3 button mouse is needed for twm? (In English)

[Kenji Okamoto]

This may have been solved already, if so, please forgive my stupid question.

I'm using Intel's SVR4 and ATI's VGA Wonder+/512k card with 2 button 
bus mouse which comes with the card.

When I tried to use twm in X Window x11r3, the second button cannot be 
recognized.  This may demand me to buy a new 3 button bus mouse?
If so, please let me know which kind of mouse can be appricable to this
problem.   I have no more serial ports for mice, so bus mouse is the
neccessary condition.  

thnks in advance,

ken