18-548/15-548 Fall 1998

Homework 3:
Virtual Memory

Due Wednesday September 16, 1998

Virtual Memory

Problem 1:

Consider a virtual memory system with the following characteristics:

• Page size of 16 KB
• Page table and page directory entries of 8 bytes per entry
• Inverted page table entries of 16 bytes per entry
• 31 bit physical address, byte addressed
• Two-level page table structure (containing a page directory and one layer of page tables)

a) What is size (in number of address bits) of the virtual address space supported by the above virtual memory configuration?

b) What is the maximum required size (in KB, MB, or GB) of an inverted page table for the above virtual memory configuration?

Problem 2:

The 548LX is a uniprocessor having up to a maximum of 64 MB of addressable physical memory. The virtual memory and TLB have the following attributes:

Sketch a block diagram of how the virtual address is mapped into the physical address (assuming a TLB hit). Be sure to label arrows showing exactly which/how many of the address bits go where, and how many bits are in each of the 3 fields in a TLB entry.

18-548/15-548 home page.