This usually means the software can't see the RIB. Double-check your COM port mapping in the DOSBox config file and ensure your radio is powered on. Frequency Out of Range:
mount C C:\GM300 C:
Programming the classic Motorola GM300 mobile radio on Windows 10 is possible, but it requires overcoming a major technical hurdle: the original software (Radio Service Software - RSS) was designed for MS-DOS, not modern 64-bit operating systems. Because the software needs direct hardware access to the serial port, you cannot simply double-click an file in Windows 10. motorola gm300 programming software windows 10
Most users find success with an FTDI-based USB cable. Cheap "Pro-lific" cables often fail on Windows 10. This usually means the software can't see the RIB