A system has a Translation Lookaside Buffer (TLB) that has a reach of 1 MB . TLB reach is defined as the total amount of physical memory that can be accessed through the TLB entries. The paging system uses pages of size 4 KB . The virtual address space is 64 GB and physical address space is 1 GB . If each TLB entry stores a 4-bit process id, page number, frame number, and a 2-bit control field, then the size of the TLB (in bytes) is $\_\_\_\_$ . (answer in integer)

Note: $1 \mathrm{~K}=2^{10}, 1 \mathrm{M}=2^{20}, 1 \mathrm{G}=2^{30}$

Consider contiguous allocation of physical memory to processes using variable partitioning scheme. Suppose there are 8 holes in the memory of sizes $20 \mathrm{~KB}, 4 \mathrm{~KB}$, $25 \mathrm{~KB}, 18 \mathrm{~KB}, 7 \mathrm{~KB}, 9 \mathrm{~KB}, 15 \mathrm{~KB}$, and 12 KB . Assume that no two holes are adjacent. Two processes P1 of size 16 KB and P2 of size 9 KB arrive in that order, and they are allocated memory using the best-fit technique. After allocating space to P1 and P2, the number of holes of size less than 8 KB is $\_\_\_\_$ . (answer in integer)

Note: $1 \mathrm{~K}=2^{10}$

Consider a system that has a cache memory unit and a memory management unit (MMU). The address input to the cache memory is a physical address. The MMU has a translation lookaside buffer (TLB). Assume that when a page is evicted from the main memory, the corresponding blocks in the cache are marked as invalid.

For a given memory reference, which of the following sequences of events can NEVER happen?

Consider a demand paging system with three frames, and the following page reference string: 1 2 3 4 5 4 1 6 4 5 1 3 2 . The contents of the frames are as follows initially and after each reference (from left to right):

The *-marked references cause page replacements.

Which one or more of the following could be the page replacement policy/policies in use?