diff --git a/devices/CMakeLists.txt b/devices/CMakeLists.txt
index 36a654d..c75a73a 100644
--- a/devices/CMakeLists.txt
+++ b/devices/CMakeLists.txt
@@ -6,6 +6,7 @@ file(GLOB SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/*.cpp"
                   "${CMAKE_CURRENT_SOURCE_DIR}/common/*.cpp"
                   "${CMAKE_CURRENT_SOURCE_DIR}/common/adb/*.cpp"
                   "${CMAKE_CURRENT_SOURCE_DIR}/common/i2c/*.cpp"
+                  "${CMAKE_CURRENT_SOURCE_DIR}/common/nubus/*.cpp"
                   "${CMAKE_CURRENT_SOURCE_DIR}/common/pci/*.cpp"
                   "${CMAKE_CURRENT_SOURCE_DIR}/common/scsi/*.cpp"
                   "${CMAKE_CURRENT_SOURCE_DIR}/ethernet/*.cpp"
diff --git a/devices/common/hwcomponent.h b/devices/common/hwcomponent.h
index 6543b1b..50c4d15 100644
--- a/devices/common/hwcomponent.h
+++ b/devices/common/hwcomponent.h
@@ -39,6 +39,8 @@ enum HWCompType {
     I2C_DEV     = 1ULL << 9,  /* I2C device */
     ADB_HOST    = 1ULL << 12, /* ADB host   */
     ADB_DEV     = 1ULL << 13, /* ADB device */
+    PDS_DEV     = 1ULL << 14, /* processor direct slot (PDS) device */
+    NUBUS_DEV   = 1ULL << 15, /* Nubus device */
     INT_CTRL    = 1ULL << 16, /* interrupt controller */
     SCSI_BUS    = 1ULL << 20, /* SCSI bus */
     SCSI_HOST   = 1ULL << 21, /* SCSI host adapter */
diff --git a/devices/common/nubus/nubusutils.cpp b/devices/common/nubus/nubusutils.cpp
new file mode 100644
index 0000000..eca08a7
--- /dev/null
+++ b/devices/common/nubus/nubusutils.cpp
@@ -0,0 +1,146 @@
+/*
+DingusPPC - The Experimental PowerPC Macintosh emulator
+Copyright (C) 2018-22 divingkatae and maximum
+                      (theweirdo)     spatium
+
+(Contact divingkatae#1017 or powermax#2286 on Discord for more info)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#include <devices/common/nubus/nubusutils.h>
+#include <devices/memctrl/memctrlbase.h>
+#include <machines/machinebase.h>
+#include <loguru.hpp>
+#include "memaccess.h"
+
+#include <cinttypes>
+#include <fstream>
+
+uint32_t calculate_rom_crc(uint8_t *data_ptr, int length)
+{
+    uint32_t sum = 0;
+
+    for (int i = 0; i < length; i++) {
+        // rotate sum left by one bit
+        if (sum & 0x80000000UL) {
+            sum = (sum << 1) | 1;
+        } else {
+            sum = (sum << 1) | 0;
+        }
+        sum += data_ptr[i];
+    }
+
+    return sum;
+}
+
+int load_declaration_rom(const std::string rom_path, int slot_num)
+{
+    std::ifstream rom_file;
+
+    int result = 0;
+
+    try {
+        rom_file.open(rom_path, std::ios::in | std::ios::binary);
+        if (rom_file.fail()) {
+            throw std::runtime_error("could not open declaration ROM image");
+        }
+
+        // determine image size
+        rom_file.seekg(0, std::ios::end);
+        uint32_t rom_size = rom_file.tellg();
+
+        // load it
+        auto rom_data = std::unique_ptr<uint8_t[]> (new uint8_t[rom_size]);
+        rom_file.seekg(0, std::ios::beg);
+        rom_file.read((char *)rom_data.get(), rom_size);
+
+        // verify image data
+        uint8_t byte_lane = rom_data[rom_size - 1];
+        if ((byte_lane & 0xF) != ((byte_lane >> 4) ^ 0xF)) {
+            throw std::runtime_error("invalid byte lane value");
+        }
+
+        if (READ_DWORD_BE_A(&rom_data[rom_size - 6]) != 0x5A932BC7UL) {
+            throw std::runtime_error("invalid test pattern");
+        }
+
+        if (rom_data[rom_size - 7] != 1) {
+            throw std::runtime_error("unsupported format");
+        }
+
+        uint32_t crc   = READ_DWORD_BE_A(&rom_data[rom_size - 12]);
+        int hdr_length = READ_DWORD_BE_A(&rom_data[rom_size - 16]);
+
+        // patch the CRC field of the format header to 0
+        WRITE_DWORD_BE_A(&rom_data[rom_size - 12], 0);
+
+        uint32_t test_crc = calculate_rom_crc(rom_data.get(), hdr_length);
+
+        // restore the CRC field value
+        WRITE_DWORD_BE_A(&rom_data[rom_size - 12], crc);
+
+        if (test_crc != crc) {
+            throw std::runtime_error("invalid CRC");
+        }
+
+        int lanes_used = 0;
+
+        // count meaningful lanes in a data quad
+        for (int i = 0; i < 4; i++) {
+            if (byte_lane & (1 << i)) {
+                lanes_used++;
+            }
+        }
+
+        // calculate padded size = rom_size * (4 / lanes_used)
+        int padded_len = static_cast<int>((float)rom_size * (4 / (float)lanes_used) + 0.5f);
+
+        // calculate starting physical address of the ROM
+        uint32_t rom_phys_start = (0xF0FFFFFFUL | ((slot_num & 0xF) << 24)) - padded_len + 1;
+
+        auto mem_crtl = dynamic_cast<MemCtrlBase*>(gMachineObj->get_comp_by_type(HWCompType::MEM_CTRL));
+        if (!mem_crtl->add_rom_region(rom_phys_start, padded_len)) {
+            throw std::runtime_error("could not allocate ROM space");
+        }
+
+        int data_pos = 0;
+
+        auto new_data = std::unique_ptr<uint8_t[]> (new uint8_t[padded_len]);
+
+        // prepare new ROM data by copying over used lanes
+        // and padding unused lanes with 0xFF
+        // NOTE: speed uncritical - don't optimize!
+        for (int i = 0; i < padded_len; i += 4) {
+            for (int b = 0; b < 4; b++) {
+                if (byte_lane & (1 << b)) {
+                    new_data[i+b] = rom_data[data_pos++];
+                } else {
+                    new_data[i+b] = 0xFF;
+                }
+            }
+        }
+
+        // move padded ROM data to the memory region
+        mem_crtl->set_data(rom_phys_start, new_data.get(), padded_len);
+    }
+    catch (const std::exception& exc) {
+        LOG_F(ERROR, "load_declaration_rom failed: %s", exc.what());
+        result = -1;
+    }
+
+    rom_file.close();
+
+    return result;
+}
diff --git a/devices/common/nubus/nubusutils.h b/devices/common/nubus/nubusutils.h
new file mode 100644
index 0000000..bcee4a5
--- /dev/null
+++ b/devices/common/nubus/nubusutils.h
@@ -0,0 +1,30 @@
+/*
+DingusPPC - The Experimental PowerPC Macintosh emulator
+Copyright (C) 2018-22 divingkatae and maximum
+                      (theweirdo)     spatium
+
+(Contact divingkatae#1017 or powermax#2286 on Discord for more info)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#ifndef NUBUS_UTILS_H
+#define NUBUS_UTILS_H
+
+#include <cinttypes>
+#include <string>
+
+int load_declaration_rom(const std::string rom_path, int slot_num);
+
+#endif // NUBUS_UTILS_H