diff --git a/src/devices/system.c b/src/devices/system.c
index 344056b..8488056 100644
--- a/src/devices/system.c
+++ b/src/devices/system.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <stdlib.h>
 
 #include "../uxn.h"
 #include "system.h"
@@ -57,14 +58,49 @@ uxn_halt(Uxn *u, Uint8 instr, Uint8 err, Uint16 addr)
 	return 0;
 }
 
+/* MMU */
+
+Uint8 *
+mmu_init(Mmu *m, Uint16 pages)
+{
+	m->length = pages;
+	m->pages = (Uint8 *)calloc(0x10000 * pages, sizeof(Uint8));
+	return m->pages;
+}
+
+void
+mmu_copy(Uint8 *ram, Uint16 length, Uint16 src_page, Uint16 src_addr, Uint16 dst_page, Uint16 dst_addr)
+{
+	Uint16 i;
+	for(i = 0; i < length; i++) {
+		ram[dst_page * 0x10000 + dst_addr + i] = ram[src_page * 0x10000 + src_addr + i];
+	}
+}
+
+void
+mmu_eval(Uint8 *ram, Uint16 addr)
+{
+	Uint16 a = addr;
+	Uint8 o = ram[a++];
+	if(o == 1) {
+		Uint16 length = (ram[a++] << 8) + ram[a++];
+		Uint16 src_page = ((ram[a++] << 8) + ram[a++]) % 16, src_addr = (ram[a++] << 8) + ram[a++];
+		Uint16 dst_page = ((ram[a++] << 8) + ram[a++]) % 16, dst_addr = (ram[a++] << 8) + ram[a];
+		mmu_copy(ram, length, src_page, src_addr, dst_page, dst_addr);
+	}
+}
+
 /* IO */
 
 void
 system_deo(Uxn *u, Uint8 *d, Uint8 port)
 {
+	Uint16 a;
 	switch(port) {
-	case 0x2: u->wst = (Stack *)(u->ram + (d[port] ? (d[port] * 0x100) : 0x10000)); break;
-	case 0x3: u->rst = (Stack *)(u->ram + (d[port] ? (d[port] * 0x100) : 0x10100)); break;
+	case 0x3:
+		PEKDEV(a, 0x2);
+		mmu_eval(u->ram, a);
+		break;
 	case 0xe:
 		if(u->wst->ptr || u->rst->ptr) system_inspect(u);
 		break;
diff --git a/src/devices/system.h b/src/devices/system.h
index 9d8117d..6be1005 100644
--- a/src/devices/system.h
+++ b/src/devices/system.h
@@ -11,3 +11,9 @@ WITH REGARD TO THIS SOFTWARE.
 
 void system_inspect(Uxn *u);
 void system_deo(Uxn *u, Uint8 *d, Uint8 port);
+
+typedef struct {
+	Uint8 length, *pages;
+} Mmu;
+
+Uint8 *mmu_init(Mmu *m, Uint16 pages);
diff --git a/src/uxn.c b/src/uxn.c
index 0d33674..967040d 100644
--- a/src/uxn.c
+++ b/src/uxn.c
@@ -100,9 +100,9 @@ uxn_boot(Uxn *u, Uint8 *ram, Dei *dei, Deo *deo)
 	char *cptr = (char *)u;
 	for(i = 0; i < sizeof(*u); i++)
 		cptr[i] = 0x00;
-	u->wst = (Stack *)(ram + 0x10000);
-	u->rst = (Stack *)(ram + 0x10100);
-	u->dev = (Uint8 *)(ram + 0x10200);
+	u->wst = (Stack *)(ram + 0xf0000);
+	u->rst = (Stack *)(ram + 0xf0100);
+	u->dev = (Uint8 *)(ram + 0xf0200);
 	u->ram = ram;
 	u->dei = dei;
 	u->deo = deo;
diff --git a/src/uxncli.c b/src/uxncli.c
index 02a1c29..94d7935 100644
--- a/src/uxncli.c
+++ b/src/uxncli.c
@@ -78,9 +78,10 @@ main(int argc, char **argv)
 {
 	Uxn u;
 	int i;
+	Mmu mmu;
 	if(argc < 2)
 		return emu_error("Usage", "uxncli game.rom args");
-	if(!uxn_boot(&u, (Uint8 *)calloc(0x10300, sizeof(Uint8)), emu_dei, emu_deo))
+	if(!uxn_boot(&u, mmu_init(&mmu, 16), emu_dei, emu_deo))
 		return emu_error("Boot", "Failed");
 	if(!load_rom(&u, argv[1]))
 		return emu_error("Load", "Failed");
diff --git a/src/uxnemu.c b/src/uxnemu.c
index 36bac08..c4bc7a4 100644
--- a/src/uxnemu.c
+++ b/src/uxnemu.c
@@ -53,6 +53,7 @@ static Uint32 stdin_event, audio0_event;
 static Uint64 exec_deadline, deadline_interval, ms_interval;
 
 char *rom_path;
+Mmu mmu;
 
 static int
 error(char *msg, const char *err)
@@ -262,8 +263,8 @@ init(void)
 static int
 start(Uxn *u, char *rom)
 {
-	free(u->ram);
-	if(!uxn_boot(u, (Uint8 *)calloc(0x10300, sizeof(Uint8)), emu_dei, emu_deo))
+	free(mmu.pages);
+	if(!uxn_boot(u, mmu_init(&mmu, 16), emu_dei, emu_deo))
 		return error("Boot", "Failed to start uxn.");
 	if(!load_rom(u, rom))
 		return error("Boot", "Failed to load rom.");
@@ -453,7 +454,8 @@ run(Uxn *u)
 		} else
 			SDL_WaitEvent(NULL);
 	}
-	return error("SDL_WaitEvent", SDL_GetError());;
+	return error("SDL_WaitEvent", SDL_GetError());
+	;
 }
 
 int
@@ -462,11 +464,9 @@ main(int argc, char **argv)
 	SDL_DisplayMode DM;
 	Uxn u = {0};
 	int i, loaded = 0;
-
 	if(!init())
 		return error("Init", "Failed to initialize emulator.");
 	screen_resize(&uxn_screen, WIDTH, HEIGHT);
-
 	/* set default zoom */
 	if(SDL_GetCurrentDisplayMode(0, &DM) == 0)
 		set_zoom(DM.w / 1280);
diff --git a/test.tal b/test.tal
new file mode 100644
index 0000000..638c918
--- /dev/null
+++ b/test.tal
@@ -0,0 +1,28 @@
+
+|0100
+
+	;mmu-write #02 DEO2
+	;mmu-read #02 DEO2
+	;mmu-read2 #02 DEO2
+	#0200 pstr #0a18 DEO
+	#010e DEO
+	#010f DEO
+
+BRK
+
+@pstr ( str* -- )
+
+	&w
+		LDAk #18 DEO
+		INC2 LDAk ,&w JCN
+	POP2
+
+JMP2r
+
+@mmu-write 01 0100 0000 =hello 0001 0800
+@mmu-read 01 0100 0001 0800 0000 0200
+@mmu-read2 01 0100 0001 0800 0000 0205
+
+@hello "hello $1
+
+