diff --git a/src/mame/drivers/bingo.cpp b/src/mame/drivers/bingo.cpp
index a07858a1045..5bc3a4041b8 100644
--- a/src/mame/drivers/bingo.cpp
+++ b/src/mame/drivers/bingo.cpp
@@ -27,7 +27,7 @@ public:
 
 
 static ADDRESS_MAP_START( bingo_map, AS_PROGRAM, 8, bingo_state )
-	AM_RANGE(0x0000, 0xffff) AM_NOP
+	AM_RANGE(0x0000, 0x7fff) AM_NOP
 	AM_RANGE(0x0000, 0x1eff) AM_ROM
 	AM_RANGE(0x1f00, 0x1fff) AM_RAM
 ADDRESS_MAP_END
diff --git a/src/mame/drivers/blstroid.cpp b/src/mame/drivers/blstroid.cpp
index 636019ec361..3f87c2599d4 100644
--- a/src/mame/drivers/blstroid.cpp
+++ b/src/mame/drivers/blstroid.cpp
@@ -65,25 +65,25 @@ MACHINE_RESET_MEMBER(blstroid_state,blstroid)
 static ADDRESS_MAP_START( main_map, AS_PROGRAM, 16, blstroid_state )
 	ADDRESS_MAP_UNMAP_HIGH
 	ADDRESS_MAP_GLOBAL_MASK(0x83ffff)
-	AM_RANGE(0x000000, 0x03ffff) AM_MIRROR(0x7c0000) AM_ROM
-	AM_RANGE(0x800000, 0x800001) AM_MIRROR(0x7f81fe) AM_DEVWRITE("watchdog", watchdog_timer_device, reset16_w)
-	AM_RANGE(0x800200, 0x800201) AM_MIRROR(0x7f81fe) AM_WRITE(scanline_int_ack_w)
-	AM_RANGE(0x800400, 0x800401) AM_MIRROR(0x7f81fe) AM_WRITE(video_int_ack_w)
-	AM_RANGE(0x800600, 0x800601) AM_MIRROR(0x7f81fe) AM_DEVWRITE("eeprom", atari_eeprom_device, unlock_write)
-	AM_RANGE(0x800800, 0x8009ff) AM_MIRROR(0x7f8000) AM_WRITEONLY AM_SHARE("priorityram")
-	AM_RANGE(0x800a00, 0x800a01) AM_MIRROR(0x7f81fe) AM_DEVWRITE8("jsa", atari_jsa_i_device, main_command_w, 0x00ff)
-	AM_RANGE(0x800c00, 0x800c01) AM_MIRROR(0x7f81fe) AM_DEVWRITE("jsa", atari_jsa_i_device, sound_reset_w)
-	AM_RANGE(0x800e00, 0x800e01) AM_MIRROR(0x7f81fe) AM_WRITE(blstroid_halt_until_hblank_0_w)
-	AM_RANGE(0x801400, 0x801401) AM_MIRROR(0x7f83fe) AM_DEVREAD8("jsa", atari_jsa_i_device, main_response_r, 0x00ff)
-	AM_RANGE(0x801800, 0x801801) AM_MIRROR(0x7f83f8) AM_READ_PORT("DIAL0")
-	AM_RANGE(0x801804, 0x801805) AM_MIRROR(0x7f83f8) AM_READ_PORT("DIAL1")
-	AM_RANGE(0x801c00, 0x801c01) AM_MIRROR(0x7f83fc) AM_READ_PORT("IN0")
-	AM_RANGE(0x801c02, 0x801c03) AM_MIRROR(0x7f83fc) AM_READ_PORT("IN1")
-	AM_RANGE(0x802000, 0x8023ff) AM_MIRROR(0x7f8c00) AM_RAM_DEVWRITE("palette", palette_device, write) AM_SHARE("palette")
-	AM_RANGE(0x803000, 0x8033ff) AM_MIRROR(0x7f8c00) AM_DEVREADWRITE8("eeprom", atari_eeprom_device, read, write, 0x00ff)
-	AM_RANGE(0x804000, 0x804fff) AM_MIRROR(0x7f8000) AM_RAM_DEVWRITE("playfield", tilemap_device, write) AM_SHARE("playfield")
-	AM_RANGE(0x805000, 0x805fff) AM_MIRROR(0x7f8000) AM_RAM AM_SHARE("mob")
