diff --git a/src/qt/CMakeLists.txt b/src/qt/CMakeLists.txt
index b1f37c4dc..f87a76fcc 100644
--- a/src/qt/CMakeLists.txt
+++ b/src/qt/CMakeLists.txt
@@ -71,6 +71,8 @@ add_library(ui STATIC
     qt_settingsotherperipherals.cpp
     qt_settingsotherperipherals.hpp
     qt_settingsotherperipherals.ui
+    qt_settings_bus_tracking.cpp
+    qt_settings_bus_tracking.hpp
 
     qt_deviceconfig.cpp
     qt_deviceconfig.hpp
diff --git a/src/qt/qt_harddrive_common.hpp b/src/qt/qt_harddrive_common.hpp
index 0e0164d54..5d4bbc9e0 100644
--- a/src/qt/qt_harddrive_common.hpp
+++ b/src/qt/qt_harddrive_common.hpp
@@ -4,10 +4,12 @@
 
 class QString;
 class QAbstractItemModel;
+class SettingsBusTracking;
 
 namespace Harddrives {
     void populateBuses(QAbstractItemModel* model);
     void populateRemovableBuses(QAbstractItemModel* model);
     void populateBusChannels(QAbstractItemModel* model, int bus);
     QString BusChannelName(uint8_t bus, uint8_t channel);
+    inline SettingsBusTracking* busTrackClass = nullptr;
 };
diff --git a/src/qt/qt_settings.cpp b/src/qt/qt_settings.cpp
index 388a843b8..3c8a074db 100644
--- a/src/qt/qt_settings.cpp
+++ b/src/qt/qt_settings.cpp
@@ -14,6 +14,8 @@
 #include "qt_settingsotherperipherals.hpp"
 
 #include "qt_progsettings.hpp"
+#include "qt_harddrive_common.hpp"
+#include "qt_settings_bus_tracking.hpp"
 
 extern "C"
 {
@@ -85,6 +87,7 @@ Settings::Settings(QWidget *parent) :
 
     ui->listView->setModel(new SettingsModel(this));
 
+    Harddrives::busTrackClass = new SettingsBusTracking;
     machine = new SettingsMachine(this);
     display = new SettingsDisplay(this);
     input = new SettingsInput(this);
@@ -124,6 +127,8 @@ Settings::Settings(QWidget *parent) :
 Settings::~Settings()
 {
     delete ui;
+    delete Harddrives::busTrackClass;
+    Harddrives::busTrackClass = nullptr;
 }
 
