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New Member
Hi everyone...Great forum

I need some help designing a circuit tha multilpies two 4-digit numbers using only ic's.If anyone has the schematics up on some site somewhere or has any info pm plz...



New Member
@gene thnx but i asked our lecturer what specifications he wants and he told us the ciruit can be built(and simply to) with ic's only.TO be exact Two shift registers(74LS194), a control unit,a parallel adder,a counter(74Ls161) and thats all about we know...

Stuck in the dark :evil: :evil:


New Member
Sounds like a trick question to me. Why?

Display: Just to display the 4-digit inputs - but especially the product, seems like you will need 8, 7-segment displays. If, for instance the problem was to multiply 9999 times 9999, you would need to display 99,980,001 (thats 8 digits). if you don't display the inputs, how do you know what you keyed-in and if you can't read the output, the project has no value. Setting up the 8 digits and driving them is complex by itself. Maybe the four digit numbers are "0101" and "0110" :D

I don't remember reading anything about power. You know, electricity. To make this thing work, you will need a transformer, bridge, regulator, and filter. Not too bad, but still requires parts that aren't listed by the teacher.

What about a keypad. You know, one of those little things with numbers on it, a "=" key, etc.

What the heck is a "control unit?" Perhaps it is one of those TI special function ICs made for calculating. Maybe we can use a $6 calculator as our "control unit."

Personally, I think there is a trick here and the teacher is on a power/self importance trip. PLEASE post the solution for us.


New Member
@gene Ill deffinetely post the solution when i have it...

As for the power no prob.All we need is a breadboard and a 5v transformer.AS for the control unit, we are supposed to design it using ic's only.To control what???

Personally, I think there is a trick here and the teacher is on a power/self importance trip.
Lol...I think he has lost it completely.Rumour has it he has problems with his wife+ he has more grey hair than my grandmother and he is only 37.To much stress i guess.

Hopefully by friday i will have posted the schematics :wink:


Active Member
Hi hydro,

You dont say that the numbers have to be decimal.
If they can be binary, then multiplication can be
done using shift registers.
And if binary is ok, the display could just be a
row of LEDs.
You will need a key-pad or some system of buttons for
entering the numbers as has already been said.

Power supply could be just a 6v battery.

As you may know, moving a binary display by one
position sideways, performs a multiplication or a
division, depending which way you move it.

I suspect the basis for this exercise is to
demonstrate this.

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