Thanks for the reply.

i have just started programming on microcontorllers and i have done some programming on 89s52 in assembly language with 8 leds like

LED flash @1hz using mov, acall and sjmp
LED swap @1hz using swap
LED rotate left right using rl and rr
LED diverse, converse and diverseconverse using rr,rl,anl and djnz

now i want to make a sand glass using 8leds

in sand glass one led will start running and at the end (at 8th position) it will stop in on condition and become in latch.

then again one led will start running and it will stop at 7th position and become in latch

then 6th, 5th ....1st

finaly all 8 leds will on

sand dropping cycle will finished

now in next cycle 1st led will goes off then 2nd then 3rd.....8th

and finaly all leds will goes off

i want to meke this progamme using logical operation like using anl,orl.

please give me some idea to make this logic.

thanks in advance
santosh kumar