If you are trying to use an SDR1000 with a modern OS PC, a Greek ham came up with a modern interface, Pi SDR-IQ. Christos used an Orange Pi and a daughter board to interface the audio(I/Q) and a LPT port adapter to tie in controls of the Flex to Orange Pi. This then plugs into the USB port of any PC. Works pretty slick
https://pi-sdr.net/pi-sdr/index.php/pi-sdr-projects/pi-sdr-iq-plus