diff --git a/examples/load.rs b/examples/load.rs
index e872ff6..fec2d16 100644
--- a/examples/load.rs
+++ b/examples/load.rs
@@ -2,7 +2,7 @@ use std::{env::args_os, fs::File, io::BufReader, process::exit};
 
 use blotter::BlotterFile;
 
-fn main() -> Result<(), blotter::Error> {
+fn main() -> Result<(), blotter::error::Error> {
     let infile = args_os().nth(1).unwrap_or_else(usage);
     let mut reader = BufReader::new(File::open(infile)?);
     let blotter_file = BlotterFile::read(&mut reader)?;
diff --git a/examples/roundtrip.rs b/examples/roundtrip.rs
index ae8cf8d..613d9d1 100644
--- a/examples/roundtrip.rs
+++ b/examples/roundtrip.rs
@@ -2,7 +2,7 @@ use std::{env::args_os, fs::File, io::BufReader, process::exit};
 
 use blotter::BlotterFile;
 
-fn main() -> Result<(), blotter::Error> {
+fn main() -> Result<(), blotter::error::Error> {
     let infile = args_os().nth(1).unwrap_or_else(usage);
     let mut reader = BufReader::new(File::open(infile)?);
     let blotter_file = BlotterFile::read(&mut reader)?;
diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..6ec2e15
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,13 @@
+#[derive(Debug)]
+#[non_exhaustive]
+pub enum Error {
+    IoError(std::io::Error),
+    InvalidSave,
+    IncompatibleVersion(u8),
+}
+
+impl From<std::io::Error> for Error {
+    fn from(error: std::io::Error) -> Self {
+        Self::IoError(error)
+    }
+}
diff --git a/src/io.rs b/src/io.rs
new file mode 100644
index 0000000..08a85c9
--- /dev/null
+++ b/src/io.rs
@@ -0,0 +1,120 @@
+use crate::error::Error;
+use std::io::{Read, Write};
+
+pub fn read_u8<R: Read>(reader: &mut R) -> Result<u8, Error> {
+    let mut bytes = [0u8; 1];
+    reader.read_exact(&mut bytes)?;
+    Ok(u8::from_le_bytes(bytes))
+}
+
+pub fn write_u8<W: Write>(v: u8, writer: &mut W) -> Result<(), Error> {
+    writer.write_all(&v.to_le_bytes())?;
+    Ok(())
+}
+
+pub fn read_u16<R: Read>(reader: &mut R) -> Result<u16, Error> {
+    let mut bytes = [0u8; 2];
+    reader.read_exact(&mut bytes)?;
+    Ok(u16::from_le_bytes(bytes))
+}
+
+pub fn write_u16<W: Write>(v: u16, writer: &mut W) -> Result<(), Error> {
+    writer.write_all(&v.to_le_bytes())?;
+    Ok(())
+}
+
+pub fn read_i32<R: Read>(reader: &mut R) -> Result<i32, Error> {
+    let mut bytes = [0u8; 4];
+    reader.read_exact(&mut bytes)?;
+    Ok(i32::from_le_bytes(bytes))
+}
+
+pub fn write_i32<W: Write>(v: i32, writer: &mut W) -> Result<(), Error> {
+    writer.write_all(&v.to_le_bytes())?;
+    Ok(())
+}
+
+pub fn read_u32<R: Read>(reader: &mut R) -> Result<u32, Error> {
+    let mut bytes = [0u8; 4];
+    reader.read_exact(&mut bytes)?;
+    Ok(u32::from_le_bytes(bytes))
+}
+
+pub fn write_u32<W: Write>(v: u32, writer: &mut W) -> Result<(), Error> {
+    writer.write_all(&v.to_le_bytes())?;
+    Ok(())
+}
+
+pub fn read_f32<R: Read>(reader: &mut R) -> Result<f32, Error> {
+    let mut bytes = [0u8; 4];
+    reader.read_exact(&mut bytes)?;
+    Ok(f32::from_le_bytes(bytes))
+}
+
+pub fn write_f32<W: Write>(v: f32, writer: &mut W) -> Result<(), Error> {
+    writer.write_all(&v.to_le_bytes())?;
+    Ok(())
+}
+
+pub fn read_usize<R: Read>(reader: &mut R) -> Result<usize, Error> {
+    read_i32(reader)?.try_into().map_err(|_| Error::InvalidSave)
+}
