public void decb()
    {
       m6809.b = m6809.b-1&0xFF;	
       CLR_NZV();
       SET_FLAGS8D(m6809.b);
       //if(m6809log!=null) fprintf(m6809log,"M6809#%d decb :PC:%d,PPC:%d,A:%d,B:%d,D:%d,DP:%d,U:%d,S:%d,X:%d,Y:%d,CC:%d,EA:%d\n", cpu_getactivecpu(),m6809.pc,m6809.ppc,m6809.a,m6809.b,getDreg(),m6809.dp,m6809.u,m6809.s,m6809.x,m6809.y,m6809.cc,ea);
    }