Respected Neil and Jan Sir,

I apologies for the shorthands, I'll take care in the near future definately.

Sir I am not getting the concept at all THAT WHAT IS THE DIFFERNCE IN THE COMMON CATHODE AND COMMON ANODE

Have a look to the following code for common anode ... where

P2.0 trough P2.7 is connected to driver transistor, and all eight 7 segment is connected to P0.0 trough P0.6 parallelly. Remember, that all we want to do with this lesson is write multi number ( 1-2-3-4-5-6-7-8 ) to 1st, 2nd, 3rd, 4th, 5th, 6th, 7th and 8th 7 segmen each.

mov P0,#11111001b;write a number '1'
clr P2.7 ;turn on 1st 7 segment
call delay ;call delay time
setb P2.7 ;turn off 1st 7 segment

mov P0,#11011011b;write a number '2'
clr P2.6 ;turn on 2nd 7 segment
call delay ;call delay time
setb P2.6 ;turn off 2nd 7 segment

Sir, Here if we take 1 as the LED high situation then its not

giving our desired DIPLAY NUMBER ie 1 and 2 ... but if we

consider 0 as the LED high point then it works fine ...

But in the book 8051 microcontrollers programming by Kenneth J. Ayala, he has taken common cathode and there too he has considered 0 as the LED high situation ... then where the 1 LED high situation is used ... Is 0 and 1 depend on the common anode and common cathode ... ???

If it is the case then both are using diffrent cases ... but are considering ZERO as the LED HIGH point ...

I think I have cleared my doubt to you ...

I am in need for your kind guidance ...

regards
Arvind Shrivastava ...