diff --git a/consts.c b/consts.c
index 4a9d776..fe01ea4 100644
--- a/consts.c
+++ b/consts.c
@@ -1,6 +1,6 @@
 #ifndef CONSTS
 #define CONSTS
-#define VERSION 3
+#define VERSION 4
 
 #endif /* ifndef CONSTS
 #define CONSTS
diff --git a/instruktion.c b/instruktion.c
index 7c30044..015d2c4 100644
--- a/instruktion.c
+++ b/instruktion.c
@@ -31,5 +31,8 @@
 #define JMP 23
 #define BRF 24
 #define BRT 25
+#define CALL 26
+#define RET 27
+#define DROP 28
 
 #endif /* ifndef INSREUKTION */
diff --git a/njvm.c b/njvm.c
index 4daa57c..f642d31 100644
--- a/njvm.c
+++ b/njvm.c
@@ -11,7 +11,7 @@
 struct program *program;
 
 // SDA
-unsigned fp;
+int fp;
 int debug = 0;
 
 void version(void) {
@@ -26,16 +26,28 @@ void execute(struct program *program, struct sda *sda) {
     struct stack stack;
     stack.size = 1000;
     stack.currentFrame = 0;
+    struct stack callStack;
+    callStack.size = 1000;
+    callStack.currentFrame = 0;
 
     for (int i = 0; i < stack.size; ++i) {
         struct stackFrame *frame = malloc(sizeof(struct stackFrame));
-        frame->fp = malloc(sizeof(unsigned int) * stack.size);
-        frame->sp = malloc(sizeof(unsigned int) * stack.size);
+        frame->fp = malloc(sizeof(int) * stack.size);
+        frame->sp = malloc(sizeof(int) * stack.size);
         frame->bp = NULL;
         stack.frames[i] = frame;
     }
 
+    for (int i = 0; i < callStack.size; ++i) {
+        struct stackFrame *frame = malloc(sizeof(struct stackFrame));
+        frame->fp = malloc(sizeof(int) * stack.size);
+        frame->sp = malloc(sizeof(int) * stack.size);
+        frame->bp = NULL;
+        callStack.frames[i] = frame;
+    }
+
     struct stackFrame *currentFrame = NULL;
+    //struct stackFrame *currentCallFrame = NULL;
     unsigned int tmp;
     int intInput;
     char charInput;
@@ -130,7 +142,9 @@ void execute(struct program *program, struct sda *sda) {
             case PUSHL:
                 if (debug == 1) printf("PUSHL %d\n", SIGN_EXTEND(IMMEDIATE(instruction)));
                 currentFrame = stack.frames[stack.currentFrame];
-                push(&stack, currentFrame->fp[SIGN_EXTEND(IMMEDIATE(instruction))]);
+                currentFrame->bp = currentFrame->sp;
+                int x = SIGN_EXTEND(IMMEDIATE(instruction));
+                push(&stack, currentFrame->fp[x]);
                 break;
             case POPL:
                 if (debug == 1) printf("POPL %d\n", SIGN_EXTEND(IMMEDIATE(instruction)));
@@ -224,6 +238,31 @@ void execute(struct program *program, struct sda *sda) {
                     i = j;
                 }
                 break;
+            case CALL:
+                tmp = SIGN_EXTEND(IMMEDIATE(program->program[i]));
+                if (j-- >= program->size) {
+                    printf("Error: Call out of program memory\n");
+                    goto end;
+                }
+                push(&callStack, i + 1);
+                i = tmp;
+                break;
+            case RET:
+                if (debug == 1) printf("RET\n");
+                tmp = pop(&callStack);
+                if (tmp-- >= program->size) {
+                    printf("Error: Return out of program memory\n");
+                    goto end;
+                }
+                i = tmp;
+                break;
+            case DROP:
+                tmp = SIGN_EXTEND(IMMEDIATE(instruction));
+                if (debug == 1) printf("DROP %d\n", tmp);
+                for (int b = 0; b < tmp; ++b) {
+                    pop(&stack);
+                }
+                break;
         }
     }
 
diff --git a/program.c b/program.c
index b2a8dd9..e7b35ea 100644
--- a/program.c
+++ b/program.c
@@ -99,6 +99,15 @@ void printProgram(struct program *program) {
             case BRT:
                 strcpy(c,"brt");
                 break;
+            case CALL:
+                strcpy(c,"call");
+                break;
+            case RET:
+                strcpy(c,"ret");
+                break;
+            case DROP:
+                strcpy(c,"drop");
+                break;
             default:
                 strcpy(c, "ERROR");
                 break;
diff --git a/programs/prog5.asm b/programs/prog5.asm
new file mode 100644
index 0000000..6d40f30
--- /dev/null
+++ b/programs/prog5.asm
@@ -0,0 +1,35 @@
+//
+// prog01.asm -- call/ret without args, and without ret value
+//
+
+	asf	3
+	pushc	11
+	wrint
+	pushc	'\n'
+	wrchr
+	call	proc
+	pushc	44
+	wrint
+	pushc	'\n'
+	wrchr
+	rsf
+	halt
+
+proc:
+	asf	2
+	pushc	22
+	wrint
+	pushc	'\n'
+	wrchr
+	call	proctwo
+	rsf
+	ret
+
+proctwo:
+	asf	2
+	pushc	33
+	wrint
+	pushc	'\n'
+	wrchr
+	rsf
+	ret
diff --git a/programs/prog5.bin b/programs/prog5.bin
new file mode 100644
index 0000000..e315107
Binary files /dev/null and b/programs/prog5.bin differ
diff --git a/programs/prog6.asm b/programs/prog6.asm
new file mode 100644
index 0000000..eb3b037
--- /dev/null
+++ b/programs/prog6.asm
@@ -0,0 +1,28 @@
+//
+// prog02.asm -- call/ret with args, but without ret value
+//
+
+	asf	3
+	pushc	11
+	pushc	33
+	call	proc
+	drop	2
+	rsf
+	halt
+
+proc:
+	asf	2
+	pushl	-4
+	wrint
+	pushc	'\n'
+	wrchr
+	pushc	22
+	wrint
+	pushc	'\n'
+	wrchr
+	pushl	-3
+	wrint
+	pushc	'\n'
+	wrchr
+	rsf
+	ret
diff --git a/programs/prog6.bin b/programs/prog6.bin
new file mode 100644
index 0000000..d7abab7
Binary files /dev/null and b/programs/prog6.bin differ
diff --git a/stack.c b/stack.c
index 4eb2c26..88b1904 100755
--- a/stack.c
+++ b/stack.c
@@ -10,9 +10,9 @@
 #include <stdlib.h>
 
 struct stackFrame {
-    unsigned int *fp; // Frame pointer
-    unsigned int *sp; // Stack pointer
-    unsigned int *bp; // Base pointer
+    int *fp; // Frame pointer
+    int *sp; // Stack pointer
+    int *bp; // Base pointer
 };
 
 struct stack {
@@ -28,14 +28,16 @@ void printStack(struct stack *stack) {
     }
 }
 
-void push(struct stack *stack, int value) {
+void push(struct stack *stack, unsigned int value) {
     struct stackFrame *currentFrame = stack->frames[stack->currentFrame];
-    *currentFrame->sp++ = value;
+    *(currentFrame->sp) = value;
+    currentFrame->sp++;
 }
 
 int pop(struct stack *stack) {
     struct stackFrame *currentFrame = stack->frames[stack->currentFrame];
-    return *--currentFrame->sp;
+    currentFrame->sp--;
+    return *(currentFrame->sp);
 }
 
 int peek(struct stack *stack, int steps) { // peek is pop without removing the value