Skip to main content

You are not logged in. Your edit will be placed in a queue until it is peer reviewed.

We welcome edits that make the post easier to understand and more valuable for readers. Because community members review edits, please try to make the post substantially better than how you found it, for example, by fixing grammar or adding additional resources and hyperlinks.

Required fields*

2
  • \$\begingroup\$ I'm not sure these counts as different versions. Don't they just correlate to different system configurations.? \$\endgroup\$ Commented Aug 19, 2017 at 23:47
  • 3
    \$\begingroup\$ @Uriel: Running a block of machine code with the CPU in 16-bit mode, 32-bit mode, or 64-bit mode is the machine-code equivalent of running python2 vs. python3 interpreters on the same Python program. New x86 CPUs always include a mode that's compatible with older CPUs (this is their only excuse for using such a convoluted hard-to-decode machine-code format!), but 386's 32-bit protected mode and x86-64's long mode really are new versions of x86 machine code. Long mode even removed some opcodes, making them invalid. \$\endgroup\$ Commented May 18, 2019 at 21:06