diff --git a/server/drivers/lcd_sem.c b/server/drivers/lcd_sem.c
index 9b4fe52..642ee84 100644
--- a/server/drivers/lcd_sem.c
+++ b/server/drivers/lcd_sem.c
@@ -1,3 +1,7 @@
+/** \file server/drivers/lcd_sem.c
+ * semaphore code to mediate access to the parallel port.
+ */
+
 /*
  * lcd_sem.c  -- semaphore code written for lcdtime and meter to mediate
  * access to the parallel port.
@@ -34,7 +38,6 @@
 #include "lcd_sem.h"
 
 // according to X/OPEN we have to define it ourselves
-//#ifdef _SEM_SEMUN_UNDEFINED
 #ifndef HAVE_UNION_SEMUN
 union semun {
 	int val;                    /* value for SETVAL */
@@ -53,116 +56,125 @@ union semun {
 #define SEM_WAIT        0,-1,SEM_UNDO
 
 /* functions local to this file */
-static key_t getkey (register char *p);
+static key_t getkey(register char *p);
 
 /* global variables */
 static struct sembuf semaphore_wait = { SEM_WAIT };
 static struct sembuf semaphore_signal = { SEM_SIGNAL };
 
-/*
- * getkey  returns the key for the semaphore
- */
 
+/**
+ * Return the key for the semaphore.
+ */
 static key_t
-getkey (register char *p)
+getkey(register char *p)
 {
-	return ((key_t) SEMKEY);
+	return((key_t) SEMKEY);
 }
 
-/*
- * create the semaphore if one doesn't exist and initialise it to 1, else 
- * return the semaphore set id
+
+/**
+ * Get semaphore.
+ * If the semaphore does not exist, create it and initialise it to 1, 
+ * otherwise simply return the semaphore ID.
+ * \return     Semaphore ID on success; terminate program with code \c 1 on error.
  */
 
 int
-sem_get (void)
+sem_get(void)
 {
 	int semid;
 	union semun semval;
 
-	if ((semid = semget (getkey (SEMAPHORE), SEMCOUNT, IPC_CREAT | IPC_EXCL | WMODE)) < 0) {
+	if ((semid = semget(getkey(SEMAPHORE), SEMCOUNT, IPC_CREAT | IPC_EXCL | WMODE)) < 0) {
 		switch (errno) {
 		case EEXIST:
 			/* semaphore set exists, get id and return it */
-			if ((semid = semget (getkey (SEMAPHORE), SEMCOUNT, IPC_EXCL | WMODE)) < 0) {
-				perror ("semget");
-				exit (1);
+			if ((semid = semget(getkey(SEMAPHORE), SEMCOUNT, IPC_EXCL | WMODE)) < 0) {
+				perror("semget");
+				exit(1);
 			}
 			return semid;
 			break;
 		case EACCES:
 			/* don't have permissions for semaphore, need to change key */
-			perror ("semget, can't get permissions for semaphore");
-			exit (1);
+			perror("semget, can't get permissions for semaphore");
+			exit(1);
 			break;
 		default:
-			perror ("semget");
-			exit (1);
+			perror("semget");
+			exit(1);
 			break;
 		}
 	} else {
 		/* initialise semaphore to 1 */
 		semval.val = 1;
 
-		if (semctl (semid, 0, SETVAL, semval) < 0) {
-			perror ("setval, can't initialise semaphore");
-			exit (1);
+		if (semctl(semid, 0, SETVAL, semval) < 0) {
+			perror("setval, can't initialise semaphore");
+			exit(1);
 		}
 	}
 
 	return semid;
 }
 
-/*
- * wait on the semaphore
- */
 
+/**
+ * Wait on the semaphore.
+ * \param sid  Semaphore ID.
+ * \return     \c 0 on success; terminate program with code \c 1 on error.
+ */
 int
-sem_wait (int sid)
+sem_wait(int sid)
 {
-	if (semop (sid, &semaphore_wait, 1) < -1) {
-		perror (SEMAPHORE);
-		exit (1);
+	if (semop(sid, &semaphore_wait, 1) < -1) {
+		perror(SEMAPHORE);
+		exit(1);
 	}
 
 	return 0;
 }
 
-/*
- * signal on the semaphore
- */
 
+/**
+ * Signal on the semaphore.
+ * \param sid  Semaphore ID.
+ * \return     \c 0 on success; terminate program with code \c 1 on error.
+ */
 int
-sem_signal (int sid)
+sem_signal(int sid)
 {
-	if (semop (sid, &semaphore_signal, 1) < -1) {
-		perror (SEMAPHORE);
-		exit (1);
+	if (semop(sid, &semaphore_signal, 1) < -1) {
+		perror(SEMAPHORE);
+		exit(1);
 	}
 
 	return 0;
 }
 
-/*
- * remove the semaphore
- */
 
+/**
+ * Remove the semaphore
+ * \param sid  Semaphore ID.
+ * \return     \c 0 on success; terminate program with code \c 1 on error.
+ */
 int
-sem_remove (int sid)
+sem_remove(int sid)
 {
 #ifdef EIDRM
 	int i;
 	union semun dummy;
 
-	if ((i = semctl (sid, 0, IPC_RMID, dummy)) < 0) {
+	if ((i = semctl(sid, 0, IPC_RMID, dummy)) < 0) {
 		switch (i) {
 		case EIDRM:
 			/* semaphore removed */
 			return 0;
 			break;
 		default:
-			perror ("semctl, removing semaphore");
-			exit (1);
+			perror("semctl, removing semaphore");
+			exit(1);
 		}
 	}