How can I tell if my ECU has an EPROM?

One fact that is not mentioned on this page is how to quickly check ECUs *after 1990* for an EPROM. There is a label on the top of the ECU (not the sides). If this label has an "E" in the lower right-hand corner, you have an EPROM. If it has an "M" or "T" in that corner, you do not have an EPROM. 1990 owners have to open the ECU to find out, as there are both EPROM and non-EPROM 1990 ECUs. This tip is also on this page from the developers of the DSMlink.

Galant VR-4 owners, again, have an edge - owing to the low production volume of that model, GVR4s are almost guaranteed to have an EPROM.

Great thread on DSM tuners: http://www.dsmtuners.com/threads/how-to-identify-an-eprom-ecu.337343/