Question

Explain the bounds registers approach for partitioned memory management and also give the major disadvantage of the bounds registers approach

Answer 1

Bounds register approach

* The major goal of Bounds register approach is to provide memory protection. This helps in access control.

* Hardware used for the virtual memory allocation

* Bound registers are two registers whose contents are used to denote an area of memory where there is access control

* Base bound registers is associated with a segment of data or code defines the position in the physical memory of word zero for the segment so called the base and the number of words available to that segment. So called the bound or the limit.

* Whenever a process tries to acess the memory segment, the hardware of the system checks that address of the word lies within the range 0 <--- word address < bound. Then add the address to the value in the base register to get the physical address.

Disadvantages of Bounds register:--

-- Each process must be contigously allocated in the physical memory

-- Must allocate the memory that may not be used by the process

-- No partial sharing -- cannot share limited space of address space