The lift $($or$,$ in American English, the 'elevator'$)$ in the Faraday

building only has a maximum capacity of $2$ people. Two sensors

detect people entering $($input ENTER$)$ and exiting $($input EXIT$)$ the

lift. A system is required to implement the following conditions:

If more than $2$ people enter the lift, an alarm $($output ALARM$)$

should sound. Otherwise, the alarm should not sound.

If there are no people in the lift, the lights $($output LIGHTS$)$

should not be turned on$.$ Otherwise, the lights should be

switched on$.$

You should assume that a maximum of one person will enter or

exit the lift during any one clock cycle. You should also assume

that nobody will try to enter the lift once the alarm is sounding.

a$)$ Draw an ASM chart for a synchronous system to provide the

above functionality.

$[8$ marks$]$

b$)$ Using your ASM chart, produce a state transition table for

your design.

$[3$ marks$]$

c$)$ Using your state transition table, produce minimised

Boolean equations for your design.

$[4$ marks$]$