Lately I bought a Zastone D9000 2m & 70cm radio without a programming cable (as always when I buy radios 😁). From online pictures of the original programming cable I reverse engineered the pinout and built my own one from a FTDI USB to TTL-Serial converter that every ham should have. In addition, I found out that the MIC connector pinout in the radios manual is wrong (mirrored).
Info: It is important that your USB to serial converter outputs 5V levels not 3V3 or other voltages, otherwise this won't work.
Extra Tip: You don't need a special cable for connecting the display to the radio. A standard LAN cable also works.
The original diagram shows the front view of the socket but this is wrong. It's the front view of the plug.
Cut open a standard LAN cable and connect it to the USB to serial converter according to the picture above. Orienting by the colours should work (Connect: green to FTDI Gnd, blue / white to FTDI RXD, orange to FTDI TXD).
Display must be connected to main unit while the radio is powered on. I didn't try programming on any other ports so far.