To connect your radio to a PC, you will need a with a "Kenwood-style" 2-pin connector.
These are generally more reliable as they auto-install drivers on most modern Windows systems. RT Systems and various eBay sellers offer these for the PX-777. puxing px-777 programming software download
When you purchase a "PX-777 programming cable" (typically a Prolific PL2303 or FTDI chipset cable), a mini-CD is included. While old, this CD is often the most reliable source for the exact software version matched to your radio's firmware. To connect your radio to a PC, you
: A standard K-plug (Kenwood style 2-pin) USB programming cable. : Ensure the a mini-CD is included. While old