diff --git a/devices/ioctrl/grandcentral.cpp b/devices/ioctrl/grandcentral.cpp
index d806865..c8b31d3 100644
--- a/devices/ioctrl/grandcentral.cpp
+++ b/devices/ioctrl/grandcentral.cpp
@@ -22,6 +22,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #include <cpu/ppc/ppcemu.h>
 #include <devices/common/scsi/sc53c94.h>
 #include <devices/ethernet/mace.h>
+#include <devices/floppy/swim3.h>
 #include <devices/ioctrl/macio.h>
 #include <devices/serial/escc.h>
 #include <endianswap.h>
@@ -67,6 +68,9 @@ GrandCentral::GrandCentral() : PCIDevice("mac-io/grandcentral"), InterruptCtrl()
 
     this->scsi_0 = std::unique_ptr<Sc53C94> (new Sc53C94());
     gMachineObj->add_subdevice("Curio_SCSI0", this->scsi_0.get());
+
+    this->swim3 = std::unique_ptr<Swim3::Swim3Ctrl> (new Swim3::Swim3Ctrl());
+    gMachineObj->add_subdevice("SWIM3", this->swim3.get());
 }
 
 void GrandCentral::notify_bar_change(int bar_num)
@@ -103,6 +107,8 @@ uint32_t GrandCentral::read(uint32_t reg_start, uint32_t offset, int size)
             return this->escc->read((offset >> 4) & 0xF);
         case 4: // AWACS
             return this->awacs->snd_ctrl_read(offset & 0xFF, size);
+        case 5: // SWIM3
+            return this->swim3->read((offset >> 4) & 0xF);
         case 6:
         case 7: // VIA-CUDA
             return this->viacuda->read((offset >> 9) & 0xF);
@@ -163,6 +169,9 @@ void GrandCentral::write(uint32_t reg_start, uint32_t offset, uint32_t value, in
         case 4: // AWACS
             this->awacs->snd_ctrl_write(offset & 0xFF, value, size);
             break;
+        case 5:
+            this->swim3->write((offset >> 4) & 0xF, value);
+            break;
         case 6:
         case 7: // VIA-CUDA
             this->viacuda->write((offset >> 9) & 0xF, value);
diff --git a/devices/ioctrl/heathrow.cpp b/devices/ioctrl/heathrow.cpp
index f366ed8..e03cb0d 100644
--- a/devices/ioctrl/heathrow.cpp
+++ b/devices/ioctrl/heathrow.cpp
@@ -76,7 +76,10 @@ HeathrowIC::HeathrowIC() : PCIDevice("mac-io/heathrow"), InterruptCtrl()
 
     this->mesh  = std::unique_ptr<MESHController> (new MESHController(HeathrowMESHID));
     this->escc  = std::unique_ptr<EsccController> (new EsccController());
+
+    // intialize floppy disk HW
     this->swim3 = std::unique_ptr<Swim3::Swim3Ctrl> (new Swim3::Swim3Ctrl());
+    gMachineObj->add_subdevice("SWIM3", this->swim3.get());
 }
 
 void HeathrowIC::notify_bar_change(int bar_num)
@@ -147,7 +150,7 @@ uint32_t HeathrowIC::read(uint32_t reg_start, uint32_t offset, int size) {
         res = this->screamer->snd_ctrl_read(offset - 0x14000, size);
         break;
     case 0x15: // SWIM3
-        return this->swim3->read(offset & 0xF);
+        return this->swim3->read((offset >> 4 )& 0xF);
     case 0x16:
     case 0x17:
         res = this->viacuda->read((offset - 0x16000) >> 9);
@@ -190,8 +193,8 @@ void HeathrowIC::write(uint32_t reg_start, uint32_t offset, uint32_t value, int
     case 0x14:
         this->screamer->snd_ctrl_write(offset - 0x14000, value, size);
         break;
-    case 0x15:
-        this->swim3->write(offset & 0xF, value);
+    case 0x15: // SWIM3
+        this->swim3->write((offset >> 4) & 0xF, value);
         break;
     case 0x16:
     case 0x17:
diff --git a/devices/ioctrl/macio.h b/devices/ioctrl/macio.h
index 3862550..98ee1f8 100644
--- a/devices/ioctrl/macio.h
+++ b/devices/ioctrl/macio.h
@@ -113,12 +113,13 @@ private:
     uint32_t    nvram_addr_hi;
 
     // device cells
-    std::unique_ptr<MaceController> mace;
-    std::unique_ptr<AwacsScreamer>  awacs;   // AWACS audio codec instance
-    std::unique_ptr<ViaCuda>        viacuda; // VIA cell with Cuda MCU attached to it
-    std::unique_ptr<NVram>          nvram;   // NVRAM module
-    std::unique_ptr<EsccController> escc;    // ESCC serial controller
-    std::unique_ptr<Sc53C94>        scsi_0;  // external SCSI
+    std::unique_ptr<MaceController>     mace;
+    std::unique_ptr<AwacsScreamer>      awacs;   // AWACS audio codec instance
+    std::unique_ptr<ViaCuda>            viacuda; // VIA cell with Cuda MCU attached to it
+    std::unique_ptr<NVram>              nvram;   // NVRAM module
+    std::unique_ptr<EsccController>     escc;    // ESCC serial controller
+    std::unique_ptr<Sc53C94>            scsi_0;  // external SCSI
+    std::unique_ptr<Swim3::Swim3Ctrl>   swim3;  // floppy disk controller
 
     std::unique_ptr<DMAChannel>     snd_out_dma;
 };
diff --git a/machines/machinegossamer.cpp b/machines/machinegossamer.cpp
index 0c7d7f0..28c0d89 100644
--- a/machines/machinegossamer.cpp
+++ b/machines/machinegossamer.cpp
@@ -72,7 +72,7 @@ int create_gossamer(std::string& id) {
     MPC106* grackle_obj = dynamic_cast<MPC106*>(gMachineObj->get_comp_by_name("Grackle"));
 
     /* add the machine ID register */
-    gMachineObj->add_component("MachineID", new GossamerID(0x3d8c));
+    gMachineObj->add_component("MachineID", new GossamerID(0xBF3D));
     grackle_obj->add_mmio_region(
         0xFF000004, 4096, dynamic_cast<MMIODevice*>(gMachineObj->get_comp_by_name("MachineID")));