slc1: add note

src/mame/drivers/slc1.cpp

@@ -35,18 +35,22 @@ Keys:
 
 Pasting doesn't work, but if it did...
 
-    Pasting:
+Pasting:
     0-7 : as is
     8-F : H, then 0-7
     + : ^
     - : H^
     ADR : -
 
-    Test Paste:
+Test Paste:
     [[[[[-510011^22^33^44^55^66^77^H8H8^H9H9^-5100
     Now press up-arrow to confirm the data has been entered.
 
-
+TODO:
+    - Make emulation more faithful, io_w doesn't make much sense from
+      a TTL wiring point of view.
+    - Likewise, having 2 auto-switching input mappings is convenient,
+      but not at all how the hardware works.
 
 ***************************************************************************/
 
@@ -207,7 +211,6 @@ void slc1_state::machine_reset()
 
 void slc1_state::mem_map(address_map &map)
 {
-	map.unmap_value_high();
 	map.global_mask(0x4fff);
 	map(0x0000, 0x0fff).rom();
 	map(0x4000, 0x43ff).ram().mirror(0xc00);
@@ -215,7 +218,6 @@ void slc1_state::mem_map(address_map &map)
 
 void slc1_state::io_map(address_map &map)
 {
-	map.unmap_value_high();
 	map(0x0000, 0xffff).rw(FUNC(slc1_state::io_r), FUNC(slc1_state::io_w));
 }