-#define BITS7 020
-#define BITS8 030
-#define TWOSB 040
-#define PENABLE 0100
-#define OPAR 0200
-#define MSE 040 /* Master Scan Enable */
-#define RIE 0100 /* Receiver Interrupt Enable */
-#define SAE 010000 /* Silo Alarm Enable */
-#define TIE 040000 /* Transmit Interrupt Enable */
-#define DZ_IEN (MSE+RIE+TIE+SAE)
-#define PERROR 010000
-#define FRERROR 020000
-#define OVERRUN 040000
-#define SSPEED 7 /* std speed = 300 baud */
-
-#define dzlpr dzrbuf
-#define dzmsr dzbrk
-#define ON 1
-#define OFF 0
+/*
+ * Registers and bits
+ */
+
+/* bits in dzlpr */
+#define BITS7 0020
+#define BITS8 0030
+#define TWOSB 0040
+#define PENABLE 0100
+#define OPAR 0200
+
+/* bits in dzrbuf */
+#define DZ_PE 010000
+#define DZ_FE 020000
+#define DZ_DO 040000
+
+/* bits in dzcsr */
+#define DZ_32 000001 /* DZ32 mode */
+#define DZ_MIE 000002 /* Modem Interrupt Enable */
+#define DZ_CLR 000020 /* Reset dz */
+#define DZ_MSE 000040 /* Master Scan Enable */
+#define DZ_RIE 000100 /* Receiver Interrupt Enable */
+#define DZ_MSC 004000 /* Modem Status Change */
+#define DZ_SAE 010000 /* Silo Alarm Enable */
+#define DZ_TIE 040000 /* Transmit Interrupt Enable */
+#define DZ_IEN (DZ_32|DZ_MIE|DZ_MSE|DZ_RIE|DZ_TIE|DZ_SAE)
+
+/* flags for modem-control */
+#define DZ_ON DZ_DTR
+#define DZ_OFF 0
+
+/* bits in dzlcs */
+#define DZ_ACK 0100000 /* ACK bit in dzlcs */
+#define DZ_RTS 0010000 /* Request To Send */
+#define DZ_ST 0004000 /* Secondary Transmit */
+#define DZ_BRK 0002000 /* Break */
+#define DZ_DTR 0001000 /* Data Terminal Ready */
+#define DZ_LE 0000400 /* Line Enable */
+#define DZ_DSR 0000200 /* Data Set Ready */
+#define DZ_RI 0000100 /* Ring Indicate */
+#define DZ_CD 0000040 /* Carrier Detect */
+#define DZ_CTS 0000020 /* Clear To Send */
+#define DZ_SR 0000010 /* Secondary Receive */