Macintosh (1984 to present)
Development status: Open
Platform size: 210+
The Macintosh platform first emerged in 1984, and it has been with us in some form or another ever since. Over these past 22 years, the platform has seen three major hardware shifts (those between 68K, PowerPC, and x86 CPUs) and one major operating system shift (between Classic OS and OS X).
While some could argue that these three CPU types constitute three separate platforms (and technically, they do), Apple accompanied each hardware shift with emulation layers that preserved backwards compatibility, thus maintaining the spirit of Macintosh between hardware revisions.