$1.$ Explain the basic concept behind memory$-$mapped I$/$O$.$

$2.$ What is meant by $$synchronous communication.$$ Give a practical example from

the real world.

$3.$ What is meant by $$asynchronous communication.$$ Give a practical example from

the real world.

$4.$ What is meant by $$polling$$ or $$polling mode$$ in I$/$O$.$ Give a practical example from

the real world.

$5.$ What is meant by $$interrupt$$ or $$interrupt mode$$ in I$/$O$.$ Give a practical example

from the real world.

$6.$ I$/$O devices typically have associated with them a data register and a status register.

Explain what these two registers are. Give an example of how they are used in I$/$O$.$

For the next exercise, you need to assemble your code and run it on the LC$-3.$

$7.$ Write an LC$-3$ Assembly language program that checks the value in memory

location x$5000$ to see if it is an alphanumeric character $($in other words, characters $\text{'}$a$\text{'}$

through $\text{'}$z$\text{'},\text{'}$A$\text{'}$ through $\text{'}$Z$\text{'},$ or $\text{'}0\text{'}$ through $\text{'}9\text{'}).$ If the value in location x$5000$ is one of

these characters, the program prints the character to the screen. If it is not, the

program prints nothing.