On the Intel 386 architecture the page table entry is a 32 bit number which composed of these fields:

• 0: Present bit
• 1: Read/Write bit
• 2: User/Supervisor bit
• 3: Write Thru bit (for 486 and above)
• 4: Cache Disable bit (for 486 and above)
• 5: Dirty bit
• 6: Accessed bit
• 7-8: Reserved
• 9-11: For use by the operating system
• 12-31: Contains the physical address of the page frame.