> It's super annoying that USB-to-Parallel adapters cut corners and only transmit the bare minimum signals to print to an inkjet printer. That's because they w

> It's super annoying that USB-to-Parallel adapters cut corners and only transmit the bare minimum signals to print to an inkjet printer. That's because they weren't USB-to-Parallel adapters, they were USB printer adapters. A parallel port was effectively a GPIO port to which most people happened to attach a printer. There is no standard USB device class for arbitrary GPIO devices. The USB printer class is defined to make sense for native USB printers, so USB printer adapters present the same to the host and then convert this to a parallel format. This is a lot more efficient than having a device that actually implements arbitrary GPIO and then bitbanging those lines to speak to the printer. You might similarly note that a USB gameport adapter won't work with some higher end devices that "hacked" the port to offer force feedback and/or more than the expected amount of buttons, because the USB HID game controller class is designed to efficiently handle native devices rather than to support all possible weird ways one could use a port in the days of raw hardware access.