+
+pub fn write_usize<W: Write>(v: usize, writer: &mut W) -> Result<(), Error> {
+    let v: i32 = v.try_into().map_err(|_| Error::InvalidSave)?;
+    write_i32(v, writer)
+}
+
+pub fn read_string<R: Read>(reader: &mut R) -> Result<String, Error> {
+    let string_len = read_usize(reader)?;
+    let bytes = read_bytevec(reader, string_len)?;
+    String::from_utf8(bytes).map_err(|_| Error::InvalidSave)
+}
+
+pub fn write_str<W: Write>(s: &str, writer: &mut W) -> Result<(), Error> {
+    write_usize(s.len(), writer)?;
+    writer.write_all(s.as_bytes())?;
+    Ok(())
+}
+
+pub fn read_vec<F, T>(len: usize, mut reader: F) -> Result<Vec<T>, Error>
+where
+    F: FnMut() -> Result<T, Error>,
+{
+    let mut vec = Vec::with_capacity(len);
+    for _ in 0..len {
+        vec.push(reader()?);
+    }
+    Ok(vec)
+}
+
+pub fn read_array<F, T, const LEN: usize>(mut reader: F) -> Result<[T; LEN], Error>
+where
+    F: FnMut() -> Result<T, Error>,
+    T: Default + Copy,
+{
+    let mut arr = [Default::default(); LEN];
+    for slot in &mut arr {
+        *slot = reader()?;
+    }
+    Ok(arr)
+}
+
+pub fn read_magic<R: Read>(reader: &mut R, magic_bytes: &[u8]) -> Result<(), Error> {
+    let mut header = [0u8; 16];
+    reader.read_exact(&mut header)?;
+    if header != *magic_bytes {
+        return Err(Error::InvalidSave);
+    }
+    Ok(())
+}
+
+pub fn read_version<R: Read>(reader: &mut R) -> Result<[i32; 4], Error> {
+    read_array(|| read_i32(reader))
+}
+
+pub fn read_bytevec<R: Read>(reader: &mut R, len: usize) -> Result<Vec<u8>, Error> {
+    let mut vec = vec![0u8; len];
+    reader.read_exact(&mut vec)?;
+    Ok(vec)
+}
diff --git a/src/lib.rs b/src/lib.rs
index 8c0439b..40a2c69 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,517 +1,31 @@
+pub mod error;
+pub(crate) mod io;
+pub mod v5;
+
+use io::read_u8;
 use std::io::{Read, Write};
 
-#[derive(Debug, Clone, Copy, PartialEq)]
-pub enum SaveType {
-    World,
-    Subassembly,
-}
+use crate::error::Error;
+use crate::io::read_magic;
 
 #[derive(Debug)]
-pub struct ModInfo {
-    pub mod_id: String,
-    pub mod_version: [i32; 4],
-}
-
-#[derive(Debug)]
-pub struct ComponentType {
-    pub numeric_id: u16,
-    pub text_id: String,
-}
-
-#[derive(Debug)]
-pub struct Input {
-    pub circuit_state_id: i32,
-}
-
-#[derive(Debug)]
-pub struct Output {
-    pub circuit_state_id: i32,
-}
-
-#[derive(Debug)]
-pub struct Component {
-    pub address: u32,
-    pub parent: u32,
-    pub type_id: u16,
-    pub position: [f32; 3],
-    pub rotation: [f32; 4],
-    pub inputs: Vec<Input>,
-    pub outputs: Vec<Output>,
-    pub custom_data: Option<Vec<u8>>,
-}
-
-#[derive(Debug)]
-pub struct PegAddress {
-    pub is_input: bool,
-    pub component_address: u32,
-    pub peg_index: i32,
-}
-
-#[derive(Debug)]
-pub struct Wire {
-    pub start_peg: PegAddress,
-    pub end_peg: PegAddress,
-    pub circuit_state_id: i32,
-    pub rotation: f32,
-}
-
-#[derive(Debug)]
-pub enum CircuitStates {
-    WorldFormat { circuit_states: Vec<u8> },
-    SubassemblyFormat { on_states: Vec<i32> },
-}
-
-#[derive(Debug)]
-pub struct BlotterFile {
-    pub save_version: u8,
-    pub game_version: [i32; 4],
-    pub save_type: SaveType,
-    pub mods: Vec<ModInfo>,
