Windows NT stopped supporting the Intel 80386 processor with Windows 4.0, which raised the minimum requirements to an Intel 80486. Therefore, the Intel 80386 technically falls into the category of “processor that Windows once supported but no longer does.” This series focuses on the portion of the x86 instruction set available on an 80386, although I will make notes about future extensions in a special chapter.[…]
As with all the processor retrospective series, I’m going to focus on how Windows NT used the Intel 80386 in user mode because the original audience for all of these discussions was user-mode developers trying to get up to speed debugging their programs. Normally, this means that I omit instructions that you are unlikely to see in compiler-generated code. However, I’ll set aside a day to cover some of the legacy instructions that are functional but not used in practice.