FD_SET           1977 src/dps8/dps8_mgp.c       FD_SET(status_conns[0], &rfd);
FD_SET           1987 src/dps8/dps8_mgp.c           FD_SET(mgp_dev_state.conns[i].skt, &rfd);
FD_SET           1064 src/simh/sim_sock.c FD_SET (sock, rw_p);
FD_SET           1065 src/simh/sim_sock.c FD_SET (sock, er_p);