Task Description

For this assignment, you are required to implement a simple simulation of a

snack$/$vending machine.

L$/$T $01234567$

$0$

$1$

$2$

$3$

$4$

$5$

$6$

$7$

The snack machine is a $8$x$8$ grid where the left to right diagonal is reserved for

the claw to retrieve snacks. Snacks are selected by inputting a top $($T$)$ and left

$($L$)$ number. Snacks that are missing are tagged with an $$X$.$

The snack machine has two inputs:

$$ Input $1($T$)$ represents the Top number $(0-7).$

$$ Input $2($L$)$ represents the Left number $(0-7).$

Requirements:

The snack machine can only vend where there are snacks $($across locations $1,$

$3,6,$ and $7).$ Snack slots $2,4$ and $5$ are currently empty and the venting machine

will not work if these locations are selected. The snack machine will vend if L $=$

$0,1,3,6,$ or $7,$ T $=0,1,3,6,$ or $7,$ and L $!=$ T$.$ Any other combination of L and T

values will result in a vending error and no snack will be vended.

Example $1$: If Left $($L$)$ is $1$ and the Top is $(7),$ the snack at $(1,7)$ is

successfully vended.

$3$

Example $2$: The Left $($L$)$ is $2$ and the Top $($T$)$ is $4.$ However, there is no

snack at $(2,4)$ and there is a vending error. No snack was released.

Note: These are just a few examples. There are $($many$)$ more cases that

result in successful or unsuccessful snack vending. Your circuit must

correctly show a successful or unsuccessful vending for each possible

case.

For this assignment, the Left number $($L$)$ will be represented by three inputs $(3$

bits$).$ The three L inputs are named as L$1,$ L$2,$ and L$3.$ The table below shows

the assignment of bits to each L value for L$1,$ L$2,$ and L$3.$

For this assignment, Top number $($T$)$ will be represented by three inputs $(3$ bits$).$

The three T inputs are named as T$1,$ T$2,$ and T$3.$ The table below shows the

assignment of bits to each T value for T$1,$ T$2,$ and T$3.$

L and T Inputs

Part A:

The implementation for this part must use only the three basic logic gates

$($AND$,$ OR$,$ NOT$).$

$$ Each AND gate and each OR gate can have only $2$ inputs.

$$ Each NOT gate can have only $1$ input.

$$ No other logic gates or circuits are permitted to be used in your circuit

for Part A$.$

You are required to implement a circuit where the user $($you$)$ can input a value

for the Left number $($L$)$ using value $($L$1,$ L$2,$ and L$3)$ and a Top number $($T$)$ using

value $($T$1,$ T$2,$ and T$3).$

The circuit decodes the L$1,$ L$2,$ L$3$ and T$1,$ T$2,$ T$3$ values using a decoder $($see

lecture notes$)$ made up of only the permitted logic gates to determine if the

requirements for vending a snack are met $($see the requirements section on

page $2).$

The output is via a single output pin $($green circle in Logisim$)$:

L value L$1$ L$2$ L$3$

$0000$

$1001$

$2010$

$3011$

$4100$

$5101$

$6110$

$7111$

T value T$1$ T$2$ T$3$

$0000$

$1001$

$2010$

$3011$

$4100$

$5101$

$6110$

$7111$

$4$

The output pin must be labelled Successful which is lit if L $=0,1,3,6,$ or $7,$ T

$=0,1,3,6,$ or $7,$ and L $!=$ T$.$ The output pin is not lit for any other combination

values of L and T$.$ Task DescrintionTask Descrintion