-    pub component_types: Vec<ComponentType>,
-    pub components: Vec<Component>,
-    pub wires: Vec<Wire>,
-    pub circuit_states: CircuitStates,
+pub enum BlotterFile {
+    V5(v5::BlotterFile),
 }
 
 impl BlotterFile {
-    pub fn new(game_version: [i32; 4]) -> Self {
-        Self {
-            save_version: 5,
-            game_version,
-            save_type: SaveType::World,
-            mods: Vec::new(),
-            component_types: Vec::new(),
-            components: Vec::new(),
-            wires: Vec::new(),
-            circuit_states: CircuitStates::WorldFormat {
-                circuit_states: Vec::new(),
-            },
-        }
-    }
-
-    pub fn read<R>(reader: &mut R) -> Result<Self, Error>
-    where
-        R: Read,
-    {
+    pub fn read<R: Read>(reader: &mut R) -> Result<Self, Error> {
         read_magic(reader, b"Logic World save")?;
-
         let save_version = read_u8(reader)?;
-        if save_version != 5 {
-            return Err(Error::IncompatibleVersion(save_version));
+        match save_version {
+            5 => v5::BlotterFile::read_after_save_version(reader).map(Self::V5),
+            _ => Err(Error::IncompatibleVersion(save_version)),
         }
-
-        let game_version = read_version(reader)?;
-
-        let save_type_id = read_u8(reader)?;
-        let save_type = match save_type_id {
-            1 => SaveType::World,
-            2 => SaveType::Subassembly,
-            _ => {
-                return Err(Error::InvalidSave);
-            }
-        };
-
-        let num_components = read_usize(reader)?;
-        let num_wires = read_usize(reader)?;
-
-        let num_mods = read_usize(reader)?;
-        let mods = read_vec(num_mods, || {
-            let mod_id = read_string(reader)?;
-            let mod_version = read_version(reader)?;
-            Ok(ModInfo {
-                mod_id,
-                mod_version,
-            })
-        })?;
-
-        let num_component_types: usize = read_usize(reader)?;
-        let component_types = read_vec(num_component_types, || {
-            let numeric_id = read_u16(reader)?;
-            let text_id = read_string(reader)?;
-            Ok(ComponentType {
-                numeric_id,
-                text_id,
-            })
-        })?;
-
-        let components = read_vec(num_components, || {
-            let address = read_u32(reader)?;
-            let parent = read_u32(reader)?;
-            let type_id = read_u16(reader)?;
-            let position = read_array(|| read_f32(reader))?;
-            let rotation = read_array(|| read_f32(reader))?;
-
-            let num_inputs = read_usize(reader)?;
-            let inputs = read_vec(num_inputs, || {
-                let circuit_state_id = read_i32(reader)?;
-                Ok(Input { circuit_state_id })
-            })?;
-
-            let num_outputs = read_usize(reader)?;
-            let outputs = read_vec(num_outputs, || {
-                let circuit_state_id = read_i32(reader)?;
-                Ok(Output { circuit_state_id })
-            })?;
-
-            let custom_data_len = read_i32(reader)?;
-            let custom_data = if custom_data_len < 0 {
-                None
-            } else {
-                Some(read_bytevec(reader, custom_data_len as usize)?)