 void Settings::save() {
diff --git a/src/qt/qt_settings_bus_tracking.cpp b/src/qt/qt_settings_bus_tracking.cpp
new file mode 100644
index 000000000..f6a1c184e
--- /dev/null
+++ b/src/qt/qt_settings_bus_tracking.cpp
@@ -0,0 +1,257 @@
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+#include "86box/hdd.h"
+#include "qt_settings_bus_tracking.hpp"
+
+
+SettingsBusTracking::SettingsBusTracking()
+{
+    int i;
+
+    mfm_tracking = 0x0000000000000000ULL;
+    esdi_tracking = 0x0000000000000000ULL;
+    xta_tracking = 0x0000000000000000ULL;
+
+    for (i = 0; i < 8; i++) {
+        if (i < 4)
+            ide_tracking[i] = 0x0000000000000000ULL;
+
+        scsi_tracking[i] = 0x0000000000000000ULL;
+    }
+}
+
+
+uint8_t
+SettingsBusTracking::next_free_mfm_channel()
+{
+    if ((mfm_tracking & 0xff00ULL) && !(mfm_tracking & 0x00ffULL))
+        return 0;
+
+    if (!(mfm_tracking & 0xff00ULL) && (mfm_tracking & 0x00ffULL))
+        return 1;
+
+    return CHANNEL_NONE;
+}
+
+
+uint8_t
+SettingsBusTracking::next_free_esdi_channel()
+{
+    if ((esdi_tracking & 0xff00ULL) && !(esdi_tracking & 0x00ffULL))
+        return 0;
+
+    if (!(esdi_tracking & 0xff00ULL) && (esdi_tracking & 0x00ffULL))
+        return 1;
+
+    return CHANNEL_NONE;
+}
+
+
+uint8_t
+SettingsBusTracking::next_free_xta_channel()
+{
+    if ((xta_tracking & 0xff00ULL) && !(xta_tracking & 0x00ffULL))
+        return 0;
+
+    if (!(xta_tracking & 0xff00ULL) && (xta_tracking & 0x00ffULL))
+        return 1;
+
+    return CHANNEL_NONE;
+}
+
+
+uint8_t
+SettingsBusTracking::next_free_ide_channel()
+{
+    int i, element;
+    uint64_t mask;
+    uint8_t ret = CHANNEL_NONE;
+
+    for (i = 0; i < 32; i++) {
+        element = ((i << 3) >> 6);
+        mask = 0xffULL << ((uint64_t) ((i << 3) & 0x3f));
+
+        if (ide_tracking[element] & mask) {
+		ret = (uint8_t) i;
+                break;
+        }
+    }
+
+    return ret;
+}
+
+
+uint8_t
+SettingsBusTracking::next_free_scsi_id()
+{
+    int i, element;
+    uint64_t mask;
+    uint8_t ret = CHANNEL_NONE;
+
+    for (i = 0; i < 64; i++) {
+        element = ((i << 3) >> 6);
+        mask = 0xffULL << ((uint64_t) ((i << 3) & 0x3f));
+
+        if (scsi_tracking[element] & mask) {
+		ret = (uint8_t) i;
+                break;
+        }
+    }
+
+    return ret;
+}
+
+
+int
+SettingsBusTracking::mfm_bus_full()
+{
+    int i;
+    uint64_t mask;
+    uint8_t count = 0;
+
+    for (i = 0; i < 2; i++) {
+        mask = 0xffULL << ((uint64_t) ((i << 3) & 0x3f));
+
+        if (mfm_tracking & mask)
+                count++;
+    }
+
+    return (count == 2);
+}
+
+
+int
+SettingsBusTracking::esdi_bus_full()
+{
+    int i;
+    uint64_t mask;
+    uint8_t count = 0;
+
+    for (i = 0; i < 2; i++) {
+        mask = 0xffULL << ((uint64_t) ((i << 3) & 0x3f));
+
+        if (esdi_tracking & mask)
+                count++;
+    }
+
+    return (count == 2);
+}
+
+
+int
+SettingsBusTracking::xta_bus_full()
+{
+    int i;
+    uint64_t mask;
+    uint8_t count = 0;
+
+    for (i = 0; i < 2; i++) {
+        mask = 0xffULL << ((uint64_t) ((i << 3) & 0x3f));
+
+        if (xta_tracking & mask)
+                count++;
+    }
+
+    return (count == 2);
+}
+
+
+int
+SettingsBusTracking::ide_bus_full()
+{
+    int i, element;
+    uint64_t mask;
+    uint8_t count = 0;
+
+    for (i = 0; i < 32; i++) {
+        element = ((i << 3) >> 6);
+        mask = 0xffULL << ((uint64_t) ((i << 3) & 0x3f));
+
+        if (ide_tracking[element] & mask)
+                count++;
+    }
+
+    return (count == 32);
+}
+
+
+int
+SettingsBusTracking::scsi_bus_full()
+{
+    int i, element;
+    uint64_t mask;
+    uint8_t count = 0;
+
+    for (i = 0; i < 64; i++) {
+        element = ((i << 3) >> 6);
+        mask = 0xffULL << ((uint64_t) ((i << 3) & 0x3f));
+
+        if (scsi_tracking[element] & mask)
+                count++;
+    }
+
+    return (count == 64);
+}
+
+
+void
+SettingsBusTracking::device_track(int set, uint8_t dev_type, int bus, int channel)
+{
+    int i, element;
+    uint64_t mask;
+    uint8_t count = 0;
+    fprintf(stderr, "set: %d, dev_type: %hd, bus: %d, channel: %d\n", set, dev_type, bus, channel);
+
+    switch (bus) {
+        case HDD_BUS_MFM:
+            mask = ((uint64_t) dev_type) << ((uint64_t) ((channel << 3) & 0x3f));
+
+            if (set)
+                mfm_tracking |= mask;
+            else
+                mfm_tracking &= ~mask;
+            break;
+
+        case HDD_BUS_ESDI:
+            mask = ((uint64_t) dev_type) << ((uint64_t) ((channel << 3) & 0x3f));
+
+            if (set)
+                esdi_tracking |= mask;
+            else
+                esdi_tracking &= ~mask;
+            break;
+
+        case HDD_BUS_XTA:
+            mask = ((uint64_t) dev_type) << ((uint64_t) ((channel << 3) & 0x3f));
+
+            if (set)
+                xta_tracking |= mask;
+            else
+                xta_tracking &= ~mask;
+            break;
+
+        case HDD_BUS_IDE:
+        case HDD_BUS_ATAPI:
+            element = ((channel << 3) >> 6);
+            mask = ((uint64_t) dev_type) << ((uint64_t) ((channel << 3) & 0x3f));
+
+            if (set)
+                ide_tracking[element] |= mask;
+            else
+                ide_tracking[element] &= ~mask;
+            break;
+
+        case HDD_BUS_SCSI:
+            element = ((channel << 3) >> 6);
+            mask = ((uint64_t) dev_type) << ((uint64_t) ((channel << 3) & 0x3f));
+
+            if (set)
+                scsi_tracking[element] |= mask;
+            else
+                scsi_tracking[element] &= ~mask;
+            break;
+    }
+}
diff --git a/src/qt/qt_settings_bus_tracking.hpp b/src/qt/qt_settings_bus_tracking.hpp
new file mode 100644
index 000000000..614e18d8d
--- /dev/null
+++ b/src/qt/qt_settings_bus_tracking.hpp
@@ -0,0 +1,63 @@
+#ifndef QT_SETTINGS_BUS_TRACKING_HPP
+#define QT_SETTINGS_BUS_TRACKING_HPP
+
+#include <QWidget>
+
+#define TRACK_CLEAR      0
+#define TRACK_SET        1
+
+#define DEV_HDD          0x01
+#define DEV_CDROM        0x02
+#define DEV_ZIP          0x04
+#define DEV_MO           0x08
+
+#define BUS_MFM          0
+#define BUS_ESDI         1
+#define BUS_XTA          2
+#define BUS_IDE          3
+#define BUS_SCSI         4
+
+#define CHANNEL_NONE     0xff
+
+namespace Ui {
+class SettingsBusTracking;
+}
+
+class SettingsBusTracking
+{
+public:
+    explicit SettingsBusTracking();
+    ~SettingsBusTracking() = default;
+
+    /* These return 0xff is none is free. */
+    uint8_t next_free_mfm_channel();
+    uint8_t next_free_esdi_channel();
+    uint8_t next_free_xta_channel();
+    uint8_t next_free_ide_channel();
+    uint8_t next_free_scsi_id();
+
+    int mfm_bus_full();
+    int esdi_bus_full();
+    int xta_bus_full();
+    int ide_bus_full();
+    int scsi_bus_full();
+
+    /* Set: 0 = Clear the device from the tracking, 1 = Set the device on the tracking.
+       Device type: 1 = Hard Disk, 2 = CD-ROM, 4 = ZIP, 8 = Magneto-Optical.
+       Bus: 0 = MFM, 1 = ESDI, 2 = XTA, 3 = IDE, 4 = SCSI. */
+    void device_track(int set, uint8_t dev_type, int bus, int channel);
+
+private:
+    /* 1 channel, 2 devices per channel, 8 bits per device = 16 bits. */
+    uint64_t mfm_tracking;
+    /* 1 channel, 2 devices per channel, 8 bits per device = 16 bits. */
+    uint64_t esdi_tracking;
+    /* 1 channel, 2 devices per channel, 8 bits per device = 16 bits. */
+    uint64_t xta_tracking;
+    /* 16 channels (prepatation for that weird IDE card), 2 devices per channel, 8 bits per device = 256 bits. */
+    uint64_t ide_tracking[4];
+    /* 4 buses, 16 devices per bus, 8 bits per device (future-proofing) = 512 bits. */
+    uint64_t scsi_tracking[8];
+};
+
+#endif // QT_SETTINGS_BUS_TRACKING_HPP
diff --git a/src/qt/qt_settingsharddisks.cpp b/src/qt/qt_settingsharddisks.cpp
index 1e9d11350..9c9afaf14 100644
--- a/src/qt/qt_settingsharddisks.cpp
+++ b/src/qt/qt_settingsharddisks.cpp
@@ -10,6 +10,7 @@ extern "C" {
 
