3 ms·

Now that’s an old-new-thing post I’d like to read! I assume because serial mouse support ca. 1996 is baked deeply into the USB standard, so you can’t pass conn

Now that’s an old-new-thing post I’d like to read! I assume because serial mouse support ca. 1996 is baked deeply into the USB standard, so you can’t pass connect-a-thon/compliance tests without it?

wongarsu 2y ago
It might also just be a situation of "it's there, doesn't hurt anyone, doesn't cause much work, removing it could hurt someone". Windows needs (or at least used to need) keyboard support earlier in the boot sequence than mouse support. It's plausible that they load the entire USB stack early on to get keyboards etc working, then sometime later some ancient code iterates all serial ports to check for serial mice. To that driver, USB-Serial bridges and "native" serial ports should look the same through the hardware abstraction layer. The leaked Windows XP code contains a lot of ancient code, some apparently taken from MSDOS. They later removed some of that, but apparently not this part.
- kotaKat 2y ago
  > It's plausible that they load the entire USB stack early on to get keyboards etc working, then sometime later some ancient code iterates all serial ports to check for serial mice. To that driver, USB-Serial bridges and "native" serial ports should look the same through the hardware abstraction layer. That's exactly it. When a serial port is initialized on Windows, it looks for data coming in, and if the right 'garbage' at the right time is picked up, Windows will then hook the mouse driver. https://roborooter.com/post/serial-mice/ https://roborooter.com/post/serial-mice/ discusses the fairly simple protocol at hand. This can lead into the unintentional effect of "plug in <serial-based device, like a GPS>, mouse suddenly goes wild". In my case... works as designed - serial mouse on USB-C dongle just works ;) https://www.taltech.com/support/windows_2000_nt_serial_mice_and_missing_com_port/ https://www.taltech.com/support/windows_2000_nt_serial_mice_...
dmitrygr 2y ago
It isn't. Serial mouse protocols are nothing like USB HID protocol.

wongarsu 2y ago

It might also just be a situation of "it's there, doesn't hurt anyone, doesn't cause much work, removing it could hurt someone". Windows needs (or at least used to need) keyboard support earlier in the boot sequence than mouse support. It's plausible that they load the entire USB stack early on to get keyboards etc working, then sometime later some ancient code iterates all serial ports to check for serial mice. To that driver, USB-Serial bridges and "native" serial ports should look the same through the hardware abstraction layer. The leaked Windows XP code contains a lot of ancient code, some apparently taken from MSDOS. They later removed some of that, but apparently not this part.

kotaKat 2y ago
> It's plausible that they load the entire USB stack early on to get keyboards etc working, then sometime later some ancient code iterates all serial ports to check for serial mice. To that driver, USB-Serial bridges and "native" serial ports should look the same through the hardware abstraction layer. That's exactly it. When a serial port is initialized on Windows, it looks for data coming in, and if the right 'garbage' at the right time is picked up, Windows will then hook the mouse driver. https://roborooter.com/post/serial-mice/ https://roborooter.com/post/serial-mice/ discusses the fairly simple protocol at hand. This can lead into the unintentional effect of "plug in <serial-based device, like a GPS>, mouse suddenly goes wild". In my case... works as designed - serial mouse on USB-C dongle just works ;) https://www.taltech.com/support/windows_2000_nt_serial_mice_and_missing_com_port/ https://www.taltech.com/support/windows_2000_nt_serial_mice_...

dmitrygr 2y ago

It isn't. Serial mouse protocols are nothing like USB HID protocol.