diff --git a/src/vm/mod.rs b/src/vm/mod.rs
index 16317f2..aebec28 100644
--- a/src/vm/mod.rs
+++ b/src/vm/mod.rs
@@ -1,23 +1,62 @@
 mod module;
 mod op_codes;
 mod util;
+mod platform;
+mod types;
 
 use op_codes::*;
+use platform::PlatformCallFrame;
 use std::alloc::{alloc_zeroed, dealloc, Layout};
+use std::collections::HashMap;
+use types::DmType;
 use util::{get_32_le, get_64_le};
+use crate::vm::module::DmFunction;
+
+pub type PlatformFunction = fn (&mut PlatformCallFrame) -> Result<Option<(u64, DmType)>, String>;
 
 pub struct DmVirtualMachine {
     registers: Vec<u64>,
-    register_types: Vec<RegisterType>,
+    register_types: Vec<DmType>,
+    platform_functions: HashMap<String, PlatformFunction>
 }
 
-struct DmObject {
-    pointer: *mut u8,
+impl DmVirtualMachine {
+    pub fn call(
+        &self,
+        dm_function: &DmFunction,
+        args: Vec<u64>,
+        arg_types: Vec<DmType>
+    ) -> Result<(u64, DmType), String> {
+        run(&dm_function.byte_code, todo!(), todo!());
+        todo!()
+    }
+}
+
+pub struct DmObjectType {
+    name: String,
+    properties: HashMap<String, DmObjectProperty>,
+    fields: HashMap<String, DmObjectField>,
+    methods: HashMap<String, DmFunction>
+}
+
+pub struct DmObject {
+    object_type: Box<DmObjectType>,
+    data: *mut u8,
     size: usize,
     layout: Layout,
 }
 
-pub fn run(code: &Vec<u8>, registers: &mut Vec<u64>, register_types: &mut Vec<RegisterType>) {
+pub struct DmObjectProperty {
+    name: String,
+    property_type: DmType,
+}
+
+pub struct DmObjectField {
+    name: String,
+    field_type: DmType,
+}
+
+pub fn run(code: &Vec<u8>, registers: &mut Vec<u64>, register_types: &mut Vec<DmType>) {
     let mut i = 0;
     while i < code.len() {
         match code[i] {
@@ -25,14 +64,14 @@ pub fn run(code: &Vec<u8>, registers: &mut Vec<u64>, register_types: &mut Vec<Re
                 let target_register = code[i + 1] as usize;
                 let operand = get_32_le!(code, i, 2, u32);
                 registers[target_register] = operand as u64;
-                register_types[target_register] = RegisterType::Int;
+                register_types[target_register] = DmType::Int;
                 i += 6;
             }
             MOV_LONG => {
                 let target_register = code[i + 1] as usize;
                 let operand = get_64_le!(code, i, 2, u64);
                 registers[target_register] = operand;
-                register_types[target_register] = RegisterType::Long;
+                register_types[target_register] = DmType::Long;
                 i += 10;
             }
             MOV_DOUBLE => { /* todo */ }
@@ -49,13 +88,14 @@ pub fn run(code: &Vec<u8>, registers: &mut Vec<u64>, register_types: &mut Vec<Re
                 let layout = Layout::from_size_align(size, 4).unwrap();
                 let pointer = unsafe { alloc_zeroed(layout) };
                 let dm_object = Box::new(DmObject {
-                    pointer,
+                    data: pointer,
                     size,
                     layout,
+                    object_type: todo!()
                 });
                 let dm_object_pointer = Box::into_raw(dm_object) as u64;
                 registers[target_register] = dm_object_pointer;
-                register_types[target_register] = RegisterType::Pointer;
+                register_types[target_register] = DmType::Pointer;
                 i += 6;
             }
             DEALLOC => {
@@ -63,22 +103,22 @@ pub fn run(code: &Vec<u8>, registers: &mut Vec<u64>, register_types: &mut Vec<Re
                 let box_address = registers[target_register];
                 unsafe {
                     let dm_object = Box::from_raw(box_address as *mut DmObject);
-                    dealloc(dm_object.pointer, dm_object.layout);
+                    dealloc(dm_object.data, dm_object.layout);
                 }
                 registers[target_register] = 0;
-                register_types[target_register] = RegisterType::Int;
+                register_types[target_register] = DmType::Int;
                 i += 2;
             }
             MOV_INT_TO => {
                 let target_register = code[i + 1] as usize;
-                if register_types[target_register] != RegisterType::Pointer {
+                if register_types[target_register] != DmType::Pointer {
                     panic!("target_register {} is not a Pointer", target_register);
                 }
                 let offset = get_32_le!(code, i, 2, isize);
                 let box_address = registers[target_register];
                 let new_address = unsafe {
                     let dm_object = Box::from_raw(box_address as *mut DmObject);
-                    let pointer = dm_object.pointer;
+                    let pointer = dm_object.data;
                     pointer.offset(offset).write(code[i + 6]);
                     pointer.offset(offset + 1).write(code[i + 7]);
                     pointer.offset(offset + 2).write(code[i + 8]);
@@ -98,8 +138,8 @@ mod tests {
     use super::*;
     use std::alloc::dealloc;
 
