diff --git a/src/mess/machine/thomson.c b/src/mess/machine/thomson.c
index 7e32d7c7233..3afd1ba296f 100644
--- a/src/mess/machine/thomson.c
+++ b/src/mess/machine/thomson.c
@@ -4114,16 +4114,20 @@ MACHINE_START_MEMBER( thomson_state, to8 )
 	{
 		membank( THOM_CART_BANK )->configure_entries( 8,    16, ram, 0x4000 );
 		membank( THOM_CART_BANK )->configure_entries( 8+16, 16, ram, 0x4000 );
+		membank( TO8_DATA_LO )->configure_entries( 0, 16, ram + 0x2000, 0x4000 );
+		membank( TO8_DATA_LO )->configure_entries( 16, 16, ram + 0x2000, 0x4000 );
+		membank( TO8_DATA_HI )->configure_entries( 0, 16, ram + 0x0000, 0x4000 );
+		membank( TO8_DATA_HI )->configure_entries( 16, 16, ram + 0x0000, 0x4000 );
 	}
 	else
 	{
 		membank( THOM_CART_BANK )->configure_entries( 8, 32, ram, 0x4000 );
+		membank( TO8_DATA_LO )->configure_entries( 0, 32, ram + 0x2000, 0x4000 );
+		membank( TO8_DATA_HI )->configure_entries( 0, 32, ram + 0x0000, 0x4000 );
 	}
 	membank( THOM_VRAM_BANK )->configure_entries( 0,  2, ram, 0x2000 );
 	membank( TO8_SYS_LO )->configure_entry( 0,  ram + 0x6000);
 	membank( TO8_SYS_HI )->configure_entry( 0,  ram + 0x4000);
-	membank( TO8_DATA_LO )->configure_entries( 0, 32, ram + 0x2000, 0x4000 );
-	membank( TO8_DATA_HI )->configure_entries( 0, 32, ram + 0x0000, 0x4000 );
 	membank( TO8_BIOS_BANK )->configure_entries( 0,  2, mem + 0x30800, 0x2000 );
 	membank( THOM_CART_BANK )->set_entry( 0 );
 	membank( THOM_VRAM_BANK )->set_entry( 0 );