a$.$ On a hypothetical processor, there is a direct port addressing capability, in which a $20-$bit port address is part of the instruction, and an indirect port addressing capability, in which the instruction references one of the $20-$bit general purpose registers, which contains the port address. How many ports can the microprocessor address in each I$/$O addressing mode?

$1\mathrm{.}52=3$

b$.$ A particular system is controlled by an operator through commands entered from a keyboard. The average number of commands entered in an $5-$hour interval is $50.$ Suppose the processor scans the keyboard every $50ms.$ how many times will the keyboard be checked in an $6-$hour period?

$2$

c$.$ Let $SS=C800H,CS=8480H,SP=FFFFH$ and $IP=C846H.$ Calculate the physical address of the memory in each segment?

$1\mathrm{.}52=3$

d$.$ How many Memory chips of size $256K8$ are needed to develop a memory of size $4Mx32.$ Show the address range.

$1+1=2$