-    fn init_registers(n_registers: usize) -> (Vec<u64>, Vec<RegisterType>) {
-        (vec![0; n_registers], vec![RegisterType::Int; n_registers])
+    fn init_registers(n_registers: usize) -> (Vec<u64>, Vec<DmType>) {
+        (vec![0; n_registers], vec![DmType::Int; n_registers])
     }
 
     #[test]
@@ -145,13 +185,13 @@ mod tests {
         add_alloc(&mut code, 0, 4);
         add_mov_int_to(&mut code, 0, 0, 0xff);
         let mut registers = vec![0; 16];
-        let mut register_types = vec![RegisterType::Int; 16];
+        let mut register_types = vec![DmType::Int; 16];
         run(&code, &mut registers, &mut register_types);
         let box_address = registers[0];
         unsafe {
             let dm_object = Box::from_raw(box_address as *mut DmObject);
-            assert_eq!(0xff, *dm_object.pointer);
-            dealloc(dm_object.pointer, dm_object.layout);
+            assert_eq!(0xff, *dm_object.data);
+            dealloc(dm_object.data, dm_object.layout);
         }
     }
 
@@ -163,6 +203,6 @@ mod tests {
         let (mut registers, mut register_types) = init_registers(1);
         run(&code, &mut registers, &mut register_types);
         assert_eq!(0, registers[0]);
-        assert_eq!(RegisterType::Int, register_types[0]);
+        assert_eq!(DmType::Int, register_types[0]);
     }
 }
diff --git a/src/vm/module.rs b/src/vm/module.rs
index 6595fc7..d8e4283 100644
--- a/src/vm/module.rs
+++ b/src/vm/module.rs
@@ -22,8 +22,8 @@ pub enum DmConstant {
 }
 
 pub struct DmFunction {
-    name: String,
-    byte_code: Vec<u8>,
+    pub name: String,
+    pub byte_code: Vec<u8>,
 }
 
 const CONST_SYMBOL: u8 = 0x01;
diff --git a/src/vm/op_codes.rs b/src/vm/op_codes.rs
index 9e202ef..7b0bdde 100644
--- a/src/vm/op_codes.rs
+++ b/src/vm/op_codes.rs
@@ -1,3 +1,5 @@
+use crate::push_bytes;
+
 /// ## mov(register: u8, operand: u32)
 /// - 0: opcode
 /// - 1: register
@@ -35,20 +37,24 @@ pub const MOV_LONG_TO: u8 = 0x08;
 pub const MOV_DOUBLE_TO: u8 = 0x09;
 pub const MOV_REGISTER_TO: u8 = 0x0a;
 
-#[derive(PartialEq, Eq, Clone, Debug)]
-pub enum RegisterType {
-    Int,
-    Long,
-    Double,
-    Pointer,
+pub const PLATFORM_CALL: u8 = 0x10;
+
+macro_rules! push_number {
+    ( $dest: expr, $num: expr ) => {
+        push_bytes!($dest, $num.to_le_bytes())
+    }
+}
+
+macro_rules! push_string {
+    ( $dest: expr, $s: expr ) => {
+        push_bytes!($dest, $s.bytes())
+    };
 }
 
 pub fn add_mov_int(code: &mut Vec<u8>, register: u8, operand: u32) {
     code.push(MOV_INT);
     code.push(register);
-    for b in operand.to_le_bytes() {
-        code.push(b);
-    }
+    push_number!(code, operand);
 }
 
 pub fn add_mov_register(code: &mut Vec<u8>, target_register: u8, source_register: u8) {
@@ -60,9 +66,7 @@ pub fn add_mov_register(code: &mut Vec<u8>, target_register: u8, source_register
 pub fn add_alloc(code: &mut Vec<u8>, register: u8, size: u32) {
     code.push(ALLOC);
     code.push(register);
-    for b in size.to_le_bytes() {
-        code.push(b);
-    }
+    push_number!(code, size);
 }
 
