Need help with the 8051

I am learning to program the 8051.

I have downloaded a simple program I wrote to drive 7 segment display...I need some explenations.

On the microcontroller, the outputs are inverted so that when I wanted a Logic 1, it ouputs a Logic 0 instead, and vice versa.

If I Do

MOV A, #10

that is moving the decimal 10 into the accumulator, which in binary is 00001010

If I then do the following:

MOV P0, A

I am explecting P0.1 and P0.3 to be at Logic 1, but it seems to be the other way round when I download it....

I could easily complement the values in the program, but this is not what I was expecting from what I learnt before.

Any help appreciated...

In case you missed it, and many people do, on most 8051 variants, Port 0 has open collector outputs. This means that a pullup resistor is required for the output to go to a high state.

Thanks for your input! I appreciate it very much. You were right about the pull-up resistors. I have connected those now. But I think they were not the problem.

I think the 8051 was sending the correct values to its pins, but the LEDs on my target board is inverted which was giving me wrong indications. Anyway, I think time will only clear this confusion up as I gain more experience.

Many thanks for your help.