diff --git a/src/devices/bus/lpci/i82439tx.cpp b/src/devices/bus/lpci/i82439tx.cpp
index b4bebc8e233..39750f7cd7f 100644
--- a/src/devices/bus/lpci/i82439tx.cpp
+++ b/src/devices/bus/lpci/i82439tx.cpp
@@ -88,6 +88,10 @@ uint32_t i82439tx_device::pci_read(pci_bus_device *pcibus, int function, int off
 		case 0x44:  /* reserved */
 		case 0x48:  /* reserved */
 		case 0x4C:  /* reserved */
+			logerror("i82439tx_pci_read(): Unemulated PCI read 0x%02X, returning 0\n", offset);
+			result = 0;
+			break;
+
 		case 0x50:
 		case 0x54:
 		case 0x58:
@@ -167,12 +171,47 @@ void i82439tx_device::pci_write(pci_bus_device *pcibus, int function, int offset
 			/* read only */
 			break;
 
+		case 0x58:
+			if ((mem_mask & 0x0000f000))
+				i82439tx_configure_memory(data >> 12, 0xf0000, 0xfffff);
+			if ((mem_mask & 0x000f0000))
+				i82439tx_configure_memory(data >> 16, 0xc0000, 0xc3fff);
+			if ((mem_mask & 0x00f00000))
+				i82439tx_configure_memory(data >> 20, 0xc4000, 0xc7fff);
+			if ((mem_mask & 0x0f000000))
+				i82439tx_configure_memory(data >> 24, 0xc8000, 0xccfff);
+			if ((mem_mask & 0xf0000000))
+				i82439tx_configure_memory(data >> 28, 0xcc000, 0xcffff);
+			COMBINE_DATA(&m_regs[(offset - 0x50) / 4]);
+			break;
+
+		case 0x5C:
+			if ((mem_mask & 0x0000000f))
+				i82439tx_configure_memory(data >> 0, 0xd0000, 0xd3fff);
+			if ((mem_mask & 0x000000f0))
+				i82439tx_configure_memory(data >> 4, 0xd4000, 0xd7fff);
+			if ((mem_mask & 0x00000f00))
+				i82439tx_configure_memory(data >> 8, 0xd8000, 0xdbfff);
+			if ((mem_mask & 0x0000f000))
+				i82439tx_configure_memory(data >> 12, 0xdc000, 0xdffff);
+			if ((mem_mask & 0x000f0000))
+				i82439tx_configure_memory(data >> 16, 0xe0000, 0xe3fff);
+			if ((mem_mask & 0x00f00000))
+				i82439tx_configure_memory(data >> 20, 0xe4000, 0xe7fff);
+			if ((mem_mask & 0x0f000000))
+				i82439tx_configure_memory(data >> 24, 0xe8000, 0xecfff);
+			if ((mem_mask & 0xf0000000))
+				i82439tx_configure_memory(data >> 28, 0xec000, 0xeffff);
+			COMBINE_DATA(&m_regs[(offset - 0x50) / 4]);
+			break;
+
 		case 0x04:  /* PCI command register */
 		case 0x0C:
+			logerror("i82439tx_pci_write(): Unemulated PCI write 0x%02X = 0x%04X\n", offset, data);
+			break;
+
 		case 0x50:
 		case 0x54:
-		case 0x58:
-		case 0x5C:
 		case 0x60:
 		case 0x64:
 		case 0x68:
@@ -213,41 +252,6 @@ void i82439tx_device::pci_write(pci_bus_device *pcibus, int function, int offset
 		case 0xF4:
 		case 0xF8:
 		case 0xFC:
-			switch(offset)
-			{
-				case 0x58:
-					if ((mem_mask & 0x0000f000))
-						i82439tx_configure_memory(data >> 12, 0xf0000, 0xfffff);
-					if ((mem_mask & 0x000f0000))
-						i82439tx_configure_memory(data >> 16, 0xc0000, 0xc3fff);
-					if ((mem_mask & 0x00f00000))
-						i82439tx_configure_memory(data >> 20, 0xc4000, 0xc7fff);
-					if ((mem_mask & 0x0f000000))
-						i82439tx_configure_memory(data >> 24, 0xc8000, 0xccfff);
-					if ((mem_mask & 0xf0000000))
-						i82439tx_configure_memory(data >> 28, 0xcc000, 0xcffff);
-					break;
-
-				case 0x5C:
-					if ((mem_mask & 0x0000000f))
-						i82439tx_configure_memory(data >>  0, 0xd0000, 0xd3fff);
-					if ((mem_mask & 0x000000f0))
-						i82439tx_configure_memory(data >>  4, 0xd4000, 0xd7fff);
-					if ((mem_mask & 0x00000f00))
-						i82439tx_configure_memory(data >>  8, 0xd8000, 0xdbfff);
-					if ((mem_mask & 0x0000f000))
-						i82439tx_configure_memory(data >> 12, 0xdc000, 0xdffff);
-					if ((mem_mask & 0x000f0000))
-						i82439tx_configure_memory(data >> 16, 0xe0000, 0xe3fff);
-					if ((mem_mask & 0x00f00000))
-						i82439tx_configure_memory(data >> 20, 0xe4000, 0xe7fff);
-					if ((mem_mask & 0x0f000000))
-						i82439tx_configure_memory(data >> 24, 0xe8000, 0xecfff);
-					if ((mem_mask & 0xf0000000))
-						i82439tx_configure_memory(data >> 28, 0xec000, 0xeffff);
-					break;
-			}
-
 			assert(((offset - 0x50) / 4) >= 0 && ((offset - 0x50) / 4) < ARRAY_LENGTH(m_regs));
 			COMBINE_DATA(&m_regs[(offset - 0x50) / 4]);
 			break;