The Intersil 80C286 is a static CMOS version of the NMOS 80286 microprocessor. The 80C286 is an advanced, highperformance microprocessor with specially optimized capabilities for multiple user and multi-tasking systems. The 80C286 has built-in memory protection that supports operating system and task isolation as well as program and data privacy within tasks. A 25MHz 80C286 provides up to nineteen times the throughput of a standard 5MHz 8086. The 80C286 includes memory management capabilities that map 230 (one gigabyte) of virtual address space per task into 224 bytes (16 megabytes) of physical memory. The 80C286 is upwardly compatible with 80C86 and 80C88 software (the 80C286 instruction set is a superset of the 80C86/80C88 instruction set). Using the 80C286 real address mode, the 80C286 is object code compatible with existing 80C86 and 80C88 software. In protected virtual address mode, the 80C286 is source code compatible with 80C86 and 80C88 software but may require upgrading to use virtual address as supported by the 80C286's integrated memory management and protection mechanism. Both modes operate at full 80C286 performance and execute a superset of the 80C86 and 80C88 instructions. The 80C286 provides special operations to support the efficient implementation and execution of operating systems. For example, one instruction can end execution of one task, save its state, switch to a new task, load its state, and start execution of the new task. The 80C286 also supports virtual memory systems by providing a segment-not-present exception and restartable instructions.