According to this post: https://retrocomputing.stackexchange.com/questions/219/80286-can-switch-from-real-mode-to-protected-mode-but-why-not-back https://retroc

According to this post: https://retrocomputing.stackexchange.com/questions/219/80286-can-switch-from-real-mode-to-protected-mode-but-why-not-back https://retrocomputing.stackexchange.com/questions/219/80286... attempting to set the PE bit back to zero has no effect: > The CPU is put into protected mode by setting the PE bit in MSW using the LMSW or LOADALL instructions. Clearing the PE bit has no effect using either of those instructions, thus it is not possible to switch back to real mode.