DOSBox/DOSBox-X has an excellement implementation
of a 386, 486, and pentium core.

What would help make the emulation complete are
additional cputype settings for DOS games or
programs that were too reliant on early processors.

cputype=8086                  Intel 8088/8086 emulation (no Invalid Opcode, no 186/286 instructions)
cputype=286                   Intel 286 emulation (no 32-bit instructions, no 32-bit protected mode, supports 286 LOADALL instruction)

Additional changes to the current DOSBox cores:

Configuration option to enable/disable FPU emulation. If you want to
emulate an early 386 with no 387 (which was common), then you can
disable FPU emulation to do that.

For cputype=386:
 - 386 LOADALL emulation
 - 386 floating point exception emulation (if not already there)
 - Make sure you can't toggle the AC bit. Mainline DOSBox had a bug where cputype=386 did not
   disable the AC bit and millions of DOS games and Windows 3.1 still thought they were running
   on a 486.

