Complex sentence: He wrote several early Apple II programs, served as a beta tester for Apple hardware and software, and Wozniak designed the Disk II floppy disk drive system after Markkula found that a checkbook-balancing program he had written loaded too slowly from a data cassette.
Split into simpler sentences: He wrote several early Apple II programs and served as a beta tester for Apple hardware and software. Wozniak was motivated to design the Disk II floppy disk drive system after Markkula found that a checkbook-balancing program he had written loaded too slowly from a data cassette.