USB-A/B for USB2.0 lacked the pin-count to provide compatibility with other connector standards by using a passive adaptor (except a few like PS/2). It also lac

USB-A/B for USB2.0 lacked the pin-count to provide compatibility with other connector standards by using a passive adaptor (except a few like PS/2). It also lacked the data bandwidth to encapsulate many other connector electrical protocols when using an active adapter except a few like RS-232 and 100mbps Ethernet. It also couldn’t deliver much power either - 500mA at 12V is only 2.5W - enough for a mouse or webcam.