In the memo, Mr. Jobs told employees of the Cupertino, Calif., computer maker that he had a rare form of pancreatic cancer, called islet cell neuroendocrine tumor, which can be cured by surgery if removed in time.
The tumor was diagnosed in time, he said, and he won't require any chemotherapy or radiation treatment.
Mr. Jobs, who co-founded Apple in the 1970s, said he will return to work in September.
During his absence, Tim Cook, who heads operations, sales and Macintosh hardware at Apple, will run overall day-to-day operations.
"We shouldn't miss a beat," Mr. Jobs wrote in his note.
"I'm sure I'll be calling some of you way too much in August, and I look forward to seeing you in September."
Mr. Jobs ended his memo in a punchy manner, telling employees that he was sending his memo from his hospital bed, using his 17-inch PowerBook laptop and AirPort Express wireless node, which are Apple products.
Mr. Cook, in an interview, said that Mr. Jobs's doctors say his prognosis is "excellent."
Mr. Cook added that everyone at Apple "knows what we need to do. Steve is a very hands-on CEO and we've discussed on a weekly basis plans for the many many months ahead."
He said he expects Mr. Jobs to e-mail and call him frequently in August.
Bill Campbell, an Apple director, said he saw Mr. Jobs on Saturday and Sunday and that the CEO was "sitting up and very alert and animated."
Mr. Campbell said the board has "tremendous confidence in Tim and in the depth and quality of [Apple's] management team."
He said the board executed the plan that they had had in case of any emergency with Mr. Jobs, which was asking Mr. Cook to oversee day-to-day operations.
Mr. Campbell added that the board and Mr. Jobs also have a confidential succession plan in place.
Article comments
1 - Andrew Ian Dodge
Ouch, let's hope he gets well soon.