diff --git a/src/system/boot/platform/atari_m68k/toscalls.S b/src/system/boot/platform/atari_m68k/toscalls.S
index 246f180735..8bc67cf8fa 100644
--- a/src/system/boot/platform/atari_m68k/toscalls.S
+++ b/src/system/boot/platform/atari_m68k/toscalls.S
@@ -19,7 +19,7 @@ _trap_ret_addr:
 /*	uint32 bios(uint16 nr, ...); */
 FUNCTION(bios):
 	move.l	(%a7)+,_trap_ret_addr
-	trap	#
+	trap	#13
 	move.l	_trap_ret_addr,-(%a7)
 	rts
 
diff --git a/src/system/boot/platform/atari_m68k/toscalls.h b/src/system/boot/platform/atari_m68k/toscalls.h
index 5df4e35795..e5b1062b90 100644
--- a/src/system/boot/platform/atari_m68k/toscalls.h
+++ b/src/system/boot/platform/atari_m68k/toscalls.h
@@ -13,23 +13,97 @@
 extern "C" {
 #endif
 
+#define DEV_PRINTER	0
+#define DEV_AUX	1
+#define DEV_CON	2
+#define DEV_MIDI	3
+#define DEV_IKBD	4
+#define DEV_RAW	5
+
 /* 
  * Atari BIOS calls
  */
 
 extern int32 bios(uint16 nr, ...);
 
-#define Bconin(p0) bios(2, p0)
-//XXX nparams ?
-#define Kbshift(p0) bios(11, p0)
+// cf. http://www.fortunecity.com/skyscraper/apple/308/html/bios.htm
+
+struct tosbpb {
+	int16 recsiz;
+	int16 clsiz;
+	int16 clsizb;
+	int16 rdlen;
+	int16 fsiz;
+	int16 fatrec;
+	int16 datrec;
+	int16 numcl;
+	int16 bflags;
+};
+
+#define K_RSHIFT	0x01
+#define K_LSHIFT	0x02
+#define K_CTRL	0x04
+#define K_ALT	0x08
+#define K_CAPSLOCK	0x10
+#define K_CLRHOME	0x20
+#define K_INSERT	0x40
+
+#define RW_READ			0x00
+#define RW_READ			0x01
+#define RW_NOMEDIACH	0x02
+#define RW_NORETRY		0x04
+#define RW_NOTRANSLATE	0x08
+
+//#define Getmpb() bios(0)
+#define Bconstat(dev) bios(1, (uint16)dev)
+#define Bconin(dev) bios(2, (uint16)dev)
+#define Bconout(dev, chr) bios(3, (uint16)dev, (uint16)chr)
+#define Rwabs(mode, buf, count, recno, dev, lrecno) bios(4, (int16)mode, (void *)buf, (int16)count, (int16)recno, (uint16)dev, (int32)lrecno)
+//#define Setexc() bios(5, )
+#define Tickcal() bios(6)
+#define Getbpb(dev) (struct tosbpb *)bios(7, (uint16)dev)
+#define Bcostat(dev) bios(8, (uint16)dev)
+//#define Mediach() bios(9, )
+#define Drvmap() (uint32)bios(10)
+#define Kbshift(mode) bios(11, (uint16)mode)
 
 /* 
  * Atari XBIOS calls
  */
 
-extern int32 bios(uint16 nr, ...);
+extern int32 xbios(uint16 nr, ...);
 
+#define IM_DISABLE	0
+#define IM_RELATIVE	1
+#define IM_ABSOLUTE	2
+#define IM_KEYCODE	4
 
+#define NVM_READ	0
+#define NVM_WRITE	1
+#define NVM_RESET	2
+
+#define Initmous(mode, param, vec) xbios(0, (int16)mode, (void *)param, (void *)vec)
+#define Physbase() (void *)xbios(2)
+#define Logbase() (void *)xbios(3)
+//#define Getrez() xbios(4)
+#define Setscreen(log, phys, mode) xbios(5, (void *)log, (void *)phys, (int16)mode)
+#define VsetScreen(log, phys, mode, modecode) xbios(5, (void *)log, (void *)phys, (int16)mode)
+//#define Mfpint() xbios(13, )
+#define Rsconf(speed, flow, ucr, rsr, tsr, scr) xbios(15, (int16)speed, (int16)flow, (int16)ucr, (int16)rsr, (int16)tsr, (int16)scr)
+//#define Keytbl(unshift, shift, caps) (KEYTAB *)xbios(16, (char *)unshift, (char *)shift, (char *)caps)
+#define Random() xbios(17)
+#define Gettime() (uint32)xbios(23)
+#define Jdisint(intno) xbios(26, (int16)intno)
+#define Jenabint(intno) xbios(27, (int16)intno)
+#define Supexec(func) xbios(38, (void *)func)
+//#define Puntaes() xbios(39)
+#define DMAread(sect, count, buf, dev) xbios(42, (int32)sect, (int16)count, (void *)buf, (int16)dev)
+#define DMAwrite(sect, count, buf, dev) xbios(43, (int32)sect, (int16)count, (void *)buf, (int16)dev)
+#define NVMaccess(op, start, count, buffer) xbios(46, (int16)op, (int16)start, (int16)count, (char *)buffer)
+#define VsetMode(mode) xbios(88, (int16)mode)
+#define VgetMonitor() xbios(89)
+#define Locksnd() xbios(128)
+#define Unlocksnd() xbios(129)
 
 /* 
  * Atari GEMDOS calls