V1[]
Indications are, GPSET in SmileBasic V1 is identical to that in V2.
V2[]
GPSET is a command for setting the colour of a single pixel on the currently selected graphics page.
If the command is given two parameters, x,y, the pixel at coordinates (x,y) is set to the currently selected colour.
If the command is given three parameters, it behaves as above except the third parameter is used for the colour.
V3[]
No information on SmileBasic V3.