Power Macintosh G3 (Blue and White): ADB and USB Devices Simultaneously Supported
It is possible to use both USB and ADB input devices on the Power Macintosh G3 (Blue and White).
Be aware that if you have two similar input devices, such as a USB mouse and an ADB mouse connected simultaneously, the results are unpredictable and it is not recommended. However, using a USB mouse with an ADB keyboard, or vice versa, is fine.