diff --git a/build.zig b/build.zig
index d13ff59..cd8a907 100644
--- a/build.zig
+++ b/build.zig
@@ -62,6 +62,7 @@ pub fn build(b: *std.Build) void {
     });
     emulator.linkLibC();
     emulator.linkSystemLibrary("lua");
+    emulator.linkSystemLibrary("raylib");
     emulator.addCSourceFiles(.{
         .files = &.{
             "src/testLuaArch.c",
diff --git a/src/components/eeprom.c b/src/components/eeprom.c
index 5f23c94..6e9f92e 100644
--- a/src/components/eeprom.c
+++ b/src/components/eeprom.c
@@ -98,6 +98,15 @@ void nn_eeprom_set(nn_eeprom *eeprom, void *_, nn_component *component, nn_compu
         nn_setCError(computer, "out of space");
         return;
     }
+    if(buf == NULL) {
+        if(data.tag == NN_VALUE_NIL) {
+            buf = "";
+            len = 0;
+        } else {
+            nn_setCError(computer, "bad data (string expected)");
+            return;
+        }
+    }
     eeprom->set(component, eeprom->userdata, buf, len);
     
     nn_eepromControl control = nn_eeprom_getControl(component, eeprom);
@@ -132,8 +141,17 @@ void nn_eeprom_getData(nn_eeprom *eeprom, void *_, nn_component *component, nn_c
 
 void nn_eeprom_setData(nn_eeprom *eeprom, void *_, nn_component *component, nn_computer *computer) {
     nn_value data = nn_getArgument(computer, 0);
-    size_t len;
+    size_t len = 0;
     const char *buf = nn_toString(data, &len);
+    if(buf == NULL) {
+        if(data.tag == NN_VALUE_NIL) {
+            buf = "";
+            len = 0;
+        } else {
+            nn_setCError(computer, "bad data (string expected)");
+            return;
+        }
+    }
     if(len > eeprom->getDataSize(component, eeprom->userdata)) {
         nn_setCError(computer, "out of space");
         return;
diff --git a/src/components/filesystem.c b/src/components/filesystem.c
index d723f4c..da3895b 100644
--- a/src/components/filesystem.c
+++ b/src/components/filesystem.c
@@ -1,4 +1,5 @@
 #include "../neonucleus.h"
+#include <stdio.h>
 #include <string.h>
 
 void nn_fs_destroy(void *_, nn_component *component, nn_filesystem *fs) {
@@ -266,7 +267,7 @@ void nn_fs_list(nn_filesystem *fs, void *_, nn_component *component, nn_computer
         // operation succeeded
         nn_value arr = nn_values_array(fileCount);
         for(size_t i = 0; i < fileCount; i++) {
-            nn_values_set(arr, i, nn_values_cstring(files[i]));
+            nn_values_set(arr, i, nn_values_string(files[i], strlen(files[i])));
             nn_free(files[i]);
         }
         nn_free(files);
@@ -336,7 +337,7 @@ void nn_fs_write(nn_filesystem *fs, void *_, nn_component *component, nn_compute
 
 void nn_fs_read(nn_filesystem *fs, void *_, nn_component *component, nn_computer *computer) {
     nn_value fdValue = nn_getArgument(computer, 0);
-    size_t fd = nn_toInt(fdValue);
+    int fd = nn_toInt(fdValue);
 
     nn_value lenValue = nn_getArgument(computer, 1);
     double len = nn_toNumber(lenValue);
@@ -423,6 +424,5 @@ void nn_loadFilesystemTable(nn_universe *universe) {
 
 nn_component *nn_addFileSystem(nn_computer *computer, nn_address address, int slot, nn_filesystem *filesystem) {
     nn_componentTable *fsTable = nn_queryUserdata(nn_getUniverse(computer), "NN:FILESYSTEM");
-
     return nn_newComponent(computer, address, slot, fsTable, filesystem);
 }
diff --git a/src/emulator.c b/src/emulator.c
index b808890..440f44a 100644
--- a/src/emulator.c
+++ b/src/emulator.c
@@ -1,9 +1,11 @@
 #include <assert.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include "neonucleus.h"
 #include "testLuaArch.h"
+#include <raylib.h>
 
 nn_eepromControl ne_eeprom_getControl(nn_component *component, void *_) {
     return (nn_eepromControl) {
@@ -69,6 +71,126 @@ bool ne_eeprom_isReadonly(nn_component *component, void *userdata) {
 
 void ne_eeprom_makeReadonly(nn_component *component, void *userdata) {}
 
+#define NE_FS_MAX 128
+
+typedef struct ne_fs {
+    FILE *files[NE_FS_MAX];
+    size_t fileLen;
+} ne_fs;
+
+nn_filesystemControl ne_fs_getControl(nn_component *component, ne_fs *_) {
+    return (nn_filesystemControl) {
+        .pretendChunkSize = 512,
+        .pretendRPM = 1800,
+        .writeHeatPerChunk = 0.01,
+        .writeCostPerChunk = 3,
+        .writeEnergyCost = 0.015,
+        .writeLatencyPerChunk = 0.0003,
+        .readEnergyCost = 0.007,
+        .readCostPerChunk = 1,
+        .readLatencyPerChunk = 0.0001,
+        .randomLatencyMin = 0.0005,
+        .randomLatencyMax = 0.0019,
+        .seekCostPerChunk = 1,
+        .motorHeat = 0.03,
+        .motorEnergyCost = 0.5,
+    };
+}
+
+size_t ne_fs_spaceUsed(nn_component *component, void *_) {
+    return 0; // ultra accurate
+}
+
+size_t ne_fs_spaceTotal(nn_component *component, void *_) {
+    return 1*1024*1024;
+}
+
+const char *ne_fs_diskPath(nn_component *component, const char *path) {
+    static char buf[256];
+    const char *root = ne_location(nn_getComponentAddress(component));
+    if(path[0] == '/') {
+        snprintf(buf, 256, "%s%s", root, path);
+    } else {
+        snprintf(buf, 256, "%s/%s", root, path);
+    }
+
+    return buf;
+}
+
+size_t ne_fs_open(nn_component *component, ne_fs *fs, const char *path, const char *mode) {
+    if(fs->fileLen == NE_FS_MAX) {
+        nn_setCError(nn_getComputerOfComponent(component), "too many files");
+        return 0;
+    }
+
+    const char *trueMode = "rb";
+    if(strcmp(mode, "w") == 0) {
+        trueMode = "wb";
+    }
+    if(strcmp(mode, "a") == 0) {
+        trueMode = "ab";
+    }
+
+    const char *p = ne_fs_diskPath(component, path);
+    FILE *f = fopen(p, trueMode);
+
+    if(f == NULL) {
+        nn_setCError(nn_getComputerOfComponent(component), strerror(errno));
+        return 0;
+    }
+
+    for(size_t i = 0; i < fs->fileLen; i++) {
+        if(fs->files[i] == NULL) {
+            fs->files[i] = f;
+            return i;
+        }
+    }
+
+    size_t i = fs->fileLen++;
+    fs->files[i] = f;
+    return i;
+}
+
+bool ne_fs_close(nn_component *component, ne_fs *fs, int fd) {
+    // we pray
+    fclose(fs->files[fd]);
+    fs->files[fd] = NULL;
+    return true;
+}
+
+bool ne_fs_write(nn_component *component, ne_fs *fs, int fd, const char *buf, size_t len) {
+    FILE *f = fs->files[fd];
+    return fwrite(buf, sizeof(char), len, f) > 0;
+}
+
+size_t ne_fs_read(nn_component *component, ne_fs *fs, int fd, char *buf, size_t required) {
+    FILE *f = fs->files[fd];
+    if(feof(f)) return 0;
+    return fread(buf, sizeof(char), required, f);
+}
+
+char **ne_fs_list(nn_component *component, ne_fs *fs, const char *path, size_t *len) {
+    const char *p = ne_fs_diskPath(component, path);
+
+    FilePathList files = LoadDirectoryFiles(p);
+    *len = files.count;
+
+    char **buf = nn_malloc(sizeof(char *) * files.count);
+    for(size_t i = 0; i < files.count; i++) {
+        buf[i] = nn_strdup(GetFileName(files.paths[i]));
+    }
+
+    UnloadDirectoryFiles(files);
+
+    return buf;
+}
+
+bool ne_fs_isDirectory(nn_component *component, ne_fs *fs, const char *path) {
+    const char *p = ne_fs_diskPath(component, path);
+
+    return DirectoryExists(p);
+}
+
 int main() {
     printf("Setting up universe\n");
     nn_universe *universe = nn_newUniverse();
@@ -80,6 +202,7 @@ int main() {
     // 1MB of RAM, 16 components max
     nn_computer *computer = nn_newComputer(universe, "testMachine", arch, NULL, 1*1024*1024, 16);
     nn_setEnergyInfo(computer, 5000, 5000);
+    nn_setCallBudget(computer, 18000);
     nn_addSupportedArchitecture(computer, arch);
 
     nn_eeprom genericEEPROM = {
@@ -101,6 +224,37 @@ int main() {
 
     nn_addEeprom(computer, "luaBios.lua", 0, &genericEEPROM);
 