-	AM_RANGE(0x806000, 0x807fff) AM_MIRROR(0x7f8000) AM_RAM
+	AM_RANGE(0x000000, 0x03ffff) AM_MIRROR(0x000000) AM_ROM
+	AM_RANGE(0x800000, 0x800001) AM_MIRROR(0x0381fe) AM_DEVWRITE("watchdog", watchdog_timer_device, reset16_w)
+	AM_RANGE(0x800200, 0x800201) AM_MIRROR(0x0381fe) AM_WRITE(scanline_int_ack_w)
+	AM_RANGE(0x800400, 0x800401) AM_MIRROR(0x0381fe) AM_WRITE(video_int_ack_w)
+	AM_RANGE(0x800600, 0x800601) AM_MIRROR(0x0381fe) AM_DEVWRITE("eeprom", atari_eeprom_device, unlock_write)
+	AM_RANGE(0x800800, 0x8009ff) AM_MIRROR(0x038000) AM_WRITEONLY AM_SHARE("priorityram")
+	AM_RANGE(0x800a00, 0x800a01) AM_MIRROR(0x0381fe) AM_DEVWRITE8("jsa", atari_jsa_i_device, main_command_w, 0x00ff)
+	AM_RANGE(0x800c00, 0x800c01) AM_MIRROR(0x0381fe) AM_DEVWRITE("jsa", atari_jsa_i_device, sound_reset_w)
+	AM_RANGE(0x800e00, 0x800e01) AM_MIRROR(0x0381fe) AM_WRITE(blstroid_halt_until_hblank_0_w)
+	AM_RANGE(0x801400, 0x801401) AM_MIRROR(0x0383fe) AM_DEVREAD8("jsa", atari_jsa_i_device, main_response_r, 0x00ff)
+	AM_RANGE(0x801800, 0x801801) AM_MIRROR(0x0383f8) AM_READ_PORT("DIAL0")
+	AM_RANGE(0x801804, 0x801805) AM_MIRROR(0x0383f8) AM_READ_PORT("DIAL1")
+	AM_RANGE(0x801c00, 0x801c01) AM_MIRROR(0x0383fc) AM_READ_PORT("IN0")
+	AM_RANGE(0x801c02, 0x801c03) AM_MIRROR(0x0383fc) AM_READ_PORT("IN1")
+	AM_RANGE(0x802000, 0x8023ff) AM_MIRROR(0x038c00) AM_RAM_DEVWRITE("palette", palette_device, write) AM_SHARE("palette")
+	AM_RANGE(0x803000, 0x8033ff) AM_MIRROR(0x038c00) AM_DEVREADWRITE8("eeprom", atari_eeprom_device, read, write, 0x00ff)
+	AM_RANGE(0x804000, 0x804fff) AM_MIRROR(0x038000) AM_RAM_DEVWRITE("playfield", tilemap_device, write) AM_SHARE("playfield")
+	AM_RANGE(0x805000, 0x805fff) AM_MIRROR(0x038000) AM_RAM AM_SHARE("mob")
+	AM_RANGE(0x806000, 0x807fff) AM_MIRROR(0x038000) AM_RAM
 ADDRESS_MAP_END
 
 
diff --git a/src/mame/machine/6883sam.cpp b/src/mame/machine/6883sam.cpp
index bc9a913f0e6..60c3c980b08 100644
--- a/src/mame/machine/6883sam.cpp
+++ b/src/mame/machine/6883sam.cpp
@@ -510,8 +510,10 @@ void sam6883_device::sam_space<_addrstart, _addrend>::point_specific_bank(const
 		// normalize offset
 		if (mask != 0)
 			offset &= mask;
+		else
+			mask = 0xffff;
 
-		UINT32 mirror = (addrend - addrstart) ^ mask;
+		UINT32 mirror = (addrend - addrstart) & ~mask;
 
 		// this bank is a memory bank - first ensure that we have a bank
 		if (!memory_bank || !memory_bank->matches_exactly(addrstart, addrend) || (mask != m_mask))