diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..d95c1c9
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "cores/ZX81/ZX81_MiSTer_zxdos"]
+	path = cores/ZX81/ZX81_MiSTer_zxdos
+	url = https://github.com/avlixa/ZX81_MiSTer_zxdos
diff --git a/cores/ZX81/ZX81_MiSTer_zxdos b/cores/ZX81/ZX81_MiSTer_zxdos
new file mode 160000
index 0000000..3cde11a
--- /dev/null
+++ b/cores/ZX81/ZX81_MiSTer_zxdos
@@ -0,0 +1 @@
+Subproject commit 3cde11a585509b13e5a3458ea477d5aac59d20ff
diff --git a/cores/ZX81/zx81_zxuno_lx9_20211031.ZX1 b/cores/ZX81/zx81_zxuno_lx9_20211031.ZX1
deleted file mode 100644
index df923fd..0000000
Binary files a/cores/ZX81/zx81_zxuno_lx9_20211031.ZX1 and /dev/null differ
diff --git a/cores/ZX81/zx81_zxuno_lx9_20220604.ZX1 b/cores/ZX81/zx81_zxuno_lx9_20220604.ZX1
new file mode 100644
index 0000000..a252bf5
Binary files /dev/null and b/cores/ZX81/zx81_zxuno_lx9_20220604.ZX1 differ