-            };
-
-            Ok(Component {
-                address,
-                parent,
-                type_id,
-                position,
-                rotation,
-                inputs,
-                outputs,
-                custom_data,
-            })
-        })?;
-
-        let wires = read_vec(num_wires, || {
-            let start_peg = read_peg_address(reader)?;
-            let end_peg = read_peg_address(reader)?;
-            let circuit_state_id = read_i32(reader)?;
-            let rotation = read_f32(reader)?;
-
-            Ok(Wire {
-                start_peg,
-                end_peg,
-                circuit_state_id,
-                rotation,
-            })
-        })?;
-
-        let circuit_states = match save_type {
-            SaveType::World => {
-                let num_bytes = read_usize(reader)?;
-                let circuit_states = read_bytevec(reader, num_bytes)?;
-                CircuitStates::WorldFormat { circuit_states }
-            }
-            SaveType::Subassembly => {
-                let num_on_states = read_usize(reader)?;
-                let on_states = read_vec(num_on_states, || read_i32(reader))?;
-                CircuitStates::SubassemblyFormat { on_states }
-            }
-        };
-
-        read_magic(reader, b"redstone sux lol")?;
-
-        Ok(Self {
-            save_version,
-            game_version,
-            save_type,
-            mods,
-            component_types,
-            components,
-            wires,
-            circuit_states,
-        })
     }
 
-    pub fn write<W>(&self, writer: &mut W) -> Result<(), Error>
-    where
-        W: Write,
-    {
-        writer.write_all(b"Logic World save")?;
-
-        write_u8(self.save_version, writer)?;
-        for &v in &self.game_version {
-            write_i32(v, writer)?;
+    pub fn write<W: Write>(&self, writer: &mut W) -> Result<(), Error> {
+        match self {
+            Self::V5(file) => file.write(writer),
         }
-        let save_type_id = match self.save_type {
-            SaveType::World => 1,
-            SaveType::Subassembly => 2,
-        };
-        write_u8(save_type_id, writer)?;
-
-        write_usize(self.components.len(), writer)?;
-        write_usize(self.wires.len(), writer)?;
-
-        write_usize(self.mods.len(), writer)?;
-        for mod_info in &self.mods {
-            write_str(&mod_info.mod_id, writer)?;
-            for &v in &mod_info.mod_version {
-                write_i32(v, writer)?;
-            }
-        }
-
-        write_usize(self.component_types.len(), writer)?;
-        for component_type in &self.component_types {
-            write_u16(component_type.numeric_id, writer)?;
-            write_str(&component_type.text_id, writer)?;
-        }
-
-        for component in &self.components {
-            write_u32(component.address, writer)?;
-            write_u32(component.parent, writer)?;
-            write_u16(component.type_id, writer)?;
-            for &v in &component.position {
-                write_f32(v, writer)?;
-            }
-            for &v in &component.rotation {
-                write_f32(v, writer)?;
-            }
-            write_usize(component.inputs.len(), writer)?;
-            for input in &component.inputs {
-                write_i32(input.circuit_state_id, writer)?;
-            }
-            write_usize(component.outputs.len(), writer)?;
-            for output in &component.outputs {
