slot machine

[matt03]

hi, i'm fairly new to this, so please forgive me with anything i'm doing wrong.

i'm working on a school project. i'm designing a digital slot machine on multisim12.

for the slot machine, i'm using a 0-9 up counter designed with 4 JK flipflops. (3 counters all in all)

the outputs of each flip flop are fed into the input of a BCD to 7-segment decoder then to a 7 segment display.

i wanted my pay out to be the following:

numbers that are not equal = $0

000 - 666 = $20

777 = $999

888 and 999 = $200

however, i am having problems comparing the 3 numbers. right now, i am using nand gates to compare the BCDs of each displayed digit, then the outputs of the nand gates are the inputs of a 2 input nor gate with the other connected to ground. the outputs of the nor gate are then the A inputs of a 4 bit magnitude comparator with the B inputs set at 0111. 

it works at 777, however regardless of whether the numbers are 1-1-1 or 1-2-3, the A less than B output is always $20. 

[Miguel_V]

Hello,

As a school project, I think you'd have more luck posting this in a physics/electronics forum board than here. Because this is not so much about the functionality of Multisim as it is about how to design it. If there is something wrong with your design you can use the measurement probe to measure whether a net is HIGH or LOW to see if your logic is working. Check every wire, designing can be frustrating. If you are 100% sure this should work then we can start taking a look at it.

Kind regards,