SND_BRK
set_bits |= SND_BRK;
clear_bits |= SND_BRK;
up->curregs[R5] &= ~SND_BRK;
set_bits |= SND_BRK;
clear_bits |= SND_BRK;
uap->curregs[R5] &= ~SND_BRK;
set_bits |= SND_BRK;
clear_bits |= SND_BRK;
up->curregs[R5] &= ~SND_BRK;
zport->regs[5] |= SND_BRK;
zport->regs[5] &= ~SND_BRK;