diff --git a/part12-wgt/boot/boot.S b/part12-wgt/boot/boot.S
index b68fcd6..73ff435 100644
--- a/part12-wgt/boot/boot.S
+++ b/part12-wgt/boot/boot.S
@@ -1,3 +1,5 @@
+#include "sysregs.h"
+
 #define LOCAL_CONTROL   0xff800000
 #define LOCAL_PRESCALER 0xff800008
 #define OSC_FREQ        54000000
@@ -40,10 +42,23 @@ _start:
     br      x4
     b       1b
 2:  // We're on the main core!
+    ldr     x0, =SCTLR_VALUE_MMU_DISABLED
+    msr	    sctlr_el1, x0		
 
-    // Set stack to start somewhere safe
-    mov     sp, #MAIN_STACK
+    ldr     x0, =HCR_VALUE
+    msr     hcr_el2, x0
 
+    ldr     x0, =SCR_VALUE
+    msr     scr_el3, x0
+
+    ldr     x0, =SPSR_VALUE
+    msr     spsr_el3, x0
+    
+    adr     x0, el1_entry		
+    msr     elr_el3, x0
+
+    eret			
+el1_entry:
     // Clean the BSS section
     ldr     x1, =__bss_start     // Start address
     ldr     w2, =__bss_size      // Size of the section
@@ -52,6 +67,9 @@ _start:
     sub     w2, w2, #1
     cbnz    w2, 3b               // Loop if non-zero
 
+    // Set stack to start somewhere safe
+    mov     sp, #MAIN_STACK
+
     // Jump to our main() routine in C (make sure it doesn't return)
 4:  bl      main
     // In case it does return, halt the master core too
@@ -78,3 +96,9 @@ spin_cpu2:
 .globl spin_cpu3
 spin_cpu3:
         .quad 0
+
+.globl get_el
+get_el:
+	mrs x0, CurrentEL
+	lsr x0, x0, #2
+	ret
diff --git a/part12-wgt/boot/sysregs.h b/part12-wgt/boot/sysregs.h
new file mode 100644
index 0000000..385cd79
--- /dev/null
+++ b/part12-wgt/boot/sysregs.h
@@ -0,0 +1,44 @@
+#ifndef _SYSREGS_H
+#define _SYSREGS_H
+
+// ***************************************
+// SCTLR_EL1, System Control Register (EL1), Page 2654 of AArch64-Reference-Manual.
+// ***************************************
+
+#define SCTLR_RESERVED                  (3 << 28) | (3 << 22) | (1 << 20) | (1 << 11)
+#define SCTLR_EE_LITTLE_ENDIAN          (0 << 25)
+#define SCTLR_EOE_LITTLE_ENDIAN         (0 << 24)
+#define SCTLR_I_CACHE_DISABLED          (0 << 12)
+#define SCTLR_D_CACHE_DISABLED          (0 << 2)
+#define SCTLR_I_CACHE_ENABLED           (1 << 12)
+#define SCTLR_D_CACHE_ENABLED           (1 << 2)
+#define SCTLR_MMU_DISABLED              (0 << 0)
+#define SCTLR_MMU_ENABLED               (1 << 0)
+
+#define SCTLR_VALUE_MMU_DISABLED	(SCTLR_RESERVED | SCTLR_EE_LITTLE_ENDIAN | SCTLR_I_CACHE_ENABLED | SCTLR_D_CACHE_ENABLED | SCTLR_MMU_DISABLED)
+
+// ***************************************
+// HCR_EL2, Hypervisor Configuration Register (EL2), Page 2487 of AArch64-Reference-Manual.
+// ***************************************
+
+#define HCR_RW	    			(1 << 31)
+#define HCR_VALUE			HCR_RW
+
+// ***************************************
+// SCR_EL3, Secure Configuration Register (EL3), Page 2648 of AArch64-Reference-Manual.
+// ***************************************
+
+#define SCR_RESERVED	    		(3 << 4)
+#define SCR_RW				(1 << 10)
+#define SCR_NS				(1 << 0)
+#define SCR_VALUE	    	    	(SCR_RESERVED | SCR_RW | SCR_NS)
+
+// ***************************************
+// SPSR_EL3, Saved Program Status Register (EL3) Page 389 of AArch64-Reference-Manual.
+// ***************************************
+
+#define SPSR_MASK_ALL 			(7 << 6)
+#define SPSR_EL1h			(5 << 0)
+#define SPSR_VALUE			(SPSR_MASK_ALL | SPSR_EL1h)
+
+#endif
diff --git a/part12-wgt/examples/wgt03.c b/part12-wgt/examples/wgt03.c
index 53b4904..8bbecbc 100644
--- a/part12-wgt/examples/wgt03.c
+++ b/part12-wgt/examples/wgt03.c
@@ -1,4 +1,6 @@
 #include "wgt.h"
+#include "include/mem.h"
+#include "include/mb.h"
 
 // ######## REQUIRED FUNCTIONS ########
 
@@ -57,6 +59,8 @@ int clearcount;           /* Counts the number of screen clears. */
 int curx = 0;
 int cury = 0;
 
+extern int get_el(void);
+
 void debugstr(char *str) {
     if (curx + (strlen(str) * 8)  >= 1920) {
        curx = 0; cury += 8;
@@ -96,6 +100,64 @@ void debughex(unsigned int d) {
     debugstr(" ");
 }
 
