Is there a way to send 5 volts to a certain bit in the LPT port without changing the state of the other bits?

Question

I'm using Visual Basic

Answer 1

Just read the present port value and OR in the bit you want to set.

For example we want to set bit 2, and bits 0 & 1 are set:

A=port value ' bit 0 and 1 are set.
B=A OR 4 ' we add in 4 to set bit 2
port value=b ' b=7, bits 0,1,2 are set

To reset bits without affecting others, it's basically the same thing with an AND mask.