HP48GX USB Cable Using the XMODEM Protocol for File Transfer (HP48 to USB Cable). By Teknovo1 in CircuitsComputers3,8026Save PDFFavoriteIntroduction: HP48GX USB Cable Using the XMODEM Protocol for File Transfer (HP48 to USB Cable).By Teknovo1FollowMore by the author: Setting up the USB Cable for the HP48 Graphing Calculator Series: HP48GX, HP48G+, HP48G, HP48SX and HP48S.