Four, typically, along with three things that could be called pointing devices. (That would be a laptop's built-in keyboard, a proper external keyboard, the hot

Four, typically, along with three things that could be called pointing devices. (That would be a laptop's built-in keyboard, a proper external keyboard, the hotkeys on a Wacom tablet, and a programmable keypad to make Ctrl+Alt+Shift+[optional Fn if using a compact/laptop keyboard]+[whatever]+"hold your tongue in precisely this position while trying to do things with the other hand using a pressure-sensitive pen" key combinations into a single simple keystroke, the laptop's pointing device, an external mouse, and the actual tablet part of the Wacom.) And yes, there are home and travelling versions of the set-up. People seriously working in 3D, non-linear editing, and so forth, would have more. Things can get rather complicated in a hurry when the computer becomes the core of a dedicated toolset that can also be used, on occasion, to perform simple administrative tasks like email, invoicing, ...