diff --git a/build.rs b/build.rs
index 57b8731..befe091 100644
--- a/build.rs
+++ b/build.rs
@@ -18,6 +18,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     };
     builder
         .include(Path::new("shrooms-vb-core/core"))
+        .include(Path::new("shrooms-vb-core/util"))
         .opt_level(opt_level)
         .flag_if_supported("-fno-strict-aliasing")
         .define("VB_LITTLE_ENDIAN", None)
@@ -29,7 +30,10 @@ fn main() -> Result<(), Box<dyn Error>> {
         .define("VB_DIRECT_FRAME", "on_frame")
         .define("VB_DIRECT_READ", "on_read")
         .define("VB_DIRECT_WRITE", "on_write")
+        .define("VBU_REALLOC", "vbu_realloc_shim")
         .file(Path::new("shrooms-vb-core/core/vb.c"))
+        .file(Path::new("shrooms-vb-core/util/isx.c"))
+        .file(Path::new("shrooms-vb-core/util/vbu.c"))
         .compile("vb");
 
     Ok(())
diff --git a/src/emulator.rs b/src/emulator.rs
index 5c2c91c..072040e 100644
--- a/src/emulator.rs
+++ b/src/emulator.rs
@@ -33,6 +33,7 @@ mod cart;
 mod game_info;
 mod inline_stack_map;
 mod shrooms_vb_core;
+mod shrooms_vb_util;
 
 #[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
 pub enum SimId {
diff --git a/src/emulator/cart.rs b/src/emulator/cart.rs
index 6bab2a7..4bb6a39 100644
--- a/src/emulator/cart.rs
+++ b/src/emulator/cart.rs
@@ -7,7 +7,7 @@ use std::{
     sync::Arc,
 };
 
-use crate::emulator::{SimId, game_info::GameInfo};
+use crate::emulator::{SimId, game_info::GameInfo, shrooms_vb_util::rom_from_isx};
 
 pub struct Cart {
     pub file_path: PathBuf,
@@ -20,8 +20,9 @@ pub struct Cart {
 impl Cart {
     pub fn load(file_path: &Path, sim_id: SimId) -> Result<Self> {
         let rom = fs::read(file_path)?;
-        let (rom, info) =
-            try_parse_elf(file_path, &rom).unwrap_or_else(|| (rom, GameInfo::empty(file_path)));
+        let (rom, info) = try_parse_isx(file_path, &rom)
+            .or_else(|| try_parse_elf(file_path, &rom))
+            .unwrap_or_else(|| (rom, GameInfo::empty(file_path)));
 
         let mut sram_file = File::options()
             .read(true)
@@ -60,6 +61,12 @@ impl Cart {
     }
 }
 
+fn try_parse_isx(file_path: &Path, data: &[u8]) -> Option<(Vec<u8>, GameInfo)> {
+    let rom = rom_from_isx(data)?;
+    let info = GameInfo::from_isx(file_path, data);
+    Some((rom, info))
+}
+
 fn try_parse_elf(file_path: &Path, data: &[u8]) -> Option<(Vec<u8>, GameInfo)> {
     use object::read::elf::FileHeader;
     let program = match object::FileKind::parse(data).ok()? {
@@ -73,7 +80,7 @@ fn try_parse_elf(file_path: &Path, data: &[u8]) -> Option<(Vec<u8>, GameInfo)> {
         }
         _ => return None,
     };
-    let info = GameInfo::new(file_path, data).unwrap_or_else(|_| GameInfo::empty(file_path));
+    let info = GameInfo::from_elf(file_path, data).unwrap_or_else(|_| GameInfo::empty(file_path));
     Some((program, info))
 }
 
diff --git a/src/emulator/game_info.rs b/src/emulator/game_info.rs
index 9f72e7c..5c1ff8e 100644
--- a/src/emulator/game_info.rs
+++ b/src/emulator/game_info.rs
@@ -14,7 +14,7 @@ pub struct GameInfo {
 }
 
 impl GameInfo {
-    pub fn new(file_path: &Path, input: &[u8]) -> Result<Self> {
+    pub fn from_elf(file_path: &Path, input: &[u8]) -> Result<Self> {
         let file = object::File::parse(input)?;
 
         let (name, path) = name_and_path(file_path);
@@ -52,6 +52,26 @@ impl GameInfo {
         })
     }
 
