+ short dzcsr; /* control-status register */
+ short dzrbuf; /* receiver buffer */
+#define dzlpr dzrbuf /* line parameter reg is write of dzrbuf */
+ char dztcr; /* transmit control register */
+ char dzdtr; /* data terminal ready */
+ char dztbuf; /* transmit buffer */
+ char dzbrk; /* break control */
+#define dzmsr dzbrk /* modem status register */