THIS AIN'T NO DISCO The Story of CBGB. By RomanKozak. Photographs by Ebet Roberts. 143 pp. Boston: Faber & Faber.

BENEATH the Palace flophouse on the Bowery, a former derelict bar exists that now has its history written, complete with a scholarly discography. It's CBGB - mecca of punk rock and hard-core music. Roman Kozak, from 1976 to 1983 an editor of Billboard, takes us through the early days (in the mid-1970's) when the ''shock of the new'' included musical headliners such as the Ramones, Blondie, Television, Talking Heads and Patti Smith.

In reading this lively account, we find out that the owner, Hilly Kristal, slept in the back room for two years and even formed a moving company to help support the financially troubled bar. We discover that the initials CBGB-OMFUG stand for ''country, bluegrass, blues and other music for uplifting gourmandizers.'' Mr. Kristal originally intended his club to present country-and-western entertainers, but after the Mercer Arts Center collapsed, the new ''psycho-sexual'' rock-and-roll bands were desperately searching for a new performance space. Terry Ork, who managed Television, provided advice and connections that proved invaluable in getting the hot new groups to play at CBGB.

Everyone ages - even the new wave. The author uses the recollections of the musicians, their managers and the staffers to convey their special relationship with this funky bar. If keeping the plethora of names straight creates a small problem, the cast of characters listed in the front will help. For the most part, vivid anecdotes keep these reminiscences from bogging down. For example, we glimpse a show by the Plasmatics that featured ''a six-foot-six guitarist with a blue mohawk hairdo who wore a dress . . . mock executions, a shotgun . . . and other mayhem. After the band got more popular it would blow up automobiles onstage.''

So it goes - from the Ramones to the Plasmatics to the hard-core groups of the 80's. The young skinheads who flock to Sunday matinees form the current big scene. They slam-dance to hard-core music, and most aren't old enough to drink at the bar (anyone over 16 can be admitted). Who else would have them? The bums still panhandle outside and the bar is still seedy, but some of the underage kids who used to sneak in a few years ago are now performers themselves -among them, the popular group Murphy's Law. If you've ever had your eardrums blasted at CBGB, you will enjoy ''This Ain't No Disco.''