$1.$ a$)$ Define single programming and mul$$programming$.$

b$)$ Describe a scenario where mul$$programming might be be$$er than single programming. Note: You may use the internet to research any applica$$ons or describe an example from your personal experience.

$2.$ Suppose P$1,$ P$2,$ P$3,$ and P$4$ are ready to run $($in this order$).$ P$1$ executes for $4$me units, P$2$ executes for $5$me units, P$3$ executes for $2$me units, and P$4$ executes for $3$me units. Neither process invokes I$/$O$.$ Assuming that a $$mer interrupt occurs every $$me unit, fill in the table:

Time $($in units$)$

Running

Queue of Processes Ready to Run

$0+$e

P$1$

P$2,$ P$3,$ P$4$

$1+$e

$2+$e

$3+$e

$4+$e

$5+$e

$6+$e

$7+$e

$8+$e

$9+$e

$10+$e

$11+$e

$12+$e

$3.$ Suppose P$1,$ P$2,$ P$3,$ P$4$ are in this order in the Ready Queue, and that the following sequence of events occurs:

Time $10$: P$1$ invokes write

Time $15$: P$2$ invokes write

Time $25$: P$3$ invokes read

Time $30$: Interrupt $($P$1\text{'}$s write complete$)$ Time $40$: Interrupt $($P$3$s read complete$)$ Time $45$: P$4$ terminates

Time $50$: P$1$ terminates

There is no no$$on of a $$me slice and a process yields to another process only when it invokes an I$/$O opera$$on $($read$/$write$)$ or terminates.

Time

Running

Ready

Blocked

$0+$e

$10+$e

$15+$e

$25+$e

$30+$e

$35+$e

$40+$e

$45+$e

$50+$e

$4.$ A$)$ Explain the fork func$$on and the return values for the fork func$$on$.$ B$)$ What is the output of the following code:

intx$=5$;

int main$()\{$

pid$\_$t ret;

ret $=$ fork$()$; if$($ret$!=0)\{$

prin$("$parent: x $=\%$d

$",$ x $-4)$; $\}$

else $\{$

prin$("$child: x $=\%$d

$",$ x $+4)$;

$\}\}$

Note: Explaining your thought process will get you par$$al credit in case the answer is incorrect.

$5.$ Draw a process tree for the following code: void parent$\_$child$\_$fork$()$

$\{$

prin$("$L$0$

$")$; fork$()$; prin$("$L$1$

$")$; fork$()$; prin$("$L$2$

$")$; fork$()$; prin$("$Bye

$")$;

$\}$