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Exception at EIP=0000000002c7dc94 (floppy_image_format_t::generate_track_from_levels(int, int, std::vector<unsigned int, std::allocator<unsigned int> >&, int, floppy_image*)+0x0144): ACCESS VIOLATION
While attempting to read memory at 0000000000000000
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Stack crawl:
  00000000002269e0: 0000000002c7dc94 (floppy_image_format_t::generate_track_from_levels(int, int, std::vector<unsigned int, std::allocator<unsigned int> >&, int, floppy_image*)+0x0144)
  0000000000226bc0: 0000000002c7f4c8 (floppy_image_format_t::build_pc_track_fm(int, int, floppy_image*, int, int, floppy_image_format_t::desc_pc_sector const*,int, int, int, int)+0x1588)
  00000000002284d0: 0000000002c8c80f (imd_format::load(io_generic*, unsigned int, floppy_image*)+0x035f)
  0000000000228560: 00000000024125cb (floppy_image_device::call_load()+0x00cb)
  00000000002285a0: 0000000002b6bb49 (device_image_interface::finish_load()+0x00b9)
  0000000000228670: 0000000002bbd648 (image_manager::postdevice_init()+0x0158)
  00000000002286b0: 0000000002b9c7d3 (driver_device::device_start()+0x00f3)
  00000000002287c0: 0000000002b62873 (device_t::start()+0x04c3)
  0000000000228830: 0000000002be0f77 (running_machine::start_all_devices()+0x0077)
  0000000000228910: 0000000002be6c03 (running_machine::start()+0x09b3)
  0000000000228990: 0000000002be7036 (running_machine::run(bool)+0x0146)
  000000000022f3b0: 000000000182308f (mame_machine_manager::execute()+0x015f)
  000000000022f8b0: 0000000001882131 (cli_frontend::execute(int, char**)+0x0fa1)
  000000000022f920: 00000000018214b5 (emulator_info::start_frontend(emu_options&, osd_interface&, int, char**)+0x0035)
  000000000022fd60: 000000000178174b (utf8_main(int, char**)+0x012b)
  000000000022fe50: 000000000300abcc (wmain+0x018c)
  000000000022ff20: 000000000040140c (__tmainCRTStartup+0x025c)
  000000000022ff50: 000000000040153b (mainCRTStartup+0x001b)
  000000000022ff80: 00000000779f59bd (BaseThreadInitThunk+0x000d)
  000000000022ffd0: 0000000077b2a2e1 (RtlUserThreadStart+0x0021)