clock_lock       1171 src/dps8/dps8_scu.c static pthread_mutex_t clock_lock = PTHREAD_MUTEX_INITIALIZER;
clock_lock       1178 src/dps8/dps8_scu.c     pthread_mutex_lock (& clock_lock);
clock_lock       1310 src/dps8/dps8_scu.c     pthread_mutex_unlock (& clock_lock);