diff --git a/build.sh b/build.sh
index 28c2576..9cd0c1f 100755
--- a/build.sh
+++ b/build.sh
@@ -22,4 +22,4 @@ fi
 echo "Done."
 
 # echo "Running.."
-# uxnasm etc/repl.tal bin/repl.rom && bin/uxn11 bin/repl.rom
+bin/uxn11 ~/roms/left.rom
diff --git a/src/uxn.c b/src/uxn.c
index 13cdae0..8f4a74d 100644
--- a/src/uxn.c
+++ b/src/uxn.c
@@ -22,9 +22,8 @@ WITH REGARD TO THIS SOFTWARE.
 #define POKE(x, y) { if(bs) { u->ram[(x)] = (y) >> 8; u->ram[(x) + 1] = (y); } else { u->ram[(x)] = y; } }
 #define PEEK16(o, x) { o = (u->ram[(x)] << 8) + u->ram[(x) + 1]; }
 #define PEEK(o, x) { if(bs) { PEEK16(o, x) } else { o = u->ram[(x)]; } }
-#define DEVR(o, d, x) { dev = (d); o = dev->dei(dev, (x) & 0x0f); if(bs) { o = (o << 8) + dev->dei(dev, ((x) + 1) & 0x0f); } }
-#define DEVW8(x, y) { dev->dat[(x) & 0xf] = y; dev->deo(dev, (x) & 0x0f); }
-#define DEVW(d, x, y) { dev = (d); if(bs) { DEVW8((x), (y) >> 8); DEVW8((x) + 1, (y)); } else { DEVW8((x), (y)) } }
+#define DEVR(o, x) { o = u->dei(u, x); if (bs) o = (o << 8) + u->dei(u, ((x) + 1) & 0xFF); }
+#define DEVW(x, y) { if (bs) { u->deo(u, (x), (y) >> 8); u->deo(u, ((x) + 1) & 0xFF, (y)); } else { u->deo(u, x, (y)); } }
 #define WARP(x) { if(bs) pc = (x); else pc += (Sint8)(x); }
 
 int
@@ -78,8 +77,8 @@ uxn_eval(Uxn *u, Uint16 pc)
 		case 0x13: /* STR */ POP8(a) POP(b) c = pc + (Sint8)a; POKE(c, b) break;
 		case 0x14: /* LDA */ POP16(a) PEEK(b, a) PUSH(src, b) break;
 		case 0x15: /* STA */ POP16(a) POP(b) POKE(a, b) break;
-		case 0x16: /* DEI */ POP8(a) DEVR(b, &u->dev[a >> 4], a) PUSH(src, b) break;
-		case 0x17: /* DEO */ POP8(a) POP(b) DEVW(&u->dev[a >> 4], a, b) break;
+		case 0x16: /* DEI */ POP8(a) DEVR(b, a) PUSH(src, b) break;
+		case 0x17: /* DEO */ POP8(a) POP(b) DEVW(a, b) break;
 		/* Arithmetic */
 		case 0x18: /* ADD */ POP(a) POP(b) PUSH(src, b + a) break;
 		case 0x19: /* SUB */ POP(a) POP(b) PUSH(src, b - a) break;
@@ -112,6 +111,7 @@ uxn_boot(Uxn *u, Uint8 *ram)
 	u->ram = ram;
 	u->wst = (Stack*)(ram + 0x10000);
 	u->rst = (Stack*)(ram + 0x10100);
+	u->dev2 = (Uint8*)(ram + 0x10200);
 	return 1;
 }
 
diff --git a/src/uxn.h b/src/uxn.h
index c1c5645..bb41e23 100644
--- a/src/uxn.h
+++ b/src/uxn.h
@@ -37,8 +37,10 @@ typedef struct Device {
 } Device;
 
 typedef struct Uxn {
-	Uint8 *ram;
+	Uint8 *ram, *dev2;
 	Stack *wst, *rst;
+	Uint8 (*dei)(struct Uxn *u, Uint8 address);
+	void (*deo)(struct Uxn *u, Uint8 address, Uint8 value);
 	Device dev[16];
 } Uxn;
 
diff --git a/src/uxn11.c b/src/uxn11.c
index 443df5c..71b7db9 100644
--- a/src/uxn11.c
+++ b/src/uxn11.c
@@ -59,16 +59,32 @@ console_deo(Device *d, Uint8 port)
 }
 
 static Uint8
-nil_dei(Device *d, Uint8 port)
+uxn11_dei(struct Uxn *u, Uint8 addr)
 {
-	return d->dat[port];
+	Uint8 p = addr & 0x0f;
+	Device *d = &u->dev[addr >> 4];
+	switch(addr & 0xf0) {
+	case 0x20: screen_dei(d, p); break;
+	case 0xa0: file_dei(d, p); break;
+	case 0xb0: file_dei(d, p); break;
+	case 0xc0: datetime_dei(d, p); break;
+	}
+	return d->dat[p];
 }
 
 static void
-nil_deo(Device *d, Uint8 port)
+uxn11_deo(Uxn *u, Uint8 addr, Uint8 v)
 {
-	(void)d;
-	(void)port;
+	Uint8 p = addr & 0x0f;
+	Device *d = &u->dev[addr >> 4];
+	d->dat[p] = v;
+	switch(addr & 0xf0) {
+	case 0x00: system_deo(d, p); break;
+	case 0x10: console_deo(d, p); break;
+	case 0x20: screen_deo(d, p); break;
+	case 0xa0: file_deo(d, p); break;
+	case 0xb0: file_deo(d, p); break;
+	}
 }
 
 static void
@@ -160,22 +176,8 @@ start(Uxn *u, char *rom)
 	if(!load_rom(u, rom))
 		return error("Load", "Failed");
 	fprintf(stderr, "Loaded %s\n", rom);
-	/* system   */ uxn_port(u, 0x0, nil_dei, system_deo);
-	/* console  */ uxn_port(u, 0x1, nil_dei, console_deo);
-	/* screen   */ devscreen = uxn_port(u, 0x2, screen_dei, screen_deo);
-	/* empty    */ uxn_port(u, 0x3, nil_dei, nil_deo);
-	/* empty    */ uxn_port(u, 0x4, nil_dei, nil_deo);
-	/* empty    */ uxn_port(u, 0x5, nil_dei, nil_deo);
-	/* empty    */ uxn_port(u, 0x6, nil_dei, nil_deo);
-	/* empty    */ uxn_port(u, 0x7, nil_dei, nil_deo);
-	/* control  */ devctrl = uxn_port(u, 0x8, nil_dei, nil_deo);
-	/* mouse    */ devmouse = uxn_port(u, 0x9, nil_dei, nil_deo);
-	/* file0    */ uxn_port(u, 0xa, file_dei, file_deo);
-	/* file1    */ uxn_port(u, 0xb, file_dei, file_deo);
-	/* datetime */ uxn_port(u, 0xc, datetime_dei, nil_deo);
-	/* empty    */ uxn_port(u, 0xd, nil_dei, nil_deo);
-	/* reserved */ uxn_port(u, 0xe, nil_dei, nil_deo);
-	/* reserved */ uxn_port(u, 0xf, nil_dei, nil_deo);
+	u->dei = uxn11_dei;
+	u->deo = uxn11_deo;
 	screen_resize(&uxn_screen, WIDTH, HEIGHT);
 	if(!uxn_eval(u, PAGE_PROGRAM))
 		return error("Boot", "Failed to start rom.");