In this section we are going to:

- Review how to set (1), clear (0), or toggle (0/1) all bits in a Port

- Set a single bit in a port to 1 using OR. OR symbol used is "|"

- Clear a single bit in a port to 0 using AND. AND symbol used is "&"

- Toggle a single bin in a port using NOT

- "Bit Manip: OR with 1 to set, AND with 0 to clear."

OR Gate

Examine the Truth Table on the right: when A or B is a 1, there is a 1 OUTput at Q in the OR Logic Gate on the left.

OR symbol is "|".

OR a bit with 0: the bit (0 or 1) remains the same.

OR a bit with 1: the bit (0 or 1) becomes a 1. This is how we set a bit.

AND Gate

Examine the Truth Table on the right: when both A and B are a 1, there is a 1 OUTput at Q in the OR Logic Gate on the left.

AND symbol is "&".

AND a bit with 1: the bit (0 or 1) remains the same.

AND a bit with 0: the bit becomes a 0. This is how we clear a bit.

NOT Gate

Examine the Truth Table on the right: if A is 1 then OUTput is 0. If A is 0, then OUTput is 1. Also known as an inverter gate.

NOT symbol is "~".

NOT a port of 8 bits: 0000 0001 becomes 1111 1110. 0x01 becomes 0xFE.

NOT is used to toggle a bit.

Examine the Truth Table on the right: if either A or B but not both is a 1, then OUTput is 1.

EXOR symbol is "^"

EXOR a 0 or 1 bit with 0: the Port bit remains the same.

EXOR a 1 bit with 1: the Port bit becomes a 0.

EXORing any bit with a 1 will toggle it (0 becomes 1, 1 becomes 0).

In hardware design, the X-OR gate can be used to merge clock and data together into a single datastream.