 pub fn add_dealloc(code: &mut Vec<u8>, register: u8) {
@@ -73,10 +77,12 @@ pub fn add_dealloc(code: &mut Vec<u8>, register: u8) {
 pub fn add_mov_int_to(code: &mut Vec<u8>, register: u8, offset: u32, operand: u32) {
     code.push(MOV_INT_TO);
     code.push(register);
-    for b in offset.to_le_bytes() {
-        code.push(b);
-    }
-    for b in operand.to_le_bytes() {
-        code.push(b);
-    }
+    push_number!(code, offset);
+    push_number!(code, operand);
+}
+
+pub fn add_platform_call_to(code: &mut Vec<u8>, symbol_name: &String) {
+    code.push(PLATFORM_CALL);
+    push_number!(code, symbol_name.len());
+    push_string!(code, symbol_name);
 }
diff --git a/src/vm/platform/mod.rs b/src/vm/platform/mod.rs
new file mode 100644
index 0000000..5fd67b8
--- /dev/null
+++ b/src/vm/platform/mod.rs
@@ -0,0 +1,17 @@
+use std::collections::HashMap;
+use crate::vm::{DmVirtualMachine, PlatformFunction};
+use crate::vm::platform::std_lib::core::dm_print;
+
+mod std_lib;
+
+pub struct PlatformCallFrame {
+    args: Vec<u64>,
+    arg_types: Vec<crate::vm::types::DmType>,
+    vm: DmVirtualMachine
+}
+
+pub fn init_platform_functions() -> HashMap<String, PlatformFunction> {
+    let mut m: HashMap<String, PlatformFunction> = HashMap::new();
+    m.insert(String::from("std::core::print"), dm_print);
+    m
+}
\ No newline at end of file
diff --git a/src/vm/platform/std_lib/core.rs b/src/vm/platform/std_lib/core.rs
new file mode 100644
index 0000000..af809b2
--- /dev/null
+++ b/src/vm/platform/std_lib/core.rs
@@ -0,0 +1,42 @@
+use crate::vm::platform::PlatformCallFrame;
+use crate::vm::types::DmType;
+use crate::vm::DmObject;
+use DmType::*;
+
+pub struct DmString {
+    data: String
+}
+
+pub fn dm_print(frame: &mut PlatformCallFrame) -> Result<Option<(u64, DmType)>, String> {
+    if frame.args.len() != 1 {
+        return Err(String::from("std::core::print requires one argument."));
+    }
+    match frame.arg_types[0] {
+        Int => {
+            print!("{}", frame.args[0] as i32);
+        }
+        Long => {
+            print!("{}", frame.args[0] as i64);
+        }
+        Double => {
+            print!("{}", frame.args[0] as f64);
+        }
+        Pointer => unsafe {
+            let dm_object = Box::from_raw(frame.args[0] as *mut DmObject);
+            if let Some(&ref to_string_method) = dm_object.object_type.methods.get(&String::from("to_string")) {
+                let call_result = frame.vm.call(to_string_method, vec![frame.args[0]], vec![Pointer]);
+                if call_result.is_err() {
+                    return Err(call_result.unwrap_err());
+                }
+                let (dm_string_address, _) = call_result?;
+                // TODO: check that it's actually a DmString
+                let dm_string = Box::from_raw(dm_string_address as *mut DmString);
+                print!("{}", dm_string.data);
+            } else {
+                print!("{}@{:?}", dm_object.object_type.name, dm_object.data);
+            }
+        }
+    }
+    Ok(None)
+}
+
diff --git a/src/vm/platform/std_lib/mod.rs b/src/vm/platform/std_lib/mod.rs
new file mode 100644
index 0000000..689cad3
--- /dev/null
+++ b/src/vm/platform/std_lib/mod.rs
@@ -0,0 +1 @@
+pub mod core;
\ No newline at end of file
diff --git a/src/vm/types.rs b/src/vm/types.rs
new file mode 100644
index 0000000..2c3ecab
--- /dev/null
+++ b/src/vm/types.rs
@@ -0,0 +1,7 @@
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub enum DmType {
+    Int,
+    Long,
+    Double,
+    Pointer,
+}
\ No newline at end of file
diff --git a/src/vm/util.rs b/src/vm/util.rs
index b9dbf7d..f08cfff 100644
--- a/src/vm/util.rs
+++ b/src/vm/util.rs
@@ -22,5 +22,15 @@ macro_rules! get_64_le {
     };
 }
 
+#[macro_export]
+macro_rules! push_bytes {
+    ( $dest: expr, $src: expr ) => {
+        for b in $src {
+            $dest.push(b);
+        }
+    };
+}
+
 pub use get_32_le;
 pub use get_64_le;
+pub use push_bytes;