It will depend on your machine whether or not you can tap.
There is a G84 but it is not true rigid tapping when using the parallel port but it will work if you have spindle control and use a floating holder.
If you have an external motion controller such as CSMIO/IP-A or S or a Kflop, possibly also DSPMC and Galil, then you can do rigid tapping but you have to use a macro to do it.
G94 if feed per min, G95 is feed per rev.
Hood