Design Example: Inputs, Outputs and States

? Example:

Consider the student association coffee vending machine which sells coffee at 15¢/cup. The machine will accept nickles, dimes, and quarters, one at a time. The coffee release line will be set to true when 15¢ or more has been put into the machine and the machine will return the correct change.

M1 = ( ?1, Q1, Z1, ?1, ?1?)

Sequential

Machine

Present

State

Q1 = { q0¢, q5¢, q10¢ }

Input

?1 = { 5¢, 10¢, 25¢ }

Output

Z1 = { D0¢, R0¢, R5¢,

R10¢, R15¢, R20¢ }

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