When you code up your delay routine you need to make sure to add the number of NOP instructions inside the loops that correspond to the numbers in $D$7 -> $D$9 of the spreadsheet. Also enter the frequency in Hz into $C$5. If you have a standard type 8051 with the instruction at XTAL/12 then you put the 12 in cell $F$5. If another higher performance part with different divider like 6 or 4 or 3 or 1 then enter that into $F$5 instead.

It is a good idea to fiddle with the values N and the three "nop" counts with an entry A value of 1 so that the delay is as close as possible to the delay resolution you desire. For example, if you wanted 1 msec resolution then if the values are picked corectly then the value in A when you call the subroutine is the number of milliseconds of delay (for up to 255 milliseconds since A is a byte value on the 8051). For the 1 msec exanple I set the spreadsheet to:
Freq=12000000
Divider=12
InnerNOP=7
OuterNOP=1
OnceNOP=0
N=110
Entry A=1
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This gives delay == 1 millisecond (1/1000 th second).

Michael