Hi Bert,
Again, thanks for the reponse.
Does your estimated 28.125 MSec include the serial transmission to the LCD? If so what about without it, as it is only temporary to see what I'm getting. I am turning the wheel very, very slowly, just to see interrupts the intflag values.
Below is a table of the results for one revolution I am getting. The last column is the elapsed minutes.

Int # Int1Flg Int0Flg Int2Flg Count(A) Count(R) Count(B) Seconds
1 1 0 0 1 0 0 31
2 1 1 1 1 0 0 63
3 1 1 1 1 0 0 78
4 1 0 0 2 0 0 96
5 1 1 1 2 0 0 128
6 1 1 1 2 2 2 139
7 1 0 0 3 0 0 154
8 1 1 1 3 0 0 165
9 1 1 1 3 0 0 176
10 1 1 0 3 0 0 189
11 1 1 1 3 0 0 204
12 1 1 1 3 0 0 211

I plan to change timer0 to give me 10 or 100 counts per second, in order to get a more precise time with which to calculate rate. Should that work?
Forgive me if I plead ignorance of the DT_INT, can you enlighten me?
regards
Tom