b@0: function pairKey
b@0: 
b@0: hf=gcf;
b@0: c=get(hf,'currentcharacter');
b@0: switch c
b@0: case '4' % left play A
b@0:    PCpush(hf,1);
b@0: case '6'	% right play B
b@0:    PCpush(hf,3);
b@0: case ' ' % space stop   
b@0:    PCpush(hf,2);
b@0: end