Quarterback Scott Bull, who started five games for the San Francisco 49ers last season, has one month to whip his twice-operated-on knee into shape if he hopes to play for the National Football League squad in 1979.

The fourth-year quarterback injured his knee the second time in the 49ers' final game last season, requiring surgery. Because of Bull's slow recovery, the club placed the former Arkansas signal-caller on the active-physically disabled list, which means the 49ers must trade hime, waive him or put him on the injured reserve list by Aug. 21.

Bull will remain with the club until then, continuing his extensive rehabilitation program of running and lifting weights. The 49ers have four other quarterbacks in camp, veteran Steve DeBerg and rookies Joe Montana, Mike Cordova and Gary Forystek. Coach Bill Walsh has said he will keep three quarterbacks.

Veteran all-pro guard Joe Delamielleure of the Buffalo Bills did not need an agent to negotiate a five-year extension of his contract yesterday, which he says "is equal to that of the highest paid offensive linemen in the league."

Delamielleure, a first-round pick in 1973 who has been selected an all-pro four straight seasons, said he negotiated the terms of his new contract in 30 minutes.

Denver Bronco quarterback Craig Morton had no complaints about being fined by the club after he was arrested Friday by Colorado State University police for allegedly driving while under the influence of alcohol.

"I guess I didn't use very good judgement," said Morton,who is competing with Norris Weese and Craig Penrose for the Bronco quarterback position.

"I guess I had too many beers. I hadn't had anything to eat so I guess that made it worse."

Morton, 36, a 15-year veteran, was bailed out by Coach Red Miller, who posted $425 bond. "The guy made a mistake. He's been disciplined under our rules and we'd like that to be the end of it," Miller said.

Morton, who describes himself as a born-again Christian, faces a court appearance Aug. 27. He is involved in several religious activities in Denver.