There are four basic techniques of dance-music DJing: the overlay, the quick cut, the echo blend, and the extended remix. And there may be no one better versed in those basics then Grandmaster Flash, one of the last performing originals, who’s coming to Avalon this Friday to support his first CD in years, the ffrr release Essential Mix: Class Edition. Not even Flash remembers who invented each of these basics, but it’s widely accepted that the dub mix (an extended and more comprehensive version of the echo blend) was devised by François Kevorkian between 1980 and 1982. The rapid-fire version of the extended remix — called "scratch mixing" by its early practitioners, is also generally attributed to one revolutionary DJ: Grandmaster Flash, as the turntablist in Grandmaster Flash and the Furious Five. Flash’s scratch mix worked the beat portion of a record; his scratches sounded like ferocious drumming, an intensity of passion that rocked any melody it touched.

Flash, whose real name is Joseph Saddler, is happy to take credit for the scratch mix. "Before me," he recalls over the phone from his New York home, "there was nobody taking 10 seconds of music, two copies of it, and repeating it back and forth, seamlessly, quickly. Rapid fire. It was 1974 [at which time the young Mr. Saddler was just 16], and the downtown DJs were doing long, smooth extended mixes. Mine were rapid-fire. I did it in my house. Just for fun. I had to take the best part of the record and extend it. Then in 1977, I tried it out in the park. I was ridiculed. Then I taught a few new DJs to do it and I added vocal accompaniment. This is still 1977, now. The Furious Four joined with me, and then we did our records with Bobby Robinson."

By the time that "Superappin’," Grandmaster Flash and the Furious Five’s first Robinson record (on the ENJOY label), came out, it was 1979, and the Sugarhill Gang’s "Rapper’s Delight" and Fatback’s "King Tim III (Personality Jock)" were already well known. So did Flash really invent the rapid-fire extended remix? He may well have; about six months before these first rap records appeared, Arthur Baker — then a struggling disco-tape-creating kid from Boston — told me that I had to come to the Bronx with him, that there were kids rapping to instrumental tracks, rapping in front of beats that he said he’d never heard anything like. They were "mobile jocks, house-party types," who were doing it on something he called a "beatbox." Unfortunately for the historical record, Arthur did not repeat to me the name of even one of these beatbox DJs. Who knew? It was enough to know that they were "mobile jocks." All of us in that era’s disco circles knew that "mobile jocks" were innovators to the core, tricksters, surprisers. While the big-name DJs were creating, polishing, and dramatizing their plush mixes to the sound of Philadelphia soul and European disco, these turntable swingsters were establishing their own disco circles at neighborhood house parties. Where the downtown DJs used elegant Philly soul, Chic, Savannah Band, and Euro, the house-party crowd favored the spit and shove of funk and boogie.

The media, who identified disco with leisure suits and John Travolta, ignored the mobile jocks. Yet they and the dancers they DJed for were the driving force of disco, the unselfconscious seekers of Saturday-night joy and sweaty body movement. And Flash was among them, big-time. That much is certain. Right there, in "Superappin’," Flash’s five MCs proclaim him "the best-known."

Still, there was something missing in Flash’s visibility momentum. Five names get writer’s credit on the 12-inch single’s label, but not Flash. Yet his MCs — Cowboy, Raheem, Mister Ness, Kid Creole, Melle Mel — chant "Flash is on the beatbox!/Flash is on the beatbox" over and over, trying as hard as they can to identify him: their DJ, a DJ with a "beatbox." Unhappily for Flash’s reputation as a rapid-fire remixer, on "Superappin’ " no rapid-fire mixing or scratching appears. His beatbox work is smooth and unhurried and never distorted. It’s not even clear that the song’s rhythm track is performed by him. Its New York funk-style guitar riffs and droll, low bass lines — redolent of Cymande’s "Bra," a house-party favorite — may well have been played by Bobby Robinson’s in-house rhythm section, Pumpkin and Friends. Still, though Pumpkin and Friends get credited on the label of a contemporary single, "Rappin’ and Rockin’ the House," by the Funky Four Plus One More, there’s no mention of them on the label of "Superappin’."

Even if back in 1979 Flash was not using in the studio the rapid-fire mixes that he asserts were his invention, he was definitely attracting a ton of attention in live shows at Harlem’s Audubon Ballroom. To quote what he says in his new record-company bio: "To my amazement I seen license plates from Philly, Connecticut, Washington." In the same bio, downtown DJ Johnny Dynell — then an art-disco wild kid — remembers it like this: "I went with a friend to this church basement and I saw this battle with Grandmaster Flash, Hollywood, all those early guys. And Flash was DJing with his toes. He was scratching. . . . He just rocked my world."

In the end, Flash was blindsided by his rivals. At the end of 1980, during which his group moved over to Sylvia Robinson’s Sugar Hill label and cut "Freedom," a song almost identical to "Superappin’," there appeared Vaughn Mason’s "Bounce, Rock, Skate, Roll" — a rapped reworking of Chic’s "Good Times." Overnight, house-party DJs were using the 12-inch single itself as a scratch device. Every copy in sight got bought up and scratched to death. The scratch mix was out and about, and it was taking over, and Flash was behind the curve. Scratch mixing now began to attract an entirely new audience: the house-party kids in and around New York, who invented a dance for it — called "hip-hop" — that was just as rapid-fire as the mixes. After the house-party kids came the more-adventurous rock audience — some Joy Division types, a New York Doll or two, a fair number of Ramones fans, and a lot of Television, Richard Hell, and Blondie alumni (and alumnae). All of them were looking to put the rhythm back into rock, to free it from the stultifying immobility of 1970s art rock and metal. They took up the scratch mix and its special dance, and if the new public knew only the Vaughn Mason types, the Johnny Dynells among them knew that Flash was scratch’s man. So did Blondie, who in "Rapture" talked all about Flash, his moves, his beats, his music.

