# Multiplier design help

1. Dec 9, 2013

hello,

I'm trying to design a "calculator" that multiplies two four bit binary numbers without using any type of programming or microcontrollers. so far it can multiply and show me the answer, I am using a hex keypad, and ascii display. but I am having trouble since i have to actually show "5x5=25" since x equals 1010 in binary and = equals 1101 in binary. everytime i press those numbers its going to use them to multiply with the number i input before.... Im stuck and frustrated... any help would be nice.

Last edited by a moderator: Dec 9, 2013
2. Dec 9, 2013

### perplexabot

Hello.
I am not so sure how you are implementing this design but why not have it automatically print the "x" sign after you enter the first number and automatically enter "=" after you enter the second number? Is this an option?

3. Dec 9, 2013

is that idk where to send the "1010" value when i press it... thats what i have in my head lol but dont know how to implement

4. Dec 9, 2013

### perplexabot

What do you mean by that? How are you going to implement this design without programming and a microcontroller? Like strait from the keypad to the LCD?

5. Dec 9, 2013

### Staff: Mentor

It sounds like you need to throw an error if the user types anything other than Y x Z =.

If they try to type a 2-digit number like YY x ZZ = just display ERROR or something similar. Or EEEE.

6. Dec 9, 2013

1. The problem statement, all variables and given/known data

ok, so I am designing a basic multiplication calculator using only logic gates registers buffers and ram, and any other chip that doesnt involve programming or microcontrollers. i have the rest of the circuit done all I need is the implementation of a keypad that gives me the output of the number I am pressing in binary(yes i know there is a 3x4 keypad alreade but the profesor wants us to implement it)

3. The attempt at a solution

this is my attempt so far, I have no idea what else to do. maybe someone can help me with this

7. Dec 9, 2013