Hack: The Apple I
A look back at the original motherboard: Steve Wozniak’s 1976 Apple I.
Before the iPod, the Macintosh, or even the formation of Apple Computer Company on April Fool’s Day 1976, there was the Apple I. Designed by Steve “Woz” Wozniak, then an engineer at Hewlett-Packard, it was less a personal computer than the bare essentials of one: the circuit board you see in the image at left is the Apple I (buyers had to hook up their own keyboards, displays, and power supplies). This computer, the very first Apple I made, was first used in a math class at Windsor Junior High School in Windsor, CA, in 1976 and donated to the LO*OP Center, a nonprofit educational organization run by Liza Loop. In total, only about 200 of the Apple I motherboards were made. In 1977, Apple introduced the groundbreaking Apple II–which could be bought simply as a motherboard or assembled with case, keyboard, and power supply.
Low Cost as a Design Priority
“Woz liked the challenge of doing more with less,” says Damer. Wozniak pored over integrated-circuit specifications and engineered the Apple I so that different processes could share the same chips, reducing the overall part count. This, plus the use of cheaper items such as a $20 MOS Technology 6502 microprocessor rather than the more common $175 Motorola 6800, enabled him and Steve Jobs to offer the Apple I for the somewhat affordable price of $666.66 (“Woz liked repeating numbers,” says Damer), about $2,400 in today’s dollars. According to Damer, “Woz was a total idealist–he wanted everyone to have access to computers.” Loop, who is also the director of the History of Computing in Learning and Education Project, agrees: “Woz wanted this simple, low-cost design so that the Apple would be affordable for students and teachers.”
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Most microcomputers at the time used multiple circuit boards: one for the CPU, one for the video interface, one for the memory, and so on. “Woz took all the constituent parts of a microcomputer and put them all on one board,” says Sellam Ismail, the proprietor of VintageTech, which maintains an archive of computer artifacts and history. Not only did this make construction cheaper and reduce power consumption, but it allowed users to build compact, all-in-one enclosures for the Apple I, leading to the unified design of the Apple II and the original Mac.
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.
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.