The Dink Network

This is the entire script for dot1 The rest are the same)

void main(void)
{
sp_brain(&current_sprite, 14);
sp_touch_damage(&current_sprite, -1);
&d1 = &current_sprite;
}

void buttonon(void)
{
If (&s1 == 0)
sp_pframe(&current_sprite, 3);
}

void buttonoff(void)
{
If (&s1 == 0)
sp_pframe(&current_sprite, 1)
}

void click(void)
{
If (&s1 == 0)
{
Playsound(17,22050,0,0,0);
sp_pframe(&current_sprite, 3);
&s1 = 1;
external("move", "main");
}
}

void change(void)
{
Playsound(17,22050,0,0,0);
sp_pframe(&d1, 2);
&s1 = 10;
}

I want to make the game x-0(The game where you have a 3x3 board, and one plyer put X, and the other one 0, and you have to fill a line, collumn or diagonal with your sign) using DinkC.

The "change" procedure is called when computer moves.
Another question: how many global variables may I put?(I already have 23, and the program isn't finished yet)