MSW - Machine Status Word (286+ only)
│31│30-5│4│3│2│1│0│ Machine Status Word │ │ │ │ │ │ └──── Protection Enable (PE) │ │ │ │ │ └───── Math Present (MP) │ │ │ │ └────── Emulation (EM) │ │ │ └─────── Task Switched (TS) │ │ └──────── Extension Type (ET) │ └────────── Reserved └───────────── Paging (PG) Bit 0 PE Protection Enable, switches processor between protected and real mode Bit 1 MP Math Present, controls function of the WAIT instruction Bit 2 EM Emulation, indicates whether coprocessor functions are to be emulated Bit 3 TS Task Switched, set and interrogated by coprocessor on task switches and when interpretting coprocessor instructions Bit 4 ET Extension Type, indicates type of coprocessor in system Bits 5-30 Reserved bit 31 PG Paging, indicates whether the processor uses page tables to translate linear addresses to physical addresses - see SMSW LMSW