Tuesday night, the NBA playoff game between Phoenix and Portland on CBS averaged an 8.8 national rating and a 16 percent audience share twixt 9 and 11:45 p.m... .

Although it was all repeats, ABC's comedy lineup that night didn't have much trouble winning the evening, while NBC finished second ...

Cable News Network, with paying customers in 90 countries around the world these days, celebrates its 10th year on the air tomorrow ...

"ABC World News Tonight With Peter Jennings" won the evening network race for the 20th week in a row with a 9.3/20 last week, compared with an 8.5/18 for "CBS Evening News With Dan Rather" and a 7.8/17 for "NBC Nightly News With Tom Brokaw." Tom and Peter, by the way, will be broadcasting from San Francisco Monday night as President Mikhail Gorbachev winds up his visit to the United States out on the West Coast ...

More worrisome news for CBS -- that rumble out of Louisville, where the CBS affiliate WHAS, which dominates the local news, is reportedly flirting with ABC, which has had to settle for a UHF in that 46th largest TV market ...

An ABC spokesman yesterday declined to comment on the speculation ...

TV RATINGZZZZ

Following are the top 20 network prime-time shows last week, ranked according to the percentage of the nation's 92.1 milllion TV households that watched, as measured by the A.C. Nielsen Co. A share represents the percentage of actual sets-in-use tuned to a particular program when it aired.

RATINGS........................SHARE...NETWORK

1 18.7 Newhart.......................29......CBS

2 18.3 Cheers.........................32......NBC

3 17.7 Murphy Brown...................27......CBS

4 17.2 Designing Women................26......CBS

5 16.1 Roseanne........................26......ABC

6 15.9 A Different World...............29......NBC

7 15.8 Killing in a Small Town.........26......CBS

8 15.7 The Cosby Show..................30......NBC

9 15.5 Unsolved Mysteries..............28......NBC

..15.5 Voices Within: Truddi Chase II..25......ABC

11 15.0 The Golden Girls...............31......NBC

...15.0 Wings..........................26......NBC

13 14.9 Empty Nest.....................31......NBC

14 14.4 Cheers (Weds.).................25......NBC

15 14.2 60 Minutes.....................35......CBS

16 14.1 Major Dad......................24......CBS

17 13.8 Coach..........................22......ABC

18 13.4 America's Funniest Home Videos.28......ABC

19 13.3 The Simpsons...................26......FOX

20 13.2 The Wonder Years...............22......ABC

Although CBS came within a whisker of winning the May ratings sweeps from NBC, the latter enjoyed a comfortable victory margin for the week ending May 27 ...

For the week, NBC averaged an 11.1/21, compared with a 10.4/19 for ABC and a 10.0/19 for CBS ...

In other highlights, the season finale of "Twin Peaks" on ABC tied for 23rd, the "Night of 100 Stars" special on NBC was 26th and the Barbara Walters special on ABC that led into the "Twin Peaks" finale was 33rd, with a 10.9/18, which those NBC research meanies yesterday said was her lowest special ratings ever. Honestly, NBC! ...

NBC's "Last Flight Out" movie was 36th, CBS's People Magazine on the air special was 60th ...

Lowest rated show: FOX's "Tracey Ullman Show" in 78th ...

Now This There's been an odd battle of the local on-air promos in recent days, TV Column fans, after Channel 4 introduced a spot last week to "thank" area viewers for making them "number one at 5, 6 and 11" in the recently completed May ratings sweeps ...

That prompted a letter from WJLA executive vice president John Long to WRC general manager Allan Horlick in which he made a "formal request that you suspend airing the promo" because it's "a clear misrepresentation of the facts" ...

John was upset because Seven's "In Person" from 5 to 5:30 averaged a 6.4 Nielsen rating and an 18 share, compared with a 5.9/16 for Four's "Live at 5" and a 6.0/17 for Nine's "Eyewitness News" for that same half hour ...

To sharpen the point, over the weekend Seven launched its own promo bragging that "Washington's most exciting news program became the number one news program at 5 o'clock" ...

Looked at another way, however, all three network affiliates were tied between 5 and 6 with 6.4 ratings (although WJLA lists its own 5:30 to 6:30 news show as a separate hour, leading into the network news) ...

For his part, Horlick dismissed Long's complaint as "trivial ...