 #include "qt_harddiskdialog.hpp"
 #include "qt_harddrive_common.hpp"
+#include "qt_settings_bus_tracking.hpp"
 #include "qt_progsettings.hpp"
 
 const int ColumnBus         = 0;
@@ -21,6 +22,8 @@ const int ColumnSize        = 5;
 
 const int DataBus           = Qt::UserRole;
 const int DataBusChannel    = Qt::UserRole + 1;
+const int DataBusPrevious   = Qt::UserRole + 2;
+const int DataBusChannelPrevious   = Qt::UserRole + 3;
 
 /*
 static void
@@ -57,7 +60,10 @@ static void addRow(QAbstractItemModel* model, hard_disk_t* hd) {
     model->setData(model->index(row, ColumnBus), busName);
     model->setData(model->index(row, ColumnBus), ProgSettings::loadIcon( "/hard_disk.ico"), Qt::DecorationRole);
     model->setData(model->index(row, ColumnBus), hd->bus, DataBus);
+    model->setData(model->index(row, ColumnBus), hd->bus, DataBusPrevious);
     model->setData(model->index(row, ColumnBus), hd->channel, DataBusChannel);
+    model->setData(model->index(row, ColumnBus), hd->channel, DataBusChannelPrevious);
+    Harddrives::busTrackClass->device_track(1, DEV_HDD, hd->bus, hd->channel);
     QString fileName = hd->fn;
     if (fileName.startsWith(userPath, Qt::CaseInsensitive)) {
         model->setData(model->index(row, ColumnFilename), fileName.mid(userPath.size()));
@@ -132,15 +138,47 @@ void SettingsHarddisks::on_comboBoxBus_currentIndexChanged(int index) {
         return;
     }
 
+    buschangeinprogress = true;
     auto idx = ui->tableView->selectionModel()->currentIndex();
     if (idx.isValid()) {
         auto* model = ui->tableView->model();
         auto col = idx.siblingAtColumn(ColumnBus);
         model->setData(col, ui->comboBoxBus->currentData(Qt::UserRole), DataBus);
         model->setData(col, busChannelName(col), Qt::DisplayRole);
+        Harddrives::busTrackClass->device_track(0, DEV_HDD, model->data(col, DataBusPrevious).toInt(), model->data(col, DataBusChannelPrevious).toInt());
+        model->setData(col, ui->comboBoxBus->currentData(Qt::UserRole), DataBusPrevious);
     }
 
     Harddrives::populateBusChannels(ui->comboBoxChannel->model(), ui->comboBoxBus->currentData().toInt());
+    int chanIdx = 0;
+
+    switch (ui->comboBoxBus->currentData().toInt())
+    {
+        case HDD_BUS_MFM:
+            chanIdx = (Harddrives::busTrackClass->next_free_mfm_channel());
+            break;
+        case HDD_BUS_XTA:
+            chanIdx = (Harddrives::busTrackClass->next_free_xta_channel());
+            break;
+        case HDD_BUS_ESDI:
+            chanIdx = (Harddrives::busTrackClass->next_free_esdi_channel());
+            break;
+        case HDD_BUS_ATAPI:
+        case HDD_BUS_IDE:
+            chanIdx = (Harddrives::busTrackClass->next_free_ide_channel());
+            break;
+        case HDD_BUS_SCSI:
+            chanIdx = (Harddrives::busTrackClass->next_free_scsi_id());
+            break;
+    }
+
+    if (idx.isValid()) {
+        auto* model = ui->tableView->model();
+        auto col = idx.siblingAtColumn(ColumnBus);
+        model->setData(col, chanIdx, DataBusChannelPrevious);
+    }
+    ui->comboBoxChannel->setCurrentIndex(chanIdx);
+    buschangeinprogress = false;
 }
 
 void SettingsHarddisks::on_comboBoxChannel_currentIndexChanged(int index) {
@@ -154,6 +192,9 @@ void SettingsHarddisks::on_comboBoxChannel_currentIndexChanged(int index) {
         auto col = idx.siblingAtColumn(ColumnBus);
         model->setData(col, ui->comboBoxChannel->currentData(Qt::UserRole), DataBusChannel);
         model->setData(col, busChannelName(col), Qt::DisplayRole);
+        if (!buschangeinprogress) Harddrives::busTrackClass->device_track(0, DEV_HDD, model->data(col, DataBus).toInt(), model->data(col, DataBusChannelPrevious).toUInt());
+        Harddrives::busTrackClass->device_track(1, DEV_HDD, model->data(col, DataBus).toInt(), model->data(col, DataBusChannel).toUInt());
+        model->setData(col, ui->comboBoxChannel->currentData(Qt::UserRole), DataBusChannelPrevious);
     }
 }
 
diff --git a/src/qt/qt_settingsharddisks.hpp b/src/qt/qt_settingsharddisks.hpp
index 0289d2ccb..b10e79029 100644
--- a/src/qt/qt_settingsharddisks.hpp
+++ b/src/qt/qt_settingsharddisks.hpp
@@ -30,6 +30,7 @@ private slots:
 
 private:
     Ui::SettingsHarddisks *ui;
+    bool buschangeinprogress = false;
 };
 
 #endif // QT_SETTINGSHARDDISKS_HPP