80x86 refers to a series of processors created by Intel. This is the series of processors used in most computers that run MS-DOS and Microsoft Windows. Members of the series incluse 8086, 80286, 80386, 80486, and the Pentium series. The first processors only had 16-bits of address space and this caused the memory limitations found in legacy operating systems such as MS-DOS. Later processors in the series introduced 32-bit addressing giving the ability to address 4 gigabytes.