diff --git a/src/mainboard/asrock/e350m1/mptable.c b/src/mainboard/asrock/e350m1/mptable.c
index 6444be5..b6c5b76 100644
--- a/src/mainboard/asrock/e350m1/mptable.c
+++ b/src/mainboard/asrock/e350m1/mptable.c
@@ -35,6 +35,7 @@ extern u32 apicid_sb800;
 extern u32 bus_type[256];
 extern u32 sbdn_sb800;
 
+// SB800 interrupt routing register values: APIC mode
 u8 intr_data[] = {
   [0x00] = 0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17, /* INTA# - INTH# */
   [0x08] = 0x00,0x00,0x00,0x00,0x1F,0x1F,0x1F,0x1F, /* Misc-nil,0,1,2, INT from Serial irq */
@@ -45,6 +46,16 @@ u8 intr_data[] = {
   0x10,0x11,0x12,0x13
 };
 
+// SB800 interrupt routing register values: PIC mode
+u8 intr_data_pic[] = {
+    0x0B, 0x0A, 0x0B, 0x0A, 0x1F, 0x1F, 0x1F, 0x1F,       // 0x00
+    0x00, 0xF1, 0x00, 0x00, 0x1F, 0x1F, 0x1F, 0x1F,       // 0x08
+    0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F,       // 0x10
+    0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F,       // 0x18
+    0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F,       // 0x20
+    0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F, 0x1F,       // 0x28
+    0x0B, 0x0A, 0x0B, 0x0A, 0x1F, 0x1F, 0x1F, 0x1F};      // 0x30
+
 static void *smp_write_config_table(void *v)
 {
   struct mp_config_table *mc;
@@ -75,6 +86,12 @@ static void *smp_write_config_table(void *v)
     outb(intr_data[byte], 0xC01);
   }
 
+  // progran the SB800 PIC mode interrupt routing register values
+  for (byte = 0x0; byte < sizeof(intr_data_pic); byte ++) {
+    outb(byte, 0xC00);
+    outb(intr_data_pic[byte], 0xC01);
+  }
+
   /* I/O Ints:    Type    Polarity    Trigger     Bus ID   IRQ    APIC ID PIN# */
 #define IO_LOCAL_INT(type, intr, apicid, pin) \
   smp_write_lintsrc(mc, (type), MP_IRQ_TRIGGER_EDGE | MP_IRQ_POLARITY_HIGH, bus_isa, (intr), (apicid), (pin));
@@ -149,6 +166,25 @@ static void *smp_write_config_table(void *v)
   IO_LOCAL_INT(mp_NMI, 0x0, MP_APIC_ALL, 0x1);
   /* There is no extension information... */
 
+  // program interrupt line registers for legacy OS use
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x01, 0)), 0x3C, 0x0B);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x01, 1)), 0x3C, 0x0A);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x04, 0)), 0x3C, 0x0B);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x11, 0)), 0x3C, 0x0A);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x12, 0)), 0x3C, 0x0B);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x12, 2)), 0x3C, 0x0A);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x13, 0)), 0x3C, 0x0B);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x13, 2)), 0x3C, 0x0A);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x14, 1)), 0x3C, 0x0A);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x14, 2)), 0x3C, 0x0B);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x14, 5)), 0x3C, 0x0B);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x16, 0)), 0x3C, 0x0B);
+  pci_write_config32(dev_find_slot(0, PCI_DEVFN(0x16, 2)), 0x3C, 0x0A);
+  pci_write_config32(dev_find_slot(3, PCI_DEVFN(0x00, 0)), 0x3C, 0x0B);
+
+  // program slave PIC edge-level control register
+  outb (0x0C, 0x4D1);
+
   /* Compute the checksums */
   return mptable_finalize(mc);
 }