This shot illustrates the huge amount of human factors research and work to get from A to Z:
Screen size evaluations, different aspect ratios, resolutions, available components, nice-to-have vs must-have components and, most importantly, modularity!
This beast has been designed with multiple housing options:
- different keyboard configurations/layouts
- different scan and imager engines
- different antennas etc
- multiple battery options (and hence different covers)