[EMS Discuss] Logic Diagram Challenge

Weston Turner wstnturner at gmail.com
Wed Jan 15 22:04:53 PST 2014


>From a more rigorous or theoretical standpoint, the inverting operations
count as NOT gates. But I guess I didn't say that inverting equals a NOT.
In any case, my four gate solution doesn't use them. I'll represent it here
in Python using four binary bitwise operators, one AND, one OR, and two
XORs.

A and B are anded to make C
A and B are ored  together into the temp variable t
t is xored with B to make D
t is xored with A to make E

The operations are color coded below. Can this be done with fewer
operations?

Python 2.7.3 (default, Nov 11 2012, 18:06:39)
>>> *A, B = 0, 0*
>>> t = A | B; C = A & B; D = B ^ t; E = A ^ t
>>> C, D, E
*(0, 0, 0)*
>>> *A, B = 0, 1*
>>> t = A | B; C = A & B; D = B ^ t; E = A ^ t
>>> C, D, E
*(0, 0, 1)*
>>> *A, B = 1, 0*
>>> t = A | B; C = A & B; D = B ^ t; E = A ^ t
>>> C, D, E
*(0, 1, 0)*
>>> *A, B = 1, 1*
>>> t = A | B; C = A & B; D = B ^ t; E = A ^ t
>>> C, D, E
*(1, 0, 0)*

Cheers,
Weston



On Wed, Jan 15, 2014 at 8:42 PM, Mr. Clif <clif at eugeneweb.com> wrote:

> Sure I can do it in three but two of the gates have to have one inverting
> input each. Since gates often come in quad packs it might be nice to find a
> circuit that would use all four in a pack. Though if it helps my fourth
> gate is just an inverter and there are often left over ones from other
> packages.
>
>     Clif
>
>
>
>
>
> On 01/15/2014 07:42 PM, Weston Turner wrote:
>
>> I'm wondering if anyone can implement this logic table with less than
>> four gates...
>>
>> A B | C D E
>> -------------
>> 0 0 | 0 0 0
>> 0 1 | 0 0 1
>> 1 0 | 0 1 0
>> 1 1 | 1 0 0
>>
>> I figured out a way to implement it with four gates but I'm wondering if
>> it can be reduced further...
>>
>> And if you can only figure out a way to do it with four, then I'm curious
>> to see if you arrived at the same solution I did.
>>
>> Regards,
>> Weston
>> _______________________________________________
>> Discuss mailing list
>> Discuss at eugenemakerspace.com
>> http://eugenemakerspace.com/mailman/listinfo/com.eugenemakerspace.discuss
>>
>
>
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