I386

The Intel 386, originally released as the 80386 and later renamed i386, is the third-generation x86 microprocessor developed by Intel. It is the first 32-bit processor in the line, and the first to implement the full IA-32 microarchitecture, marking a significant increase in capabilities while maintaining full compatibility with legacy code. Pre-production samples of the 386 were released to select developers in October 1985, while mass production commenced in June 1986. It was the central processing unit (CPU) of many workstations and high-end personal computers of the time. It began to fall out of public use when i486 processors became increasingly popular in the early 1990s, while in embedded systems, the 386 remained in widespread use until Intel finally discontinued it in 2007. Compared to its predecessor the Intel 80286 ("286"), the 32-bit i386 was compatible with the existing library of 16-bit applications created for earlier PCs, while also extending the architecture from 16-bits to 32-bits, extending the addressing to support up to 4 GB of memory, and adding an on-chip MMU allowing for easier virtual memory and paging implementation. The all-new virtual 8086 mode (or VM86) made it possible to run one or more real mode programs simultaneously virtualized under a protected mode operating environment. The i386 instruction set, programming model, and binary encodings are still the common denominator for all 32-bit x86 processors, which is termed the i386 architecture, x86, or IA-32, depending on context. Over the years, successively newer implementations of the same architecture have become several hundreds of times faster than the original 80386 (and thousands of times faster than the 8086).