: On "Expanded Logic Board" models (typically 16-channel versions), you can program the accessory jack pins (6, 8, 9, 12, 14) for binary-coded channel selection. This allows you to select channels externally, which is vital for building repeaters. Channel Expansion

This is the most convenient method as it allows you to stay within your Windows 10 environment. Download and install DOSBox on your PC. Mount the Software: Create a folder for your Go to product viewer dialog for this item.

This write-up covers the necessary software, hardware requirements, and the specific steps required to successfully program a GM300 on a Windows 10 PC.

Your GM300 is not obsolete. You just need to give it a modern brain transplant via a virtual serial port. Once programmed, that radio will outlive your Windows 10 computer.