Older generations of some Line 6 products are is not updateable with a download and requires the installation of an E-Prom to update the firmware. Unfortunately, Line 6 no longer offers EPROM upgrades. Technology life cycle has made it not viable to buy the blank EPROMs through normal commercial channels any longer.
Here is a list of such products:
AxSys
AX2
Flextone I/II
POD/POD Pro 1.x
BassPOD/Bass POD Pro 1.x
HD147