"I can read the numbers: There's a three-way tie ...

"He should have sent his complaint to WUSA," said Horlick, "which is still opening each one of its newscasts every night by claiming it's Washington's number one newscast. Nine's been number one in this town for many years, yet we've beaten them at 11 five {sweeps} ratings books in a row and two in a row at 6 and we're tied at 5" ...

From 5 to 6 in the May Nielsen book, WRC and WUSA both did 6.4/17s, while WJLA averaged a 6.8/17 from 5:30 to 6:30. Between 6 and 7, WRC averaged an 8.1/19, compared with a 7.8/19 for WUSA ...

In late news, Monday through Sunday, WRC averaged a 10.8/24, compared with a 9.8/21 for WUSA and a 6.1/13 for WJLA. Channel 5's 10 o'clock news averaged an 8.2/14, Monday through Saturday ...

Each local Nielsen point represents 17,278 TV homes ...

Before Channel 4 gets all puffed up, however, it should be noted that Channel 9's news looks a lot better in Arbitron during May, where it won at 5, 6 and 11 -- and by considerable margins -- just like the announcer says every night. Each ARB point represents 17,017 TV homes ...

If you're real good, TV Column fans, we'll expand on the exciting local ratingzzz reports in future columns ...

On Another Front

CBS affiliate Nine has acquired the Arsenio Hall show, currently being aired on Channel 20 in this market, starting in January 1991 ...

The Paramount Domestic Television late night show will be followed on Nine by another Paramount syndicated program that debuts that month, the 30-minute "The Party Machine With Nia Peeples" ...

On Nine, Arsenio will air from 11:30 to 12:30 Mondays through Fridays. Peeples will follow at 12:30 except on Friday nights, when it will be seen at 1:30 a.m. following "Music Video Connection" ...

Currently Nine is airing "Divorce Court" at 11:30, followed by CBS programming. That arrangement will continue until January, according to general manager Hank Yaggi ...

"Divorce Court" will move to 1 a.m., after Peeples, in January, leading up to CBS News's "Nightwatch" ...

Channel 20's current contract with Paramount for Arsenio ends in January. Ironically, the Paramount broadcast group subsidiary, NewTel, now controls 79 percent of WDCA ...

With the purchase of the two late night Paramount entries, Nine is taking on a definite Paramount cast next season. With the loss of King World's "Wheel of Fortune" to Channel 7 next September, Nine will pick up Paramount's "Entertainment Tonight" for the 7:30 weeknight timeslot in the fall ...

And there is a chance that Maury Povich's new one-hour talk show, to be produced by Paramount, just might fit into the 4 p.m. weekday timeslot on Nine currently occupied by a very early one-hour news show ...

WDCA vice president Dick Williams is somewhat philosophical about the loss of Arsenio to the VHF station ...

"We're sorry to see it go but it's not the end of the world. We built up the Washington audience for Arsenio and we're not going to roll over and play dead because he's gone. We've been a hell of an opening act for this guy for the last two years and now he wants to play Vegas" ...

He pointed out that Hall is an equity partner in the show with Paramount and "it's obvious he's calling part of the shots. It's a business decision; he's got a chance to be on a VHF in this market, he has a piece of the action" ...

On the UHF independent, Hall has regularly averaged a 4 rating between 11 and midnight, sometimes even getting a 5 in the Arbitron book. On Nine, the audience potential is considerably greater ...

Yaggi would not reveal terms of his deal with Paramount ...

Williams said no decision has been made on what will replace Arsenio Hall next winter but program manager Sandy Pastoor promised the alternative "will be exciting" ...

NBC has decided to wait until Monday, June 11, to introduce its new and not-so-new "Today" show cast members to the viewing public ...

But the NBC affiliates, who will be meeting here at the National Theatre and J.W. Marriott headquarters starting Sunday, will meet old/newcomers Joe Garagiola, Faith Daniels and Katie Couric on Monday morning when the trio joins Bryant Gumbel, Deborah Norville, Willard Scott and Gene Shalit plus executive producer Tom Capra at the theatah ...

Originally, the new trio was also to be introduced to viewers on Monday's broadcast. The show originates from in front of the Air and Space Museum on the Mall through Wednesday morning next week ...

Why the delay? "It's 'cuz we're on the road" next week, Capra explained yesterday. "We'll be better organized in the studio" ...