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The AMD 80386 is a second-source and later independently manufactured implementation of the 32-bit 80386 architecture, preserving full IA-32 compatibility while extending x86 from its earlier 16-bit form into a true 32-bit platform with 32-bit general-purpose registers, 32-bit offsets, protected mode, paging, and a flat 4 GiB physical address space. Like Intel’s 80386, it supports virtual 8086 mode, hardware-enforced privilege levels, descriptor-based segmentation, and two-level page translation, providing the architectural foundation required for modern multitasking operating systems and virtual-memory environments. AMD produced both 386DX-class parts with a 32-bit external data bus and 386SX-compatible derivatives with a 16-bit external bus for lower-cost systems, while maintaining backward compatibility with earlier 8086 and 80286 software. Technically, the AMD 80386 is best understood not as a distinct new microarchitecture but as AMD’s fully compatible implementation of the processor generation that made x86 definitively 32-bit.