3 files changed, 19 insertions, 19 deletions
diff --git a/comhan.c b/comhan.c
index 73b0c54..febb503 100644
--- a/comhan.c
+++ b/comhan.c
@@ -7,6 +7,7 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <stdlib.h>
 #include "mpx.h"
 
 #define BUF_SIZE 80      /* Size of the command line buffer. */
@@ -79,7 +80,7 @@ void comhan() {
 int get_cmd(char cmd[]){
   /* return the number associated with a command (use STOP, HELP etc) */
 
-  int i =0 ; //loop control
+  int i = 0; //loop control
 
   if (cmd == NULL) {
 	return -1;
diff --git a/main.c b/main.c
index 9bd8b55..c6d567f 100644
--- a/main.c
+++ b/main.c
@@ -12,24 +12,23 @@ pcb * pcb_list;
 pcb * ready_queue;
 pcb * io_init_queue;
 
-int main(void) {
+pcb pcb0;
+pcb pcb1;
+pcb pcb2;
+pcb pcb3;
+pcb pcb4;
+pcb pcb5;
+pcb pcb6;
+pcb pcb7;
+pcb pcb8;
+pcb pcb9;
+pcb pcb10;
+pcb pcb11;
 
+int main(void) {
+	printf("Booting MPX... \n");
 	/* Put initialization code here */
 
-	// allocate memory for PCBs
-	pcb pcb0;
-	pcb pcb1;
-	pcb pcb2;
-	pcb pcb3;
-	pcb pcb4;
-	pcb pcb5;
-	pcb pcb6;
-	pcb pcb7;
-	pcb pcb8;
-	pcb pcb9;
-	pcb pcb10;
-	pcb pcb11;
-
 	// create the chain
 	pcb0.chain  = &pcb1;
 	pcb1.chain  = &pcb2;
@@ -59,8 +58,6 @@ int main(void) {
 
 	pcb_list = &pcb0;
 
-	printf("... booting MPX\n\n");
-
 	comhan();    /* Execute the command handler */
 
 	return 0;
diff --git a/pcb.c b/pcb.c
index 8cffe3f..8f4034a 100644
--- a/pcb.c
+++ b/pcb.c
@@ -146,7 +146,9 @@ int insert_pcb(pcb **queue, pcb * addr, int method) {
 	  current->next = addr;
 	  addr->next = one_after;
 	  addr->prev = current;
-	  one_after->prev = addr;
+	  if (one_after != NULL) {
+		one_after->prev = addr;
+	  }
 	} else {
 
 	  // otherwise, put it at the head