The Macintosh computer was named after the McIntosh apple, a favourite of Jef Raskin one of the Mac's creators. The McIntosh spelling could not be used as another electronics company was using the name so Macintosh was used by Apple for their computer.
Macintosh is a brand of computer that are used around the world. Apple makes the Macintosh computers and they are based in California, USA.
Mac OS
Apple's Mac OS X is legally only used on Apple Macintosh computers.
When IBM took over the market in personal computer from Apple, Apple developed the Macintosh. The Macintosh sported a new 3-inch disk drive that was faster than the 5-inch drives used in other machines, including the Apple II. Apple sold 70,000 Macintosh computers in the first 100 days.
There is no definition for performa in the dictionary; there was an Apple computer series in the 1990s called the Macintosh Performa.
Mac OS
An Apple computer, or a Mac, is basically a computer designed and built by Apple Inc. and running a version Mac OS version. Apple's current computer line is the Macintosh; they also produce the iPod, although the iPod is rarely referred to as a "computer." Apple Inc. (then known as Apple Computer) was one of the early personal computer manufacturers. Their first big entry in the market was the Apple II, which became one of the top personal computers before the IBM PC appeared. Those days birthed the term "Apple computer," since the word "Apple" designated both the manufacturer and the name of the computer. The current version of Mac OS X is OS X 10.8 Mountain Lion
The operating system used on Macintosh computers is written primarily by the programers at Apple. However they incorporate innovations from outside Apple such as 'Cover Flow' which were popular with Macintosh users. The original operating systems upon which the latest versions of the Apple operating system are based are 'NEXTSTEP/OPENSTEP.' and 'BSD,' which is a derivative of 'UNIX.'
The internal codename of the first model of the machine was "Macintosh", it used a Motorola 68000 microprocessor and had 128K of RAM. When released it was named the Apple Macintosh. When the next model, the Apple Macintosh 512K (with 512K of RAM) was released the original model was renamed the Apple Macintosh 128K. Later models were also called Macintosh, but over the years the name shortened in usage to Mac.
I assume you're referring to the Apple logo. If so, Steve Jobs worked in a apple orchard as a kid. This is where he came up with the name Macintosh referring to the Macintosh Apple. He therefore used the Apple logo for his computers. The I in iMac stands for Internet and the Mac Stands for Macintosh.
Apple. It is generally used most on the macintosh.