A “Scroll” is basically a successor to the modern day tablet PC. The name was just too obvious to pass up.
A Scroll basically consists of a fabric woven out of fiber optic strands with a hardened portion at top and bottom housing the bulk of the computer’s internals. The “fabric” is also reinforced to resist damage and has a layer of touch sensors underneath.
Hard light holograms are not available and a “Skinput” interface would not work through armor, or in adverse conditions such as a chaotic battlefield or a lack of sound medium (no air in space).
As established with the melee weapons, it’s possible that nerve impulse sensors could be used as an input method, but such a system would be more intimidating to new users.
Scroll is not such a great idea actually. It’s just an evolution of a tablet PC. Tablets are great in the sense that they let you rearrange the buttons on a device since they’re not really there, but don’t really have any more room for input than simple on/off buttons or click and drag.
Instead, maybe they have a device that looks like a camera, but where the screen should be, there’s a clip to hook it onto a vest or backpack strap. The lens projects a hologram, and the device tracks the user’s hands.
Maybe instead, it’s mounted on the inside of the wrist so that the hologram is projected right at the user’s fingertips. The device also has accelerometers to track it’s own movement and to keep the hologram steady. This way, the hologram can be twisted, pushed, prodded, and generally manipulated while still rooted to the user’s hand, in case they don’t have much room or need to keep a low profile.