Bit addressability means a single bit alone in a register can be accessed. Let us consider the example of 8051 which has the P0, P1, P2, P3 I/O banks.

Here, P0.0,P0.1,P0.2,...P0.7 like that each pin can be accessed. P0 stands for Port and .x(0 to 7) stands for pin number.

Some of the 8051 compiler like keil P0^0 denotes as P0.0.

Here, P0.0,P0.1,P0.2,...P0.7 like that each pin can be accessed. P0 stands for Port and .x(0 to 7) stands for pin number.

Some of the 8051 compiler like keil P0^0 denotes as P0.0.