987-89, nearly 90 percent were comprised of city employees, contractors and developers, downtown business interests, city no-bid contractors and others with direct financial ties to City Hall.

Hundreds of police officers, including a significant percentage of the department's top brass, gave to the mayor despite department regulations directly forbidding police employees from contributing to any candidate.

The Massachusetts Secretary of State is currently contemplating legal action against Mayor Flynn's administration.

More than 23,000 donations were logged by Flynn during his first two terms of office, but the state law governing campaign financing does not require listing each donors' occupation.

By the middle of last summer, Boston Herald City Hall Bureau Chief Joe Sciacca and I had roughed out a plan to probe Flynn's finances, obtained management support and contracted with a data entry firm to place the mayor's donor lists into a computer database.

We brainstormed for hours about how to get around the city's refusal to provide computer records to the public - despite the state's legal opinion that such records should be accessible.

Though we had only the tiniest inkling of what we would find last summer, Flynn's $1.3 million cash warchest begged for close examination by a team of investigative reporters - especially after Flynn's name surfaced in rumors as a possible presidential candidate.

But uncovering the identities behind the anonymous names on Flynn's extensive donor lists proved infinitely more challenging.

Only names and addresses served as clues to the identity and possible motives - of the contributions to the candidate with some of the deepest pockets in Massachusetts.

In fact, city officials seem to delight in frustrating reporters' attempts to obtain electronic records. Just last fall, a city department head provided a Boston Herald reporter with a five-foot high stack of computer printouts to fulfill a request for a computer record. "That's all you're going to get," said the official.

For our story, we settled on a dual strategy. We pursued computer records from independent agencies on the periphery of City Hall, where the public records law apparently means more than it does in the mayor's inner sanctum. And, reluctantly, we decided to pay several thousand dollars to enter a paper copy of the city payroll into a database.

Progress was slow, but encouraging. A helpful source in the city Liquor Board gave us diskettes containing the names of the owners and managers of every bar, tavern and restaurant in Boston.

Sure enough, a number of persons associated with the more prominent establishments seemed to be loyal donors, especially the politically connected owner of the city's leading chain of nightclubs.

But soon, it became all too apparent that, while matching bar owners and other similar groups to Flynn's donor list gave us an interesting start - there was no similar source of data that would identify persons associated with real estate developers and key downtown business interests.

Our sources had told us the owners and managers of these firms were Flynn's top backers, but without a means of identifying them by a rapid computer search, we would have to resort to combing telephone and business directories by hand.

I was lamenting this fact one day with a veteran fundraiser. "It's too bad it's not a federal campaign," he said. Federal law requires candidates to list the occupations of their financial backers.

Then an idea hit. Why not match Flynn's campaign donors to federal records - already on computer - to obtain occupations for the people who gave to Flynn?

Massachusetts Gov. Michael Dukakis' unsuccessful presidential bid in 1988 provided us an unusually large pool of Democratic contributors in the state who were likely to have also given to Boston's Democratic mayor.

It seemed simple on paper. I created a file of the approximately 21,000 records of persons living in Massachusetts who have given to various federal candidates in the years 1987 through 1989.

A gruesome series of technical exercises followed.

First, the federal record is structured so that there is only one field containing the last name, first name, middle initial and any title or salutation. This would not do.

Using the yWrite word processing software, which includes a powerful programming system, I was able to edit the records in such a way that the names were broken into four fields. Still, this process took the better part of a week because of the large size of the file and the seemingly endless series of steps it required.

Next, comparing the federal records against the Flynn donors presented problems of accuracy. The computerized Federal Election Commission records do not include contributors' street addresses, making it more difficult to ensure that two matching names are indeed the same person.

To ensure the results were not polluted with erroneous matches, I only considered two names a legitimate match when first, last and middle names were identical, and when titles such as "Jr." were the same.

I followed this step with an intensive audit of the resulting file match to ensure that the results were accurate. For example, I manually examined every case in which the names matched, but the cities in which they lived were not the same. Hundreds of records were dropped from consideration to ensure accuracy.

Finally, owing to the structures of both campaign files, the search produced a large number of duplicate records, which had to be eliminated to produce accurate results. Here, Elliot Jaspin proved helpful by writing a simple program for the XDB SQL database system that deleted the duplicates.

After more than two weeks of sweating over the keyboard, we were rewarded with a gold mine.

Nearly 2,700 donations were now identified by occupations.

It was almost immediately apparent that real estate, development and construction employees dominated the list of Flynn donors that had been produced. One employer showed up numerous times: Fidelity.

A Fidelity year-end report added the names of a few executives who had not given donations to federal candidates.

Our paper's library revealed that Fidelity's fundraiser for the mayor coincided with discussions for its proposed skyscraper.

The clips also showed that the project had met with considerable opposition from historic preservationists because of its size. Despite the problems with the plan, city officials heaped praise on the project when it was first publicly announced.

In all the computer searches allowed us to identify the occupations of about half of Flynn's donors - or their immediate family members - in the years 1987-89.