+int get_max_clock()
+{
+    mbox[0] = 8*4; // Length of message in bytes
+    mbox[1] = MBOX_REQUEST;
+    mbox[2] = MBOX_TAG_GETCLKMAXM; // Tag identifier
+    mbox[3] = 8; // Value size in bytes
+    mbox[4] = 0; // Value size in bytes
+    mbox[5] = 0x3; // Value
+    mbox[6] = 0; // Rate
+    mbox[7] = MBOX_TAG_LAST;
+
+    if (mbox_call(MBOX_CH_PROP)) {
+        if (mbox[5] == 0x3) {
+           return mbox[6];
+        }
+    }
+    return 0;
+}
+
+int get_clock_rate()
+{
+    mbox[0] = 8*4; // Length of message in bytes
+    mbox[1] = MBOX_REQUEST;
+    mbox[2] = MBOX_TAG_GETCLKRATE; // Tag identifier
+    mbox[3] = 8; // Value size in bytes
+    mbox[4] = 0; // Value size in bytes
+    mbox[5] = 0x3; // Value
+    mbox[6] = 0; // Rate
+    mbox[7] = MBOX_TAG_LAST;
+
+    if (mbox_call(MBOX_CH_PROP)) {
+        if (mbox[5] == 0x3) {
+           return mbox[6];
+        }
+    }
+    return 0;
+}
+
+int set_clock_rate(unsigned int rate)
+{
+    mbox[0] = 9*4;  // Length of message in bytes
+    mbox[1] = MBOX_REQUEST;
+    mbox[2] = MBOX_TAG_SETCLKRATE; // Tag identifier
+    mbox[3] = 12;   // Value size in bytes
+    mbox[4] = 0;    // Value size in bytes
+    mbox[5] = 0x3;  // Value
+    mbox[6] = rate; // Rate
+    mbox[7] = 0;    // Rate
+    mbox[8] = MBOX_TAG_LAST;
+
+    if (mbox_call(MBOX_CH_PROP)) {
+        if (mbox[5] == 0x3 && mbox[6] == rate) {
+           return 1;
+        }
+    }
+    return 0;
+}
+
 void timer_routine (void)
 {
   timer++;
@@ -103,13 +165,20 @@ void timer_routine (void)
 
 void wgt03()
 {
+  mem_init();
   vga256 ();                     /* Initialize WGT system        */
 
   debugstr ("WGT Example #3"); debugcrlf(); debugcrlf(); 
   debugstr ("This program will use the wcls routine to clear the screen"); debugcrlf();
   debugstr ("using random colors as fast as it can until you press a key."); debugcrlf();
   debugstr ("It will then report the highest frame rate possible on your computer."); debugcrlf(); debugcrlf(); debugcrlf();
-  debugstr ("Press any key to continue."); debugcrlf();
+
+  int el = get_el();
+  debugstr("Exception level: "); debughex(el); debugcrlf();
+  int setter = set_clock_rate(get_max_clock());
+  debugstr("Set clock returned "); debughex(setter); debugcrlf(); debugcrlf(); debugcrlf();
+
+  debugstr ("Press any key to continue.");
   getch ();
 
   clearcount = 0;
@@ -134,10 +203,17 @@ void wgt03()
 
   wcls(vgapal[0]);
 
+  int clock = get_clock_rate();
+  debugstr("Clock rate: "); debughex(clock); debugcrlf();
+
+  int maxclock = get_max_clock();
+  debugstr("Max clock rate: "); debughex(maxclock); debugcrlf();
+
   unsigned int fps = clearcount / (timer / TIMERSPEED);
-  debughex(fps); debugstr("frames per second"); debugcrlf();
+  debughex(fps); debugstr("frames per second"); debugcrlf(); debugcrlf(); debugcrlf();
+
   debugstr ("This is the highest frame rate your computer can produce for full screen\n"); debugcrlf();
-  debugstr ("animation."); debugcrlf();
+  debugstr ("animation.");
 }
 
 void main()
diff --git a/part12-wgt/include/mb.h b/part12-wgt/include/mb.h
index 0e1861b..d2c1d16 100644
--- a/part12-wgt/include/mb.h
+++ b/part12-wgt/include/mb.h
@@ -1,3 +1,5 @@
+#pragma once
+
 extern volatile unsigned int mbox[36];
 
 enum {
@@ -18,6 +20,9 @@ enum {
 
 enum {
     MBOX_TAG_SETPOWER   = 0x28001,
+
+    MBOX_TAG_GETCLKRATE = 0x30002,
+    MBOX_TAG_GETCLKMAXM = 0x30004,
     MBOX_TAG_SETCLKRATE = 0x38002,
 
     MBOX_TAG_SETPHYWH   = 0x48003,
diff --git a/part12-wgt/lib/mem.c b/part12-wgt/lib/mem.c
index 4e772db..bb30414 100644
--- a/part12-wgt/lib/mem.c
+++ b/part12-wgt/lib/mem.c
@@ -2,8 +2,9 @@ extern unsigned char _end[];
 
 // Define the heap
 
-unsigned char *HEAP_START = &_end[0];
-unsigned int   HEAP_SIZE  = 0x30000000; // Max heap size is 768Mb
+// unsigned char *HEAP_START = &_end[0]; // End of kernel
+unsigned char *HEAP_START = (unsigned char *)0x400000; // Top of stack
+unsigned int   HEAP_SIZE  = 0x30000000; // Max heap size is 764Mb
 unsigned char *HEAP_END;
 
 // Set up some globals