If you don't understand Darrels' EXT explanation, you might want to come back to it at some
point, and re-read it. It can be confusing if you don't get it.

However, what you're trying to do doesn't require you to work in binary. You can just create
a word sized variable, perform whatever math you need to on it, and then load it into Timer1
high & low bytes.

TimerConst VAR WORD

This gives you a 16-bit variable. Now you can do things like TimerConst = 9612. TimerConst
= TimerConst * 5. Now TimerConst = 48060. PBP automatically stores the result for you as
two 8-bit binary values.

Everything is stored as binary since the PIC internal structure is 8-bit registers.

To load TimerConst into Timer1 low & high bytes you use TMR1L = TimerConst.LowByte, and
TMR1H = TimerConst.HighByte.

You can't do something like TMR1H:L=48060 since you're dealing with two 8-bit file registers
for TMR1L and TMR1H. And you're dealing with two 8-bit values for TimerConst.

It takes two separate operations. Load the low byte of TimerConst into TMR1L. Then load
the high byte of TimerConst into TMR1H.