$ProcessorType is a string giving the architecture of processor on which Mathematica is being run.
Typical values are "x86", "PowerPC", "SPARC", "MIPS", "PA-RISC" and "AXP".
$ProcessorType specifies the basic instruction set used by the CPU of your computer.
Computers with the same $ProcessorType may not be binary compatible.
See Section 2.14.5.
See also: $MachineType, $OperatingSystem, $System.
New in Version 3.