Yo! MTV Raps! aired 6 days a week for most of its run (1988-95). DJ Fab 5 Freddy (Fred Braithwaite), who was immortalized in the lyrics of Blondie's 1981 hit, "Rapture", served as the Saturday host, traveling on location. Doctor Dre (not to be confused with Dr. Dre) and Ed Lover hosted from the studio on weekdays. Rap was a hot music genre at the end of the 80's and well into the 90's.
Yo! occupied the 10-11 (ET) berth on Saturday mornings, giving teens and young adults an alternative to network fare such as Pee-Wee's Playhouse & Alvin & the Chipmunks, to use a couple of examples. During Spring Break in March, Yo!, like the rest of MTV's core programming, would be on location, usually from Daytona Beach, but in those cases, it was Ed & Dre filling in, as I do not recall Fab 5 doing a Saturday show during Spring Break.
With MTV having all but abandoned music entirely, the clips available on YouTube are all that's left of a classic. Here's the intro to the weekday edition: