diff --git a/src/components/hologram.c b/src/components/hologram.c
index 599c284..65f087b 100644
--- a/src/components/hologram.c
+++ b/src/components/hologram.c
@@ -1,6 +1,13 @@
 #include "hologram.h"
 
-void nn_hologram_clear() {
+// safety:
+// For valid indexes to be valid,
+// stuff must be from 0 to limit - 1
+nn_size_t nn_positionToIndex(nn_hologram *h, unsigned x, unsigned y, unsigned z) {
+	return x + y * h->width_x + z * h->width_x * h->height;
+}
+
+void nn_hologram_clear(nn_hologram *h) {
 	
 }
 
diff --git a/src/emulator.c b/src/emulator.c
index f9a6bc6..baa9e5a 100644
--- a/src/emulator.c
+++ b/src/emulator.c
@@ -618,7 +618,7 @@ void ne_log(void *_, void *__, nn_component *component, nn_computer *computer) {
 	}
 }
 
-int main() {
+int main(int argc, char **argv) {
     printf("Setting up universe\n");
     nn_Context ctx = nn_libcContext();
     nn_Alloc alloc = ctx.allocator;
@@ -665,7 +665,7 @@ int main() {
 
     nn_addEEPROM(computer, NULL, 0, genericEEPROM);
 
-    nn_address fsFolder = "OpenOS";
+    nn_address fsFolder = argc > 1 ? argv[1] : "OpenOS";
     nn_filesystemTable genericFSTable = {
         .userdata = fsFolder,
         .deinit = NULL,
diff --git a/src/neonucleus.h b/src/neonucleus.h
index 4bc28a6..351ee3f 100644
--- a/src/neonucleus.h
+++ b/src/neonucleus.h
@@ -1056,8 +1056,6 @@ nn_bool_t nn_destroyHologram(nn_hologram *hologram);
 
 nn_component *nn_addHologram(nn_computer *computer, nn_address address, int slot, nn_hologram *hologram);
 
-int nn_XYZtoIndex(int x, int y, int z);
-
 void nn_hologram_clear(nn_hologram *hologram);
 int nn_hologram_get(nn_hologram *hologram, int x, int y, int z);
 void nn_hologram_set(nn_hologram *hologram, int x, int y, int z, int value);