Blondie at least knew who Flash was; most folks thought that he was one of the Furious Five’s rappers. He wasn’t. At the beatbox, he stood behind the MCs, like a drummer but far less conspicuous — unless you happened to see him up close. When at the 1981 Billboard Music Seminar in New York City various DJs gave a demonstration of scratch mixing to a small but packed room, Flash demonstrated all that and more. In addition to machine-gun scratch mixing, he used voice drop-ins, overlays, and quick cuts, and because the songs that he reworked were mostly smooth, dressy, and cool — Chic’s "Good Times" was all the rage with scratchers then — his handiwork seriously ripped them up. His mixes were a combination of bad-ass destructo party and tipsy prom-queen happiness. It was time for him to make his record, to take back his magic and his scene.

Any doubt about who Flash was and why ended with the early 1981 release of "The Adventures of Grandmaster Flash on the Wheels of Steel." Checking in at 7:18, it was the first time any record label had ever recorded and released a DJ playing a long mix. Here were rapid-fire remixes, of all kinds of disco, pop, and funk, and here was scratching galore, in a variety of applications: buzzsaw riffs, vocal imitation, quick cuts, echo blends. At 8:30, the B-side’s "The Party Mix" was even longer. Although both sides were credited to Grandmaster Flash and the Furious Five, all the drama lay in the mixes. It was the beginning of what today is a rapidly growing, full-length-CD segment of the recording industry: the live-on-record DJ mix.

In hip-hop, the years 1982 and 1983 belonged to Flash and the Furious Five. Twelve-inch singles like "The Message," "The Birthday Party," and "White Lines" got played in lots of venues, and on FM stations, where no disco had ever been allowed. And then it was over. Run-DMC’s "It’s like That," with its rhythm box enhanced, and greatly embroidered, by studio rhythms and sound effects, took over. By comparison, Flash’s fast and multiplex mixes sounded lean and all too literal. The Furious Five broke up, and Flash was . . . well, where was he?

"It was a learning experience," he says. "It was bittersweet. My business was not straight during all those years I was making all that great music. So I decided to relax for a minute. Decide what I wanted to do next. So I ended up doing radio and TV. And I did DJing. I was musical director for the Chris Rock show [on HBO]. As a DJ I backed Chris. Then I went back to touring. And I found an attorney who protects me from doing anything silly."

Today, Flash is 44 years old. He has six kids. He has a studio in his basement. He still tours. An electronics student as a kid, he has designed a mixer he calls the Empath. "It’s to be unveiled at the electronics show in Atlantic City in August. It can access more machines and can be readjusted to a DJ’s own specs, for EQ-ing and in how its sliders work. It can be reconfigured. Everything in it is exactly where he wants it to be."

DJs will doubtless flock to the Empath, which is made by Rane Company. Dancers will more likely prefer Flash’s new CD. Here the man himself, 20 years after his annus mirabilis, does his stuff again. The 17 tracks of Essential Mix: Class Edition consist of disco, funk, soul, and pop songs from the 1970s and 1980s — Flash calls them "my favorites" — ranging across the full spectrum of disco tastes. Nineteen-eighties club kids will find Denroy Morgan’s "I’ll Do Anything for You," Indeep’s "Last Night a DJ Saved My Life," and D Train’s "You’re the One for Me." Nineteen-seventies house-party goers will once again move to Cymande’s "Bra," Jimmy Castor Bunch’s "It’s Just Begun," and Fatback Band’s "I Found Lovin’." Pop (Nu Shooz)’s "I Can’t Wait" links with Rockers Revenge’s disco-reggae remake of Eddy Grant’s "Walking on Sunshine" and Weeks & Co’s "Rock Your World." And the sweet disco silk of MSFB featuring the Three Degrees’ "Love Is the Message" says hello to James Brown’s "Give It Up or Turn It a Loose." Blondie’s "Rapture" appears, as does Afrika Bambaataa’s 1982 hit "Planet Rock."

The CD opens with the echo-blend intro from "Wheels of Steel," then shifts to the soft girly tweet of Nu Shooz’s song. As the intensity of the songs heats up, so does Flash’s handicraft; by the time the session reaches Denroy Morgan, Cymande, and Rockers Revenge, he’s overlaying the rhythm, quick-cutting lavishly, from the splashy peak of one beat to the peak of the next, adding in echo effects to immerse the dancer in the boil of the music. Flash never experiments here, never takes his new session into the previously unthinkable, but he doesn’t need to. Restraint is the key — that, and a love of nuance that embraces the glow of disco in all its ineffable grace. Essential Mix is not at all the buzz music of a brash kid boasting in the park the power of his fingers, Rather, it’s the ongoing steadiness of a man who wants the joy to last and the step of the rhythm to keep on stepping. And isn’t that, after all, the permanent good news common to every one of those far-off mobile jocks of whom Flash is now the last performing remnant?

Grandmaster Flash plays Avalon, 36 Lansdowne Street, this Friday, May 31. Call (617) 931-2000.