+    pub fn from_isx(file_path: &Path, input: &[u8]) -> Self {
+        let (name, path) = name_and_path(file_path);
+        let symbols = extract_isx_symbols(input);
+        let library_info = LibraryInfo {
+            name: name.clone(),
+            debug_name: name,
+            path: path.clone(),
+            debug_path: path,
+            debug_id: DebugId::default(),
+            code_id: None,
+            arch: None,
+            symbol_table: symbols.map(|syms| Arc::new(SymbolTable::new(syms))),
+        };
+        let inline_stack_map = InlineStackMap::empty();
+        Self {
+            library_info,
+            inline_stack_map,
+        }
+    }
+
     pub fn empty(file_path: &Path) -> Self {
         let (name, path) = name_and_path(file_path);
         let library_info = LibraryInfo {
@@ -115,6 +135,66 @@ fn build_inline_stack_map(file: object::File) -> Result<InlineStackMap> {
     Ok(frames.build())
 }
 
+fn extract_isx_symbols(input: &[u8]) -> Option<Vec<Symbol>> {
+    let mut syms = vec![];
+    let (_, mut buf) = input.split_at_checked(32)?;
+    while !buf.is_empty() {
+        let typ;
+        (typ, buf) = buf.split_first()?;
+        match typ {
+            0x11 => {
+                // Code (Virtual Boy)
+                (_, buf) = buf.split_at_checked(4)?;
+                let len_bytes;
+                (len_bytes, buf) = buf.split_first_chunk()?;
+                let len = u32::from_le_bytes(*len_bytes);
+                (_, buf) = buf.split_at_checked(len as usize)?;
+            }
+            0x13 => {
+                // Range (Virtual Boy)
+                let count_bytes;
+                (count_bytes, buf) = buf.split_first_chunk()?;
+                let count = u16::from_le_bytes(*count_bytes) + 1;
+                (_, buf) = buf.split_at_checked(count as usize * 9)?;
+            }
+            0x14 => {
+                // Symbol (Virtual Boy)
+                let count_bytes;
+                (count_bytes, buf) = buf.split_first_chunk()?;
+                let count = u16::from_le_bytes(*count_bytes) + 1;
+                for _ in 0..count {
+                    let name_len;
+                    (name_len, buf) = buf.split_first()?;
+                    let name_bytes;
+                    (name_bytes, buf) = buf.split_at_checked(*name_len as usize)?;
+                    (_, buf) = buf.split_at_checked(2)?;
+                    let address_bytes;
+                    (address_bytes, buf) = buf.split_first_chunk()?;
+
+                    let name_str = String::from_utf8_lossy(name_bytes);
+                    let address = u32::from_le_bytes(*address_bytes);
+                    syms.push(Symbol {
+                        address,
+                        size: Some(4),
+                        name: demangle_any(&name_str),
+                    });
+                }
+            }
+            0x20 | 0x21 | 0x22 => {
+                // System (undocumented)
+                let length_bytes;
+                (length_bytes, buf) = buf.split_first_chunk()?;
+                let length = u32::from_le_bytes(*length_bytes);
+                (_, buf) = buf.split_at_checked(length as usize)?;
+            }
+            _ => {
+                return None;
+            }
+        }
+    }
+    Some(syms)
+}
+
 type Reader<'a> = gimli::EndianSlice<'a, gimli::RunTimeEndian>;
 
 struct ParseContext<'a> {
diff --git a/src/emulator/shrooms_vb_util.rs b/src/emulator/shrooms_vb_util.rs
new file mode 100644
index 0000000..c6a8675
--- /dev/null
+++ b/src/emulator/shrooms_vb_util.rs
@@ -0,0 +1,33 @@
+use std::ffi::c_void;
+
+#[unsafe(no_mangle)]
+unsafe fn vbu_realloc_shim(ptr: *mut c_void, new_size: usize) -> *mut c_void {
+    if !ptr.is_null() {
+        // not supporting proper realloc because it needs bookkeeping and it's unnecessary
+        return std::ptr::null_mut();
+    }
+    let allocation = vec![0u8; new_size].into_boxed_slice();
+    Box::into_raw(allocation).cast()
+}
+
+#[link(name = "vb")]
+unsafe extern "C" {
+    #[link_name = "vbuFromISX"]
+    fn vbu_from_isx(bytes: *const c_void, length: usize, rom_length: *mut usize) -> *mut c_void;
+}
+
+pub fn rom_from_isx(bytes: &[u8]) -> Option<Vec<u8>> {
+    if !bytes.starts_with(b"ISX") {
+        return None;
+    }
+    let mut rom_length = 0;
+    let raw_rom =
+        unsafe { vbu_from_isx(bytes.as_ptr().cast(), bytes.len(), &mut rom_length) };
+    if raw_rom.is_null() {
+        return None;
+    }
+    // SAFETY: the rom was allocated by vbu_realloc_shim, which created it from a Vec<u8>.
+    let rom =
+        unsafe { Vec::from_raw_parts(raw_rom.cast(), rom_length, rom_length) };
+    Some(rom)
+}