You plugged it in, Windows installed "something," but your software (like Mach3, WinLPT, or a DOS app) still says "LPT port not found." Frustrating, right? I've been there. Let's fix it.
The "good story" for most users isn't the code itself, but the struggle to make it work in a modern environment: CH351DS1.PDF - Nanjing Qinheng Microelectronics Co., Ltd. ch351q parallel port driver
Your old software wants 0x378 . The CH351Q is at 0xDFA8 . You have two choices: You plugged it in, Windows installed "something," but