HOLLYWOOD — Call it the great network divide.

The just-concluded 2001-02 season developed into a battle between the haves and have-nots, with NBC and CBS combining to claim the season’s 20 most popular entertainment series, according to Nielsen.

Both ABC, whose year-to-year declines were steep but hardly a surprise, and Fox, which faced more roadblocks than anyone expected, were left out in the cold. These nets were down double-digit percentages from a year ago, while NBC was up slightly and CBS was down a smidge.

Overall, it was another victory for the Peacock in the vital demos like adults 18-49 and 25-54. Net, which also was tops in total viewers, actually surprised itself at how well it performed.

“We were expecting a very tight race between us and Fox, even with the Olympics being there,” NBC’s Scott Sassa says. “To have a 33% margin (over Fox in adults 18-49) is a real big surprise, and we couldn’t be happier about it.”

Fox edged out CBS for second in adults 18-49 (4.0 to 3.9), but the Eye clearly had more momentum at season’s end and has a shot at the silver medal next season.

Both weblets had reason to celebrate about the season, with UPN up double-digit percentages across the board and the WB stabilizing and riding lots of late-season momentum despite losing its No. 3 show of a year ago (“Buffy the Vampire Slayer”).

Here’s a look at other trends of the past season:

CABLE READY — Basic cable has been making inroads vs. the broadcast networks for years, but next season it is projected to outdraw the Big Four for the first time.

During any average minute of primetime during the 2001-02 season, the number of viewers watching the major nets (ABC, CBS, NBC and Fox) was only slightly more than those watching all of basic cable (44.7 million vs. 43.7m). This represents a 3% year-to-year decline for the Big Four and a 12% gain for the cablers.

As the broadcast nets like to point out, though, this is not the result of gains for the top 10 cable outlets, but more a function of the number of basic cablers mushrooming.

MAXIMIZING MINIS — Turns out the miniseries isn’t dead; the key may be simply airing fewer of them.

The nets broadcast just six miniseries during the season — half the number of the past two years — and there were no repeats of the head-to-head mini battles we’ve seen.

Multipart standouts included “Stephen King’s Rose Red” on ABC and “Living With the Dead” on CBS.

STAYING UP LATE — By offering up weak 10 p.m. competition on most nights, ABC and CBS allowed NBC to take a stranglehold on the 10:30 half-hour leading into local news.

In the May sweep, for example, promising Monday meller “Crossing Jordan” and new Friday heavyweight “Law & Order: SVU” helped NBC to an average 7.3 rating among adults 18-49 from 10:30 to 11. That compares with a measly 3.3 for both CBS and ABC.

No wonder CBS, at least, is making a big push next fall to address the 10 o’clock hour.

GOING TO THE WELL — After a “Carol Burnett Show” reunion spec delivered boffo ratings last November, reunion specials began popping up everywhere by May sweeps.

NBC, which had planned to revolve its May sweep around its 75th anniversary anyway, was able to tap into some of that nostalgia with successful specs, but CBS drew well less than half of the “Burnett” aud with its “Mary Tyler Moore Show” reunion, and ABC’s trips back to “Laverne & Shirley” and “That’s Incredible” just smelled desperate.

THIS WELL HAS DRIED UP — Once the hottest thing on the air, gameshows quickly lost their fizzle.

ABC’s “Who Wants to Be a Millionaire” continued its fall from grace the quickest, and regularly finished fourth or worse in its timeslot. NBC’s “Weakest Link” says “goodbye” as a regular.

Both quizzers, which seemed to have “celeb editions” every time you turned them on, will now turn their focus to syndicated versions, and are expected to air only in a limited form during primetime next season.

REALITY RALLIES — Second editions of Fox’s “Temptation Island” and ABC’s “The Mole” may have fizzled early in the season, but CBS did pretty well with “The Amazing Race” and “The Bachelor” gave ABC a much-needed late-season jolt.

CBS’ “Survivor” remains the genre’s crown jewel, even if it isn’t quite a phenomenon after four editions.