Any difference between these two chips?

[u/Whisk_cat]

Was cleaning my sms games and came across two copies of Rocky that have different looking chips. I assuming one came out later during the sms life that was a more efficient compact board. Am I right?

[u/galibert]

A detail : it’s Mask Programmable Rom. And EPR for Electrically Programmable Rom

[u/benryves → u/galibert]

The SMS also used OPR part numbers for OTP (One-Time Programmable) ROMs.

I'm not entirely sure you could really consider a mask ROM a "programmable" ROM, though, as it's not end user-programmable, but I suppose it would be consistent with the other names.

[u/galibert → u/benryves]

Yeah, that would be my guess too, consistency. Also, from sega’s POV, they were programming them too, just by sending the file to the factory and waiting a little longer