Until television history gets the Ken Burns treatment (preferably by Ken Burns), this four-part PBS pledge-bait documentary series should warm the nostalgic cockles of Baby Boomers' TV-lovin' hearts. A generous sampling of clips and interviews with some of TV Land's most beloved personalities fondly and reverently recall television's golden age and the pantheon of mold-breakers and template setters. "Late Night" confers King status on Johnny Carson, but it does pay tribute to his trailblazing predecessors, Steve Allen, with his unpredictable blend of wit and silliness, and Jack Paar, equally unpredictable (he once quit his show on the air after a tiff with network censors), who mastered the art of conversation. "Sitcoms" spotlights five groundbreaking series,The Honeymooners,Make Room for Daddy,I Love Lucy,The Andy Griffith Show, andThe Dick Van Dyke Show. "Variety" begins withThe Ed Sullivan Showand proceeds through a host of entertainers who fronted their own shows, culminating in the gold standard,The Carol Burnett Show. "Game Show" is a winner with hilarious, rarely seen clips of classic game show moments (it's always a naughty delight to hear Paul Lynde'sHollywood Squareszingers).There will be quibbles. Ernie Kovacs is but one glaring and bewildering omission, and icons such as Carol Burnett are missing in action. The series often blurs the line between being a pioneer and merely popular. But talking heads don't come any more entertaining than Tim Conway, Barbara Eden, Andy Griffith, Mary Tyler Moore, Dick Van Dyke, Betty White, Jay Leno, Jim Nabors, Marlo Thomas (talking about her father, Danny, but herself something of a pioneer), Joyce "Trixie" Randolph, Dick Cavett, Regis Philbin, and Tony Orlando (Tony Orlando?).Pioneersbreaks little new ground. Most of these stories have been told better elsewhere, and certainly less clichéd ("The winds of ambition were blowing Johnny westward"). But there is much to treasure in the well-chosen clips, including Johnny Carson's earliest talk- and game-show gigs, Carl Reiner's failed pilot,Head of the Family, which becameThe Dick Van Dyke Show, and an earlyHoneymoonersclip with Pert Kelton as Alice.  There are still pioneers breaking new ground, but this welcome series is a reminder of those who paved the way. And if nothing else, in this era of reality television, it's a great escape to a bygone era.--Donald Liebenson