BGE_MBX_IRQ0_LO
bge_writembx_flush(sc, BGE_MBX_IRQ0_LO, 1);
bge_writembx_flush(sc, BGE_MBX_IRQ0_LO, statustag);
bge_writembx_flush(sc, BGE_MBX_IRQ0_LO, 0);