Practice Exercises $9\mathrm{.}1$ Name two differences between logical and physical addresses. $9\mathrm{.}2$ Why are page sizes always powers of $2?9\mathrm{.}3$ Consider a system in which a program can be separated into two parts: code and data. The CPU knows whether it wants an instruction $($instruc$-$ tion fetch$)$ or data $($data fetch or store$).$ Therefore, two base$-$limit register pairs are provided: one for instructions and one for data. The instruction base$-$limit register pair is automatically read$-$only, so programs can be shared among different users. Discuss the advantages and disadvan$-$ tages of this scheme. $9\mathrm{.}4$ Consider a logical address space of $64$ pages of $1,024$ words each, mapped onto a physical memory of $32$ frames. a$.$ How many bits are there in the logical address? b$.$ How many bits are there in the physical address? $9\mathrm{.}5$ What is the effect of allowing two entries in a page table to point to the same page frame in memory? Explain how this effect could be used to decrease the amount of time needed to copy a large amount of memory from one place to another. What effect would updating some byte on one page have on the other page? $9\mathrm{.}6$ Given six memory partitions of $300KB,600KB,350KB,200KB,750KB,$ and $125KB($in order$),$ how would the first$-$fit, best$-$fit, and worst$-$fit algorithms place processes of size $115KB,500KB,358KB,200KB,$ and $375KB($in order$)?$