The very earliest Legacy CAB-2's (hand controllers) were incapable of being updated in the field. As a result those of us who had them had to ship them back to Lionel for upgrade to Version 1.2 before we could do our own upgrades.
Once they are at v1.2 they can be updated in the field to v1.3 by using a black writable memory module.
All later versions (after v1.3) including to 1.6 and 1.61 are upgradable without using the black writable module, simply by connecting the CAB-2 base to a PC, with an appropriate cable, and using a management utility (Legacy System Utility, Version 2.0, 6-37125) on the PC to do the upgrade.
You can find some details, and the CAB-2 software, here: https://www.lionelsupport.com/LegacyBaseReturn/
If you haven't already done so it would help to register your CAB-2 set with Lionel because the black writable memory module with v1.3 will be sent to you free of charge if you do.
Good luck. It's not too hard.
Mike
