A vertical autoloader design enables multiple data cartridges to be selectively loaded into a drive while minimizing the device footprint. The structure of the vertical autoloader incorporates Geneva steps into the walls of the autoloader. The Geneva steps interface with gearing on a drive carriage to move the drive vertically. The data cartridges are inserted into slots on the front of the vertical autoloader, and the data cartridges not currently loaded into the drive can be removed and replaced while the autoloader is in operation. Further, the vertical autoloader includes prevent devices in the cartridge slots to ensure the data cartridges are loaded correctly.