-                write_i32(output.circuit_state_id, writer)?;
-            }
-            if let Some(bytes) = &component.custom_data {
-                write_usize(bytes.len(), writer)?;
-                writer.write_all(&bytes)?;
-            } else {
-                write_i32(-1, writer)?;
-            }
-        }
-
-        for wire in &self.wires {
-            write_peg_address(&wire.start_peg, writer)?;
-            write_peg_address(&wire.end_peg, writer)?;
-            write_i32(wire.circuit_state_id, writer)?;
-            write_f32(wire.rotation, writer)?;
-        }
-
-        match (self.save_type, &self.circuit_states) {
-            (SaveType::World, CircuitStates::WorldFormat { circuit_states }) => {
-                write_usize(circuit_states.len(), writer)?;
-                writer.write_all(&circuit_states)?;
-            }
-            (SaveType::Subassembly, CircuitStates::SubassemblyFormat { on_states }) => {
-                write_usize(on_states.len(), writer)?;
-                for &v in on_states {
-                    write_i32(v, writer)?;
-                }
-            }
-            _ => {
-                return Err(Error::InvalidSave);
-            }
-        }
-
-        writer.write_all(b"redstone sux lol")?;
-        Ok(())
     }
 }
-
-#[derive(Debug)]
-#[non_exhaustive]
-pub enum Error {
-    IoError(std::io::Error),
-    InvalidSave,
-    IncompatibleVersion(u8),
-}
-
-impl From<std::io::Error> for Error {
-    fn from(error: std::io::Error) -> Self {
-        Self::IoError(error)
-    }
-}
-
-fn read_u8<R>(reader: &mut R) -> Result<u8, Error>
-where
-    R: Read,
-{
-    let mut bytes = [0u8; 1];
-    reader.read_exact(&mut bytes)?;
-    Ok(u8::from_le_bytes(bytes))
-}
-
-fn read_u16<R>(reader: &mut R) -> Result<u16, Error>
-where
-    R: Read,
-{
-    let mut bytes = [0u8; 2];
-    reader.read_exact(&mut bytes)?;
-    Ok(u16::from_le_bytes(bytes))
-}
-
-fn read_i32<R>(reader: &mut R) -> Result<i32, Error>
-where
-    R: Read,
-{
-    let mut bytes = [0u8; 4];
-    reader.read_exact(&mut bytes)?;
-    Ok(i32::from_le_bytes(bytes))
-}
-
-fn read_u32<R>(reader: &mut R) -> Result<u32, Error>
-where
-    R: Read,
-{
-    let mut bytes = [0u8; 4];
-    reader.read_exact(&mut bytes)?;
-    Ok(u32::from_le_bytes(bytes))
-}
-
-fn read_f32<R>(reader: &mut R) -> Result<f32, Error>
-where
-    R: Read,
-{
-    let mut bytes = [0u8; 4];
-    reader.read_exact(&mut bytes)?;
-    Ok(f32::from_le_bytes(bytes))
-}
-
-fn read_usize<R>(reader: &mut R) -> Result<usize, Error>
-where
-    R: Read,
-{
-    read_i32(reader)?.try_into().map_err(|_| Error::InvalidSave)
-}
-
-fn read_string<R>(reader: &mut R) -> Result<String, Error>
-where
-    R: Read,
-{
-    let string_len = read_usize(reader)?;
-    let bytes = read_bytevec(reader, string_len)?;
-    String::from_utf8(bytes).map_err(|_| Error::InvalidSave)
-}
-
-fn read_vec<F, T>(len: usize, mut reader: F) -> Result<Vec<T>, Error>
-where
-    F: FnMut() -> Result<T, Error>,
-{
-    let mut vec = Vec::with_capacity(len);
-    for _ in 0..len {
-        vec.push(reader()?);
-    }
-    Ok(vec)
-}
-
-fn read_array<F, T, const LEN: usize>(mut reader: F) -> Result<[T; LEN], Error>
-where
-    F: FnMut() -> Result<T, Error>,
-    T: Default + Copy,
-{
-    let mut arr = [Default::default(); LEN];
-    for slot in &mut arr {
-        *slot = reader()?;
-    }
-    Ok(arr)
-}
-
-fn read_magic<R>(reader: &mut R, magic_bytes: &[u8]) -> Result<(), Error>
-where
-    R: Read,
-{
-    let mut header = [0u8; 16];
