Before answering that question, a little history lesson will help understand the issue and the suggested solution.
The ProSoft 3250-L532M SLC 5/03 RTU processor's operating system (OS) firmware is 100% compatible only with Allen-Bradley's (A-B) M11 and M12 EEPROMs. However, these EEPROMs are no longer available from A-B. If you can locate one of these via the second-hand market, you can install and use them with no problems reading or writing.
The 3250-L532M is also capable of reading a program from a M13 EEPROM once the program has been stored on it; but is not able to write a program to the M13 EEPROM. The inability to write to the M13 EEPROM is a result of the older operating system revision used on the 3250-L532M not having the necessary algorithm to write to those newer EEPROMs.
The M11 and M12 EEPROMs were based on 12 volt technology memory chips. When those memory chips became obsolete and no longer available to A-B, they developed the M13 EEPROM, which uses 5 volt technology memory chips. The 5 volt chips can be read by any OS version but require a different algorithm for writing to them than was used for the 12 volt chips in the M11 and M12 EEPROMs. Therefore, the 5 volt algorithm had to be added to the operating system (OS) firmware. A-B did this with the release of their Series C OS.
The Series C OS is a newer OS release than the one used in the ProSoft 3250-L532M solution. Therefore, pre-Series C OS processors, like the ProSoft 5/03 RTU, can read programs from a M13 EEPROM once the program has been stored on it; but can't write a program to the M13 EEPROMs. Nor can the OS in the 5/03 RTU be upgraded to Series C.
However, one possible work-around exists. If you have any SLC processor with OS Series C or higher available to you, you can download your RTU 5/03 program to that SLC and use it as a "surrogate" processor to program the M13. Then that M13 EEPROM could be installed in a RTU 5/03, because any SLC can read what's been stored on the M13.