# Logical Gates

• 08-17-2009, 12:25 AM
lingz89
Logical Gates
Hi, I'm struggling with the topic of logical gates so I hope someone can help me out.
I'm having trouble with the following:
- boolean expressions, De Morgan Law and expressing terms in NOR/NAND only.
- designing circuits
- implementing circuits with given inputs/outputs (4 bit adder?)

An example of the question I'm struggling on would be:

'Write boolean expressions and design a ciruit with three inputs and one output such that the output is 1 if and only if two or more inpurs are 1.'

Help appreciated, I'm finding this topic so confusing.
• 08-17-2009, 01:11 AM
angryboy
little sample:
Code:

```public static boolean andGate(boolean in1, boolean in2){   if(in1 && in2)     return true;   return false; } public static boolean orGate(boolean in1, boolean in2){   if(in1 || in2)     return true;   return false; }```
the int version would be:
Code:

```public static int andGate(int in1, int in2){   if(in1==1 && in2==1)     return 1;   return 0; } public static int orGate(int in1, int in2){   if(in1==1 || in2==1)     return 1;   return 0; }```
Now you would do something similar for NOR/NAND using three inputs.