Memory protection: Before memory allocation, you need to protect the operating system from user processes, and protect user processes from other user processes. Two methods can be used for memory protection
: 1. Set up a pair of upper and lower limit registers in the CPU to store the lower and upper limit addresses of user jobs in the main memory. Whenever the CPU wants to access an address, the values of the two registers are the same. Ratio, judge whether there is any crossover.
2: Realize this protection through relocation register (or base address register) and boundary address register. The relocation register contains the smallest physical address value, and the boundary address register contains the maximum logical address. as follows
