RBX_DUAL
OPT_SET(RBX_PAUSE) | OPT_SET(RBX_DUAL) | \
opts |= OPT_SET(RBX_DUAL);
if (OPT_CHECK(RBX_DUAL))
RBX_DUAL,
opts |= OPT_SET(RBX_DUAL) |
ioctrl = OPT_CHECK(RBX_DUAL) ? (IO_SERIAL|IO_KEYBOARD) :
RBX_DUAL,
if (OPT_CHECK(RBX_DUAL)) {