What is the writable memory module 6-37125 used for?

GVDobler posted:

Does one come with a 990 set? What are the blue ones used for?

The newer 990s come with 1 writable black module.  The Blue modules have the "shipped version" of Legacy software.

The catalog recommend one for base upgrades, cab-2 upgrades and system back-up. Do you need one for each thing?

While they recommend 2 modules for the upgrade 1 is all that is needed.  You write the base module, upgrade base.  Then use the same module and write the Cab module and upgrade it.  Having 2 is just more convenient. 

You can also use a black writable module to create a "multi-engine" module.  This is basically an Orange module on steroids saving the engine information of 99 orange modules including TMCC engines that you can choose to put on it.  It stores engine settings such as road name, road number, and settings such as type, control, and names same that the orange module comes with.  It does not store the engine ID.

Using the LSU (Legacy System Utility) software, which you will need to create the versions of the black modules above, you can back up your base database to a PC.  This includes base name, channel settings, and complete engine roster and engine IDs.  Switch, routes, accessory settings, etc.

How do they differ from a regular thumb drive? 

The connectivity is different.  I'm sure the computer folks could go into details.

thanks for any info.

FWIW, FYI, following the steps in this now 6y/o thread, you can convert blue modules to writable(black) in pretty short order.  Clear instruction and simple process.  With no prior knowledge of the workings in these blue modules I converted my blues in about 15 minutes each. Most difficult step was getting the plastic housing apart.   Now I have the two for upgrades, and one for backup of engine data.  free-black-modules-for-legacy

Thanks all new to me.