Dynamic RAM

The Apple I shipped with four kilobytes of dynamic RAM (an extra four kilobytes was a $120 option). At the time, most microcomputers relied on static RAM, which used extra transistors to hold data and did not need to be refreshed as frequently as dynamic RAM. Woz was able to create a more sophisticated circuit design that worked around the need for constant refreshing, enabling him to use the smaller–and cheaper–dynamic RAM chips.

Video and Keyboard Interfaces

At the time, many microcomputers relied for input and output on manual switches or electromechanical typewriters called teletypes. Woz built video and keyboard interfaces right onto the circuit board so users could “avoid all the expense, noise and maintenance associated with a teletype,” in the words of one of the first Apple I advertisements. Although, as Damer points out, contemporary mainframes had cathode-ray-tube monitors and Xerox’s Palo Alto Research Center was developing the revolutionary Star computer, the Apple I was the first device that most people today would recognize as a personal computer.

Cassette Interface

Preliminary Apple I designs had no way to store data such as programs (they needed to be typed in every time you turned on the microcomputer), so Jobs and Woz soon added a cassette interface. This method of storing data, a precursor to the floppy disk and CD-ROM, already existed in the microcomputer market, but Woz created a design that used fewer chips and less power, cost less, and offered better data transmission speed. “Classic Woz,” says Damer.