-    reader.read_exact(&mut header)?;
-    if header != *magic_bytes {
-        return Err(Error::InvalidSave);
-    }
-    Ok(())
-}
-
-fn read_version<R>(reader: &mut R) -> Result<[i32; 4], Error>
-where
-    R: Read,
-{
-    read_array(|| read_i32(reader))
-}
-
-fn read_bytevec<R>(reader: &mut R, len: usize) -> Result<Vec<u8>, Error>
-where
-    R: Read,
-{
-    let mut vec = vec![0u8; len];
-    reader.read_exact(&mut vec)?;
-    Ok(vec)
-}
-
-fn read_peg_address<R>(reader: &mut R) -> Result<PegAddress, Error>
-where
-    R: Read,
-{
-    let peg_kind = read_u8(reader)?;
-    let is_input = match peg_kind {
-        0 => false,
-        1 => true,
-        _ => return Err(Error::InvalidSave),
-    };
-    let component_address = read_u32(reader)?;
-    let peg_index = read_i32(reader)?;
-    Ok(PegAddress {
-        is_input,
-        component_address,
-        peg_index,
-    })
-}
-
-fn write_u8<W>(v: u8, writer: &mut W) -> Result<(), Error>
-where
-    W: Write,
-{
-    writer.write_all(&v.to_le_bytes())?;
-    Ok(())
-}
-
-fn write_u16<W>(v: u16, writer: &mut W) -> Result<(), Error>
-where
-    W: Write,
-{
-    writer.write_all(&v.to_le_bytes())?;
-    Ok(())
-}
-
-fn write_i32<W>(v: i32, writer: &mut W) -> Result<(), Error>
-where
-    W: Write,
-{
-    writer.write_all(&v.to_le_bytes())?;
-    Ok(())
-}
-
-fn write_u32<W>(v: u32, writer: &mut W) -> Result<(), Error>
-where
-    W: Write,
-{
-    writer.write_all(&v.to_le_bytes())?;
-    Ok(())
-}
-
-fn write_f32<W>(v: f32, writer: &mut W) -> Result<(), Error>
-where
-    W: Write,
-{
-    writer.write_all(&v.to_le_bytes())?;
-    Ok(())
-}
-
-fn write_usize<W>(v: usize, writer: &mut W) -> Result<(), Error>
-where
-    W: Write,
-{
-    let v: i32 = v.try_into().map_err(|_| Error::InvalidSave)?;
-    write_i32(v, writer)
-}
-
-fn write_str<W>(s: &str, writer: &mut W) -> Result<(), Error>
-where
-    W: Write,
-{
-    write_usize(s.len(), writer)?;
-    writer.write_all(s.as_bytes())?;
-    Ok(())
-}
-
-fn write_peg_address<W>(address: &PegAddress, writer: &mut W) -> Result<(), Error>
-where
-    W: Write,
-{
-    let peg_type_id = match address.is_input {
-        false => 0,
-        true => 1,
-    };
-    write_u8(peg_type_id, writer)?;
-    write_u32(address.component_address, writer)?;
-    write_i32(address.peg_index, writer)?;
-    Ok(())
-}
diff --git a/src/v5.rs b/src/v5.rs
new file mode 100644
index 0000000..7fa2616
--- /dev/null
+++ b/src/v5.rs
@@ -0,0 +1,327 @@
+use crate::error::Error;
+use crate::io::*;
+use std::io::{Read, Write};
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum SaveType {
+    World,
+    Subassembly,
+}
+
+#[derive(Debug)]
+pub struct ModInfo {
+    pub mod_id: String,
+    pub mod_version: [i32; 4],
+}
+
+#[derive(Debug)]
+pub struct ComponentType {
+    pub numeric_id: u16,
+    pub text_id: String,
+}
+
+#[derive(Debug)]
+pub struct Input {
+    pub circuit_state_id: i32,
+}
+
+#[derive(Debug)]
+pub struct Output {
+    pub circuit_state_id: i32,
+}
+
+#[derive(Debug)]
+pub struct Component {
+    pub address: u32,
+    pub parent: u32,
+    pub type_id: u16,
+    pub position: [f32; 3],
+    pub rotation: [f32; 4],
+    pub inputs: Vec<Input>,
+    pub outputs: Vec<Output>,
+    pub custom_data: Option<Vec<u8>>,
+}
+
+#[derive(Debug)]
+pub struct PegAddress {
+    pub is_input: bool,
+    pub component_address: u32,
+    pub peg_index: i32,
+}
+
+#[derive(Debug)]
+pub struct Wire {
+    pub start_peg: PegAddress,
