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.