diff --git a/src/devices/audio.h b/src/devices/audio.h
index eab4c47..299307f 100644
--- a/src/devices/audio.h
+++ b/src/devices/audio.h
@@ -12,10 +12,9 @@ WITH REGARD TO THIS SOFTWARE.
 
 typedef signed int Sint32;
 
-
 #define AUDIO_VERSION 1
-#define AUDIO_DEIMASK 0x0000
-#define AUDIO_DEOMASK 0x0000
+#define AUDIO_DEIMASK 0x0014
+#define AUDIO_DEOMASK 0x8000
 
 #define SAMPLE_FREQUENCY 44100
 #define POLYPHONY 4
diff --git a/src/devices/console.h b/src/devices/console.h
index 7e10d5b..85d659b 100644
--- a/src/devices/console.h
+++ b/src/devices/console.h
@@ -11,7 +11,7 @@ WITH REGARD TO THIS SOFTWARE.
 
 #define CONSOLE_VERSION 1
 #define CONSOLE_DEIMASK 0x0000
-#define CONSOLE_DEOMASK 0x0000
+#define CONSOLE_DEOMASK 0x0300
 
 #define CONSOLE_STD 0x1
 #define CONSOLE_ARG 0x2
diff --git a/src/devices/datetime.h b/src/devices/datetime.h
index c01f70f..f74c0a0 100644
--- a/src/devices/datetime.h
+++ b/src/devices/datetime.h
@@ -10,7 +10,7 @@ WITH REGARD TO THIS SOFTWARE.
 */
 
 #define DATETIME_VERSION 1
-#define DATETIME_DEIMASK 0x0000
+#define DATETIME_DEIMASK 0x07ff
 #define DATETIME_DEOMASK 0x0000
 
 Uint8 datetime_dei(Uxn *u, Uint8 addr);
diff --git a/src/devices/file.h b/src/devices/file.h
index 7bdb6a0..b29b482 100644
--- a/src/devices/file.h
+++ b/src/devices/file.h
@@ -11,7 +11,7 @@ WITH REGARD TO THIS SOFTWARE.
 
 #define FILE_VERSION 1
 #define FILE_DEIMASK 0x0000
-#define FILE_DEOMASK 0x0000
+#define FILE_DEOMASK 0xa260
 
 #define POLYFILEY 2
 #define DEV_FILE0 0xa
diff --git a/src/devices/mouse.h b/src/devices/mouse.h
index d422f92..e848e7b 100644
--- a/src/devices/mouse.h
+++ b/src/devices/mouse.h
@@ -9,7 +9,6 @@ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 WITH REGARD TO THIS SOFTWARE.
 */
 
-
 #define MOUSE_VERSION 1
 #define MOUSE_DEIMASK 0x0000
 #define MOUSE_DEOMASK 0x0000
diff --git a/src/devices/screen.h b/src/devices/screen.h
index e392e5e..d1e0dbc 100644
--- a/src/devices/screen.h
+++ b/src/devices/screen.h
@@ -11,8 +11,8 @@ WITH REGARD TO THIS SOFTWARE.
 */
 
 #define SCREEN_VERSION 1
-#define SCREEN_DEIMASK 0x0000
-#define SCREEN_DEOMASK 0x0000
+#define SCREEN_DEIMASK 0x003c
+#define SCREEN_DEOMASK 0xc028
 
 typedef struct UxnScreen {
 	int width, height, x1, y1, x2, y2;
diff --git a/src/devices/system.c b/src/devices/system.c
index 82e09a9..28aef3d 100644
--- a/src/devices/system.c
+++ b/src/devices/system.c
@@ -74,6 +74,15 @@ system_inspect(Uxn *u)
 	system_print(&u->rst, "rst");
 }
 
+void
+system_connect(Uint8 device, Uint8 ver, Uint16 dei, Uint16 deo)
+{
+	/* printf("%02x -> v%d %04x %04x\n", device, ver, dei, deo); */
+	dev_vers[device] = ver;
+	dei_mask[device] = dei;
+	deo_mask[device] = deo;
+}
+
 /* IO */
 
 void
diff --git a/src/devices/system.h b/src/devices/system.h
index a4efdce..6526b19 100644
--- a/src/devices/system.h
+++ b/src/devices/system.h
@@ -11,10 +11,11 @@ WITH REGARD TO THIS SOFTWARE.
 
 #define SYSTEM_VERSION 1
 #define SYSTEM_DEIMASK 0x0000
-#define SYSTEM_DEOMASK 0x0000
+#define SYSTEM_DEOMASK 0xff28
 
 #define RAM_PAGES 0x10
 
+void system_connect(Uint8 device, Uint8 ver, Uint16 dei, Uint16 deo);
 int system_load(Uxn *u, char *filename);
 void system_inspect(Uxn *u);
 int system_error(char *msg, const char *err);
diff --git a/src/uxn.c b/src/uxn.c
index 18e4ba3..e7f8bf8 100644
--- a/src/uxn.c
+++ b/src/uxn.c
@@ -95,4 +95,5 @@ uxn_boot(Uxn *u, Uint8 *ram)
 		cptr[i] = 0;
 	u->ram = ram;
 	return 1;
+
 }
diff --git a/src/uxn.h b/src/uxn.h
index 8bb5831..fda0086 100644
--- a/src/uxn.h
+++ b/src/uxn.h
@@ -42,8 +42,7 @@ typedef struct Uxn {
 extern Uint8 emu_dei(Uxn *u, Uint8 addr);
 extern void emu_deo(Uxn *u, Uint8 addr);
 extern int emu_halt(Uxn *u, Uint8 instr, Uint8 err, Uint16 addr);
-extern Uint16 dei_mask[];
-extern Uint16 deo_mask[];
+extern Uint16 dev_vers[0x10], dei_mask[0x10], deo_mask[0x10];
 