+    ne_fs fs = {
+        .files = {NULL},
+        .fileLen = 0,
+    };
+
+    nn_filesystem genericFS = {
+        .refc = 0,
+        .userdata = &fs,
+        .deinit = NULL,
+        .control = (void *)ne_fs_getControl,
+        .getLabel = ne_eeprom_getLabel,
+        .setLabel = ne_eeprom_setLabel,
+        .spaceUsed = ne_fs_spaceUsed,
+        .spaceTotal = ne_fs_spaceTotal,
+        .isReadOnly = ne_eeprom_isReadonly,
+        .size = NULL,
+        .remove = NULL,
+        .lastModified = NULL,
+        .rename = NULL,
+        .exists = NULL,
+        .isDirectory = (void *)ne_fs_isDirectory,
+        .makeDirectory = NULL,
+        .list = (void *)ne_fs_list,
+        .open = (void *)ne_fs_open,
+        .close = (void *)ne_fs_close,
+        .write = (void *)ne_fs_write,
+        .read = (void *)ne_fs_read,
+        .seek = NULL,
+    };
+    nn_addFileSystem(computer, "OpenOS", 1, &genericFS);
+
     double lastTime = nn_realTime();
     while(true) {
         double now = nn_realTime();
@@ -116,6 +270,9 @@ int main() {
         }
 
         int state = nn_tickComputer(computer);
+        if(nn_isOverworked(computer)) {
+            printf("Machine overworked.\n");
+        }
         if(state == NN_STATE_SWITCH) {
             nn_architecture *nextArch = nn_getNextArchitecture(computer);
             printf("Next architecture: %s\n", nextArch->archName);
diff --git a/src/sandbox.lua b/src/sandbox.lua
index a8cc488..75b0560 100644
--- a/src/sandbox.lua
+++ b/src/sandbox.lua
@@ -76,7 +76,7 @@ local function checkArg(idx, v, ...)
     local bad = true
     local n = select("#", ...)
     for i=1,n do
-        local t  = select(i, ...)
+        local t = select(i, ...)
         if type(v) == t then bad = false break end
     end
     if not bad then return end
@@ -390,9 +390,11 @@ sandbox = {
     },
 
     utf8 = copy(utf8),
+    unicode = copy(unicode),
     checkArg = checkArg,
     component = libcomponent,
     computer = libcomputer,
+    print = print,
 }
 sandbox._G = sandbox
 
@@ -418,12 +420,10 @@ while true do
     local ok, err = resume(co)
 
     if not ok then
-        error(err)
+        error(debug.traceback(co, err), 0)
     elseif coroutine.status(co) == "dead" then
         error("computer halted", 0)
     else
         coroutine.yield()
     end
 end
-
-error("machine halted")
diff --git a/src/testLuaArch.c b/src/testLuaArch.c
index b4bb9b8..3cde68b 100644
--- a/src/testLuaArch.c
+++ b/src/testLuaArch.c
@@ -19,14 +19,12 @@ void *testLuaArch_alloc(testLuaArch *arch, void *ptr, size_t osize, size_t nsize
         nn_free(ptr);
         return NULL;
     } else {
-        if(arch->memoryUsed - osize + nsize > nn_getComputerMemoryTotal(arch->computer)) {
+        size_t actualOldSize = osize;
+        if(ptr == NULL) actualOldSize = 0;
+        if(arch->memoryUsed - actualOldSize + nsize > nn_getComputerMemoryTotal(arch->computer)) {
             return NULL; // OOM condition
         }
-        if(ptr != NULL) {
-            // if ptr is NULL, osize will actually encode the type.
-            // We do not want that to mess us up.
-            arch->memoryUsed -= osize;
-        }
+        arch->memoryUsed -= actualOldSize;
         arch->memoryUsed += nsize;
         return nn_realloc(ptr, nsize);
     }
@@ -397,8 +395,9 @@ static int testLuaArch_component_invoke(lua_State *L) {
         return 2;
     }
     nn_resetCall(c);
+    printf("%s %s %d\n", addr, method, argc);
     for(size_t i = 0; i < argc; i++) {
-        nn_addArgument(c, testLuaArch_getValue(L, 2 + argc));
+        nn_addArgument(c, testLuaArch_getValue(L, 3 + i));
     }
     if(!nn_invokeComponentMethod(component, method)) {
         nn_resetCall(c);
@@ -500,6 +499,10 @@ void testLuaArch_loadEnv(lua_State *L) {
     lua_pushinteger(L, NN_STATE_SWITCH);
     lua_setfield(L, states, "switch");
     lua_setglobal(L, "states");
+
+    lua_createtable(L, 0, 20);
+    int unicode = lua_gettop(L);
+    lua_setglobal(L, "unicode");
 }
 
 testLuaArch *testLuaArch_setup(nn_computer *computer, void *_) {