Data storage devices

Data Storage Devices are a set of quest items from Deus Ex: Human Revolution's DLC, The Missing Link. They are rewritable (though not by Adam Jensen) and designed to hold various types of information, such as holographic, biometric, and miscellaneous data.

Background
Jensen may come across a total of four in-game, with the first (yellow) being unavoidable; it will be given to Jensen at the end of M1 - Getting out of the frying pan, and later used by him in order to progress through the main mission M2 - In the Belly of the Beast. The other data storage devices may easily be acquired while completing this mission, though do not relate to it specifically.

The three other DSDs (blue, red, and green) are scattered about the Rifleman Bank Station and their collection is entirely optional. These three are each paired with three holographic tables found in the the Seafloor Laboratories belonging to doctors Tiffany Kavanagh and Gary Savage. Despite having nothing to do with the main quest-line, each will grant 100xp when placed on their respective tables, as well as create an intriguing and unique hologram. Doing so for all three will also grant the achievement The Learn'd Scholar.

Furthermore, each device is labeled 'OCM' along with their particular holographic title. OCM stands for 'Organic Computational Matrix' and is the topic of research and development at the Rifleman Bank Station laboratories. Thus, it seems clear that the locations depicted on the holographic projections are slated for massive computer systems dependent upon OCM-augmented individuals.

Location of Optional DSDs
The blue and red DSDs are found above the Seafloor lab, and the player must collect them before descending to the Seafloor lab, as the lab can only be visited once. Once in the Seafloor lab, the green DSD and the hologram tables can be found. The below maps show where the three are located, where the arrows are pointing:

Panchaea
The blue holographic storage device is located in the Operations Security office, in the lower level of the Admin Sector, just past the Loading Bays.

It depicts the first five Panchaea installations - two in the Atlantic, two in the Pacific, and one in the Indian Ocean. It is unclear what is meant by the size of each holographic installation, though #5, the one Adam visits near the end of Human Revolution, is the largest.

Australia
The red holographic storage device is located in the Archives office, to the right of of the double doors leading to the Morgue (on the same level where you meet Nina Sullivan).

It depicts an installation in central Australia, presumably an HQ during the civil war. The exact location seems to be Ayers Rock, given the title and general area.

Moon Base Omega
The green holographic storage device is past the Morgue, down the restricted elevator, within the Seafloor Laboratories -- the same place where the holographic tables are located.

It depicts a sizable base on some unknown stretch of lunar terrain. This is the first known evidence depicting the colonization of the moon in the timeline of the Deus Ex franchise.