 /* built-ins */
 
diff --git a/src/uxncli.c b/src/uxncli.c
index 3250a78..3e3f68b 100644
--- a/src/uxncli.c
+++ b/src/uxncli.c
@@ -18,8 +18,7 @@ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 WITH REGARD TO THIS SOFTWARE.
 */
 
-Uint16 deo_mask[] = {0xc028, 0x0300, 0xc028, 0x8000, 0x8000, 0x8000, 0x8000, 0x0000, 0x0000, 0x0000, 0xa260, 0xa260, 0x0000, 0x0000, 0x0000, 0x0000};
-Uint16 dei_mask[] = {0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x07ff, 0x0000, 0x0000, 0x0000};
+Uint16 dev_vers[0x10], dei_mask[0x10], deo_mask[0x10];
 
 Uint8
 emu_dei(Uxn *u, Uint8 addr)
@@ -53,6 +52,12 @@ main(int argc, char **argv)
 		return system_error("Boot", "Failed");
 	if(!system_load(&u, argv[i++]))
 		return system_error("Load", "Failed");
+	/* connect devices */
+	system_connect(0x0, SYSTEM_VERSION, SYSTEM_DEIMASK, SYSTEM_DEOMASK);
+	system_connect(0x1, CONSOLE_VERSION, CONSOLE_DEIMASK, CONSOLE_DEOMASK);
+	system_connect(0xa, FILE_VERSION, FILE_DEIMASK, FILE_DEOMASK);
+	system_connect(0xb, FILE_VERSION, FILE_DEIMASK, FILE_DEOMASK);
+	system_connect(0xc, DATETIME_VERSION, DATETIME_DEIMASK, DATETIME_DEOMASK);
 	u.dev[0x17] = argc - i;
 	if(uxn_eval(&u, PAGE_PROGRAM)) {
 		for(; i < argc; i++) {
diff --git a/src/uxnemu.c b/src/uxnemu.c
index 7ad5b9b..9e9071e 100644
--- a/src/uxnemu.c
+++ b/src/uxnemu.c
@@ -60,8 +60,7 @@ static Uint32 stdin_event, audio0_event, zoom = 1;
 static Uint64 exec_deadline, deadline_interval, ms_interval;
 static char *rom_path;
 
-Uint16 deo_mask[] = {0xff28, 0x0300, 0xc028, 0x8000, 0x8000, 0x8000, 0x8000, 0x0000, 0x0000, 0x0000, 0xa260, 0xa260, 0x0000, 0x0000, 0x0000, 0x0000};
-Uint16 dei_mask[] = {0x0000, 0x0000, 0x003c, 0x0014, 0x0014, 0x0014, 0x0014, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x07ff, 0x0000, 0x0000, 0x0000};
+Uint16 dev_vers[0x10], dei_mask[0x10], deo_mask[0x10];
 
 static int
 clamp(int v, int min, int max)
@@ -252,6 +251,19 @@ emu_init(void)
 	SDL_SetRenderDrawColor(emu_renderer, 0x00, 0x00, 0x00, 0xff);
 	ms_interval = SDL_GetPerformanceFrequency() / 1000;
 	deadline_interval = ms_interval * TIMEOUT_MS;
+	/* connect devices */
+	system_connect(0x0, SYSTEM_VERSION, SYSTEM_DEIMASK, SYSTEM_DEOMASK);
+	system_connect(0x1, CONSOLE_VERSION, CONSOLE_DEIMASK, CONSOLE_DEOMASK);
+	system_connect(0x2, SCREEN_VERSION, SCREEN_DEIMASK, SCREEN_DEOMASK);
+	system_connect(0x3, AUDIO_VERSION, AUDIO_DEIMASK, AUDIO_DEOMASK);
+	system_connect(0x4, AUDIO_VERSION, AUDIO_DEIMASK, AUDIO_DEOMASK);
+	system_connect(0x5, AUDIO_VERSION, AUDIO_DEIMASK, AUDIO_DEOMASK);
+	system_connect(0x6, AUDIO_VERSION, AUDIO_DEIMASK, AUDIO_DEOMASK);
+	system_connect(0x8, CONTROL_VERSION, CONTROL_DEIMASK, CONTROL_DEOMASK);
+	system_connect(0x9, MOUSE_VERSION, MOUSE_DEIMASK, MOUSE_DEOMASK);
+	system_connect(0xa, FILE_VERSION, FILE_DEIMASK, FILE_DEOMASK);
+	system_connect(0xb, FILE_VERSION, FILE_DEIMASK, FILE_DEOMASK);
+	system_connect(0xc, DATETIME_VERSION, DATETIME_DEIMASK, DATETIME_DEOMASK);
 	return 1;
 }