@MichelJasmin

yes I do use NTP as the starting point of my calculation and I do get the date in the following format...
Thu Jan 01 00:00:00 1970

But your example would (I believe) only work if I happened to check the time on the actual day that the DST or STD time began and only be persistent if I kept track of whether DST or STD was in effect.
However in my case I may power up the clock say on March 12 or any other day of the year and need to determine the current DST/STD status.
I could probably use your example and then check to see if the current date was before or after that date.

@Enigma (Pete)

So how do you translate this bit of code into PICbasic??
DSTStart = (31 - (((5*Year)/4)+ 4) mod 7)
Does MOD 7 mean Y= X // 7 (in your example is MOD the same as the remainder?)

At this point I think I am going to give my code a spin and see how it performs.
but great discussion
Thanks all