Here is my collection of firmware dumps for this series. The DL4 and MM4 are from pedals I've owned or repaired, the FM4 image I found online.
Stickers on the EEPROMs and text data in the images refer to version numbers but I've never actually seen any different revisions.
DL4 1.3:
https://drive.google.com/file/d/0ByVCt2OFhXnyVF9kZnRXTDJTNEk/view?usp=sharing&resourcekey=0-86887qF7KuqQq77nf4Vd7A
MM4 1.0:
https://drive.google.com/file/d/0ByVCt2OFhXnyNURXckFJUTlJYmc/view?usp=sharing&resourcekey=0-DM-HZXCfQB50_p-1awD_cg
FM4 1.0:
https://drive.google.com/file/d/0ByVCt2OFhXnyZUx2R0RSQTBzc00/view?usp=sharing&resourcekey=0-1ak_q2Ip8ABL4MlzcFJE2g
I am still hoping to do a mod to switch between different firmware images. I was hoping that I could find larger pin-compatible EEPROM and toggle some address pins but the larger chips seem to have different pin-outs. Making an adapter board to go in place of the socket is probably the way to go but I haven't really had the time.
Once again, if there are copies of the firmware from the AM-4 and DM-4 please get in touch.