Apple II

The Apple II was designed by Steve Wozniak, who aimed to create a fully assembled and user-friendly computer, unlike the bare circuit boards of earlier hobbyist machines. It was introduced at the West Coast Computer Faire in April 1977, alongside the Commodore PET and Tandy TRS-80, which together became known as the '1977 trinity' of personal computers.¹

Wozniak's design innovations included built-in BASIC, color graphics, and an open architecture with eight expansion slots, which allowed users to add peripherals and third-party cards. The machine was housed in a sleek plastic case, a departure from the metal or wood enclosures of its contemporaries.²

The Apple II used a MOS Technology 6502 microprocessor running at 1 MHz, with 4 KB of RAM initially, expandable to 48 KB. It featured a built-in keyboard, a cassette tape interface for storage, and a video output that supported text and color graphics. The machine's open architecture allowed for expansion cards, including floppy disk drives, printers, and modems.³

The Apple II's built-in BASIC, written by Wozniak, was stored in ROM and provided a simple programming environment. Later, Apple introduced AppleSoft BASIC, which was more advanced and became the standard. The machine also supported the Apple II Disk II floppy drive, which greatly enhanced data storage and sharing.⁴

The Apple II was a commercial success, selling over 5 million units over its lifetime. It became a standard in education, business, and home computing, and its popularity helped establish Apple as a major player in the industry. The machine's influence extended to software development, with the first spreadsheet program, VisiCalc, originally written for the Apple II, which drove sales to businesses.⁵

The Apple II series continued with several models, including the Apple II Plus (1979), Apple IIe (1983), Apple IIc (1984), and Apple IIGS (1986). The line was discontinued in 1993, but its legacy persists in the design philosophy of user-friendly, expandable personal computers.

One lesser-known fact is that the Apple II's color graphics were achieved through a clever trick: the video output used a composite signal that could produce colors by manipulating the phase of the color burst signal, allowing for 16 colors in high-resolution mode, though some were not true colors but artifacts.

Another obscure detail is that the Apple II's design was influenced by Wozniak's experience with the Atari game Breakout, which he helped design. He incorporated a similar approach to generating sound and graphics. Additionally, the Apple II's motherboard was designed to be as compact as possible, with components placed tightly together, which was unusual for the time.

The Apple II also had a built-in speaker that could produce simple tones, and programmers often used it to play music or create sound effects. The machine's cassette interface was notoriously slow, but it allowed users to save and load programs without expensive disk drives.

MOS 6502

An 8-bit microprocessor used in the Apple II and many other early computers.

AppleSoft BASIC

A version of BASIC developed by Apple, which became the standard for the Apple II.

Disk II

A floppy disk drive introduced by Apple in 1978, which used 5.25-inch floppy disks.

VisiCalc

The first spreadsheet program, originally released for the Apple II in 1979.