diff --git a/main.cpp b/main.cpp
index e4392fe..c4354eb 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,11 +1,10 @@
 #include <stdlib.h>
 #include <stdio.h>
+#include "vm.h"
 
 int main(int argc, char** argv) {
 
-	int i = 1;
-	char a[4] = { 1, 2, 3, 4 };
-	int x = a[i++] + a[i++];
-	// aci, i == 12 ; x == 21
+	vm_init("test.bin");
+	vm_step();
 	return 0;
 }
\ No newline at end of file
diff --git a/vm.cpp b/vm.cpp
index 488b181..e6025ad 100644
--- a/vm.cpp
+++ b/vm.cpp
@@ -1,4 +1,5 @@
 #include "vm.h"
+#include <stdio.h>
 
 #define MAX_EXTERNAL_CALLS	256
 #define MAX_DATA_STACK		256
@@ -89,29 +90,52 @@ typedef byte(*t_in_port)();
 t_out_port out_ports[256];
 t_in_port in_ports[256];
 
-const unsigned char* vm_program = nullptr;
+unsigned char mem[65536];
+const unsigned char* vm_program = mem;
 int vm_pc = 0;
 int vm_cycles = 0;
 t_stack vm_datastack;
 t_stack vm_callstack;
-unsigned char mem[65536];
 unsigned short rX = 0;
 unsigned char rY = 0;
 unsigned char rZ = 0;
 
 
-void vm_init(const unsigned char* program) {
-	vm_program = program;
+static void load_rom() {
+	FILE *f = fopen("rom.bin", "rb");
+	fseek(f, 0, SEEK_END);
+	long fsize = ftell(f);
+	fseek(f, 0, SEEK_SET);
+	fread(&mem[0x8000], fsize, 1, f);
+	fclose(f);
+}
+
+static void load_program(const char* filename) {
+	FILE *f = fopen(filename, "rb");
+	fseek(f, 0, SEEK_END);
+	long fsize = ftell(f);
+	fseek(f, 0, SEEK_SET);
+	fread(mem, fsize, 1, f);
+	fclose(f);
+}
+
+void vm_init(const char* filename) {
 	vm_pc = rX = rY = rZ = 0;
-	stack_init(vm_datastack, MAX_DATA_STACK);
-	stack_init(vm_callstack, MAX_CALL_STACK);
+	vm_datastack.data = &mem[0x8800];
+	vm_callstack.data = &mem[0x8900];
+	vm_datastack.top = vm_callstack.top = 0;
+	vm_datastack.max = MAX_DATA_STACK;
+	vm_callstack.max = MAX_CALL_STACK;
+	load_rom();
+	load_program(filename);
 }
 
 inline unsigned short WORD() { vm_pc += 2; return vm_program[vm_pc - 2] + (vm_program[vm_pc - 1] << 8); }
 
-void vm_step() {
+const int vm_step() {
 	char val, val2;
 	switch (vm_program[vm_pc++]) {
+
 	case OP_NOP: vm_cycles++; break;
 	case OP_PUSH: stack_push(vm_datastack, vm_program[vm_pc++]); vm_cycles++; break;
 	case OP_POP: stack_pop(vm_datastack); vm_cycles++; break;
@@ -181,6 +205,7 @@ void vm_step() {
 	case OP_IN: stack_push(vm_datastack, in_ports[vm_program[vm_pc++]]()); vm_cycles++; break;
 	case OP_OUT: out_ports[vm_program[vm_pc++]](stack_pop(vm_datastack)); vm_cycles++; break;
 	}
+	return vm_cycles;
 }
 
 void vm_register_call(void(*callback)(t_stack&)) {
@@ -194,3 +219,13 @@ void vm_register_in_port(const byte port, t_in_port callback) {
 void vm_register_out_port(const byte port, t_out_port callback) {
 	out_ports[port] = callback;
 }
+
+void vm_call_interrupt(const char num) {
+	stack_push(vm_callstack, vm_pc);
+	stack_push(vm_callstack, rX & 255);
+	stack_push(vm_callstack, rX >> 8);
+	stack_push(vm_callstack, rY);
+	stack_push(vm_callstack, rZ);
+	vm_pc = num == 0 ? 0xFFFA : 0xFFFD;
+	vm_cycles++;
+}
diff --git a/vm.h b/vm.h
index d402517..8fa2429 100644
--- a/vm.h
+++ b/vm.h
@@ -1,8 +1,10 @@
 #pragma once
 #include "stack.h"
 
-void vm_init(const unsigned char* program);
-void vm_step();
-void vm_register_call(void(*callback)(t_stack&));
+void vm_init(const char* filename);
+const int vm_step();
 void vm_register_in_port(const unsigned char port, unsigned char(*callback)(void));
 void vm_register_out_port(const unsigned char port, void(*callback)(const unsigned char&));
+void vm_call_interrupt(const char num);
+
+void vm_register_call(void(*callback)(t_stack&));