+    pub end_peg: PegAddress,
+    pub circuit_state_id: i32,
+    pub rotation: f32,
+}
+
+#[derive(Debug)]
+pub enum CircuitStates {
+    WorldFormat { circuit_states: Vec<u8> },
+    SubassemblyFormat { on_states: Vec<i32> },
+}
+
+#[derive(Debug)]
+pub struct BlotterFile {
+    pub save_version: u8,
+    pub game_version: [i32; 4],
+    pub save_type: SaveType,
+    pub mods: Vec<ModInfo>,
+    pub component_types: Vec<ComponentType>,
+    pub components: Vec<Component>,
+    pub wires: Vec<Wire>,
+    pub circuit_states: CircuitStates,
+}
+
+impl BlotterFile {
+    pub fn new(game_version: [i32; 4]) -> Self {
+        Self {
+            save_version: 5,
+            game_version,
+            save_type: SaveType::World,
+            mods: Vec::new(),
+            component_types: Vec::new(),
+            components: Vec::new(),
+            wires: Vec::new(),
+            circuit_states: CircuitStates::WorldFormat {
+                circuit_states: Vec::new(),
+            },
+        }
+    }
+
+    pub fn read<R: Read>(reader: &mut R) -> Result<Self, Error> {
+        read_magic(reader, b"Logic World save")?;
+
+        let save_version = read_u8(reader)?;
+        if save_version != 5 {
+            return Err(Error::IncompatibleVersion(save_version));
+        }
+        Self::read_after_save_version(reader)
+    }
+
+    pub(crate) fn read_after_save_version<R: Read>(reader: &mut R) -> Result<Self, Error> {
+        let game_version = read_version(reader)?;
+
+        let save_type_id = read_u8(reader)?;
+        let save_type = match save_type_id {
+            1 => SaveType::World,
+            2 => SaveType::Subassembly,
+            _ => {
+                return Err(Error::InvalidSave);
+            }
+        };
+
+        let num_components = read_usize(reader)?;
+        let num_wires = read_usize(reader)?;
+
+        let num_mods = read_usize(reader)?;
+        let mods = read_vec(num_mods, || {
+            let mod_id = read_string(reader)?;
+            let mod_version = read_version(reader)?;
+            Ok(ModInfo {
+                mod_id,
+                mod_version,
+            })
+        })?;
+
+        let num_component_types: usize = read_usize(reader)?;
+        let component_types = read_vec(num_component_types, || {
+            let numeric_id = read_u16(reader)?;
+            let text_id = read_string(reader)?;
+            Ok(ComponentType {
+                numeric_id,
+                text_id,
+            })
+        })?;
+
+        let components = read_vec(num_components, || {
+            let address = read_u32(reader)?;
+            let parent = read_u32(reader)?;
+            let type_id = read_u16(reader)?;
+            let position = read_array(|| read_f32(reader))?;
+            let rotation = read_array(|| read_f32(reader))?;
+
+            let num_inputs = read_usize(reader)?;
+            let inputs = read_vec(num_inputs, || {
+                let circuit_state_id = read_i32(reader)?;
+                Ok(Input { circuit_state_id })
+            })?;
+
+            let num_outputs = read_usize(reader)?;
+            let outputs = read_vec(num_outputs, || {
+                let circuit_state_id = read_i32(reader)?;
+                Ok(Output { circuit_state_id })
+            })?;
+
+            let custom_data_len = read_i32(reader)?;
+            let custom_data = if custom_data_len < 0 {
+                None
+            } else {
+                Some(read_bytevec(reader, custom_data_len as usize)?)
