Hi,

Suppose I have this 1-bit ALU circuit, If I need to add an overflow, should I add it between C in and C out? Eventually, I need to put the 1-bit ALU together to become 4-bit ALU with overflow.
Please Help.

 

I forget how does overflow differ from carry out?

Please give truth table.

Tim S.

 

I forget how does overflow differ from carry out?

Please give truth table.

Tim S.

Or maybe they are the same, the final carry out is overflow, how about the first carry in - in the 4-bit ALU, what it suppose to be?
Thanks,
Danny

 

If there is a carry out, then this is an indication that an overflow has occurred and thus the result is invalid. The carry in is a useful pin that does what it says. It provides a way to insert a carry in an operation. Is there something more to it?

 

If there is a carry out, then this is an indication that an overflow has occurred and thus the result is invalid. The carry in is a useful pin that does what it says. It provides a way to insert a carry in an operation. Is there something more to it?

I was just curious, if I should leave it be or put a constant 0 or 1.

 

You want a constant 0 there. There is no carry in in a fresh, new operation. It would be like wanting to find how much is 1+1 and adding an extra 1 (as carry in) for some reason.

 

You want a constant 0 there. There is no carry in in a fresh, new operation. It would be like wanting to find how much is 1+1 and adding an extra 1 (as carry in) for some reason.

Thanks a lot