Expected Levels. Total hardness in freshwater is usually in the range of 15 to 375 mg/L as CaCO3. Calcium. hardness in freshwater is in the range of 10 to 250 mg/L, often double that of magnesium. hardness (5 to 125 mg/L). Typical seawater has calcium hardness of 1000 mg/L, magnesium.
Part of the Storage management glossary: A physical address is a binarynumber in the form of logical high and low states on an address busthat corresponds to a particular cell of primary storage(also called main memory), or to a particular register in a memory-mapped I/O(input/output) device.
Use the 10 most significant bits of the address to find the page table in the page directory (the top level page table). The next 10 bits are the index into the page table (the lower level page table). Use the address in that page table entry to find the physical page address. The last ten bits are the byte address into the page. By the way, you would probably find a lot more people who would understand this type of question at an OS oriented site such as OSDev.