FM_STEFRMA0
stu &= ~ (FM_STECFRMA0 | FM_STEFRMA0 | FM_STEFRMS) ;
if (stu & (FM_STEFRMA0 | /* end of asyn tx */
outpw(FM_A(FM_IMSK1U),~(imask|FM_STEFRMA0)) ;
outpw(FM_A(FM_IMSK1U),~(imask&~FM_STEFRMA0)) ;