int8_t *insnBuffer;
        /* output buffer for single DA outputs */
        int16_t *outBuffer;
-       /* is it USB_SPEED_HIGH or not? */
-       short int high_speed;
-       /* asynchronous command is running */
-       short int ai_cmd_running;
-       short int ao_cmd_running;
-       /* pwm is running */
-       short int pwm_cmd_running;
-       /* continuous acquisition */
-       short int ai_continuous;
-       short int ao_continuous;
+
+       unsigned high_speed:1;
+       unsigned ai_cmd_running:1;
+       unsigned ai_continuous:1;
+       unsigned ao_cmd_running:1;
+       unsigned ao_continuous:1;
+       unsigned pwm_cmd_running:1;
+
        /* number of samples to acquire */
        int ai_sample_count;
        int ao_sample_count;