+            };
+
+            Ok(Component {
+                address,
+                parent,
+                type_id,
+                position,
+                rotation,
+                inputs,
+                outputs,
+                custom_data,
+            })
+        })?;
+
+        let wires = read_vec(num_wires, || {
+            let start_peg = read_peg_address(reader)?;
+            let end_peg = read_peg_address(reader)?;
+            let circuit_state_id = read_i32(reader)?;
+            let rotation = read_f32(reader)?;
+
+            Ok(Wire {
+                start_peg,
+                end_peg,
+                circuit_state_id,
+                rotation,
+            })
+        })?;
+
+        let circuit_states = match save_type {
+            SaveType::World => {
+                let num_bytes = read_usize(reader)?;
+                let circuit_states = read_bytevec(reader, num_bytes)?;
+                CircuitStates::WorldFormat { circuit_states }
+            }
+            SaveType::Subassembly => {
+                let num_on_states = read_usize(reader)?;
+                let on_states = read_vec(num_on_states, || read_i32(reader))?;
+                CircuitStates::SubassemblyFormat { on_states }
+            }
+        };
+
+        read_magic(reader, b"redstone sux lol")?;
+
+        Ok(Self {
+            save_version: 5,
+            game_version,
+            save_type,
+            mods,
+            component_types,
+            components,
+            wires,
+            circuit_states,
+        })
+    }
+
+    pub fn write<W: Write>(&self, writer: &mut W) -> Result<(), Error> {
+        writer.write_all(b"Logic World save")?;
+
+        write_u8(self.save_version, writer)?;
+        for &v in &self.game_version {
+            write_i32(v, writer)?;
+        }
+        let save_type_id = match self.save_type {
+            SaveType::World => 1,
+            SaveType::Subassembly => 2,
+        };
+        write_u8(save_type_id, writer)?;
+
+        write_usize(self.components.len(), writer)?;
+        write_usize(self.wires.len(), writer)?;
+
+        write_usize(self.mods.len(), writer)?;
+        for mod_info in &self.mods {
+            write_str(&mod_info.mod_id, writer)?;
+            for &v in &mod_info.mod_version {
+                write_i32(v, writer)?;
+            }
+        }
+
+        write_usize(self.component_types.len(), writer)?;
+        for component_type in &self.component_types {
+            write_u16(component_type.numeric_id, writer)?;
+            write_str(&component_type.text_id, writer)?;
+        }
+
+        for component in &self.components {
+            write_u32(component.address, writer)?;
+            write_u32(component.parent, writer)?;
+            write_u16(component.type_id, writer)?;
+            for &v in &component.position {
+                write_f32(v, writer)?;
+            }
+            for &v in &component.rotation {
+                write_f32(v, writer)?;
+            }
+            write_usize(component.inputs.len(), writer)?;
+            for input in &component.inputs {
+                write_i32(input.circuit_state_id, writer)?;
+            }
+            write_usize(component.outputs.len(), writer)?;
+            for output in &component.outputs {
+                write_i32(output.circuit_state_id, writer)?;
+            }
+            if let Some(bytes) = &component.custom_data {
+                write_usize(bytes.len(), writer)?;
+                writer.write_all(&bytes)?;
+            } else {
+                write_i32(-1, writer)?;
+            }
+        }
+
+        for wire in &self.wires {
+            write_peg_address(&wire.start_peg, writer)?;
+            write_peg_address(&wire.end_peg, writer)?;
+            write_i32(wire.circuit_state_id, writer)?;
+            write_f32(wire.rotation, writer)?;
+        }
+
+        match (self.save_type, &self.circuit_states) {
+            (SaveType::World, CircuitStates::WorldFormat { circuit_states }) => {
+                write_usize(circuit_states.len(), writer)?;
+                writer.write_all(&circuit_states)?;
+            }
+            (SaveType::Subassembly, CircuitStates::SubassemblyFormat { on_states }) => {
+                write_usize(on_states.len(), writer)?;
+                for &v in on_states {
+                    write_i32(v, writer)?;
+                }
+            }
+            _ => {
+                return Err(Error::InvalidSave);
+            }
+        }
+
+        writer.write_all(b"redstone sux lol")?;
+        Ok(())
+    }
+}
+
+fn read_peg_address<R: Read>(reader: &mut R) -> Result<PegAddress, Error> {
+    let peg_kind = read_u8(reader)?;
+    let is_input = match peg_kind {
+        0 => false,
+        1 => true,
+        _ => return Err(Error::InvalidSave),
+    };
+    let component_address = read_u32(reader)?;
+    let peg_index = read_i32(reader)?;
+    Ok(PegAddress {
+        is_input,
+        component_address,
+        peg_index,
+    })
+}
+
+fn write_peg_address<W: Write>(address: &PegAddress, writer: &mut W) -> Result<(), Error> {
+    let peg_type_id = match address.is_input {
+        false => 0,
+        true => 1,
+    };
+    write_u8(peg_type_id, writer)?;
+    write_u32(address.component_address, writer)?;
+    write_i32(address.peg_index, writer)?;
+    Ok(())
+}