diff --git a/src/add-ons/accelerants/nvidia/engine/nv_globals.c b/src/add-ons/accelerants/nvidia/engine/nv_globals.c
index bf29cbf4a0..af3fb8c8a6 100644
--- a/src/add-ons/accelerants/nvidia/engine/nv_globals.c
+++ b/src/add-ons/accelerants/nvidia/engine/nv_globals.c
@@ -3,7 +3,8 @@
 	This file may be used under the terms of the Be Sample Code License.
 
 	Other authors:
-	Mark Watson
+	Mark Watson,
+	Rudolf Cornelissen 8/2004
 */
 
 #include "nv_std.h"
@@ -24,3 +25,11 @@ nv_get_set_pci nv_pci_access=
 		4,
 		0
 	};
+
+nv_in_out_isa nv_isa_access=
+	{
+		NV_PRIVATE_DATA_MAGIC,
+		0,
+		1,
+		0
+	};
diff --git a/src/add-ons/accelerants/nvidia/engine/nv_globals.h b/src/add-ons/accelerants/nvidia/engine/nv_globals.h
index a91f10dc61..5afab87516 100644
--- a/src/add-ons/accelerants/nvidia/engine/nv_globals.h
+++ b/src/add-ons/accelerants/nvidia/engine/nv_globals.h
@@ -8,6 +8,7 @@ extern area_id my_mode_list_area;
 extern int accelerantIsClone;
 
 extern nv_get_set_pci nv_pci_access;
+extern nv_in_out_isa nv_isa_access;
 
 
 typedef status_t (*crtc_validate_timing)(uint16*, uint16*, uint16*, uint16*, uint16*, uint16*, uint16*, uint16*);
diff --git a/src/add-ons/accelerants/nvidia/engine/nv_info.c b/src/add-ons/accelerants/nvidia/engine/nv_info.c
index f976b0b524..a17389881a 100644
--- a/src/add-ons/accelerants/nvidia/engine/nv_info.c
+++ b/src/add-ons/accelerants/nvidia/engine/nv_info.c
@@ -413,14 +413,12 @@ static status_t exec_type1_script(uint8* rom, uint16 adress, int16* size)
 			adress += 1;
 			LOG(8,("cmd 'RD 8bit ISA I/O REG $%04x, AND-out = $%02x, OR-in = $%02x, WR-bk'\n",
 				reg, and_out, or_in));
-			//fixme? this is for ISA I/O registers. Looks like they are in mapped range
-			//       as well (confirm or update code!)
 			if (exec)
 			{
-				byte = NV_REG8(/*0x00601000 + */reg);
+				byte = ISARB(reg);
 				byte &= (uint8)and_out;
 				byte |= (uint8)or_in;
-				NV_REG8(/*0x00601000 + */reg) = byte;
+				ISAWB(reg, byte);
 			}
 			break;
 		case 0x6e:
@@ -521,17 +519,15 @@ static status_t exec_type1_script(uint8* rom, uint16 adress, int16* size)
 			adress += 1;
 			LOG(8,("cmd 'RD 8bit idx ISA I/O REG $%02x via $%04x, AND-out = $%02x, OR-in = $%02x, WR-bk'\n",
 				index, reg, and_out, or_in));
-			//fixme? this is for ISA I/O registers. Looks like they are in mapped range
-			//       as well (confirm or update code!)
 			if (exec)
 			{
-				safe = NV_REG8(/*0x00601000 + */reg);
-				NV_REG8(/*0x00601000 + */reg) = index;
-				byte = NV_REG8(/*0x00601000 + */reg + 1);
+				safe = ISARB(reg);
+				ISAWB(reg, index);
+				byte = ISARB(reg + 1);
 				byte &= (uint8)and_out;
 				byte |= (uint8)or_in;
-				NV_REG8(/*0x00601000 + */reg + 1) = byte;
-				NV_REG8(/*0x00601000 + */reg) = safe;
+				ISAWB((reg + 1), byte);
+				ISAWB(reg, safe);
 			}
 			break;
 		case 0x79: