Intel 80286 microprocessor family

The second generation of x86 16-bit processors, Intel 80286, was released in 1982. The major new feature of the 80286 microprocessor was protected mode. When switched to this mode, the CPU could address up to 16 MB of operating memory (previous generation of 8086/8088 microprocessors was limited to 1 MB). In the protected mode it was possible to protect memory and other system resources from user programs - this feature was necessary for real program multitasking. There were many operating systems that utilized the 80286 protected mode: OS/2 1.x, Venix, SCO Xenix 286, and others. While this mode was useful for multitasking operating systems, it was of limited use for systems that required execution of existing x86 programs. The protected mode couldn't run multiple virtual 8086 programs, and had other limitations as well:

• 80286 was a 16-bit microprocessor. Although in protected mode the CPU could address up to 16 MB of memory, this was implemented using memory segments. Maximum size of memory segment was still 64 KB.
• There was no fast and reliable way to switch back to real mode from protected mode.

Currently the 80286 protected mode is not used by x86 operating systems. All modern 32-bit x86-based operating systems use 80386 protected mode that was introduced by next generation of Intel x86 processors.

The Intel 80286 microprocessor included new protected mode and all real-mode instructions that were introduced by 80186/80188 processors. Execution time of many real-mode instructions was reduced.