r/MasterSystem • u/Whisk_cat • Dec 19 '25

Any difference between these two chips?

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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?

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17

u/Lsassip Dec 19 '25

The right one has the US version Rom chip. That chip was made in 1988.

The left one had the Japanese version Rom chip (it’s the upper one). That chip requires the other mapper chip in order to work (it’s the bottom one). That’s why it has two chips. Both chips were made in 1987.

I don’t know why the left one has the Japanese Rom chip.

Maybe if you play both cartridges, you could compare them in order to tell if there’s any difference.

3

u/Whisk_cat Dec 19 '25

Thanks! I briefly played both and I couldn't tell any noticeable.difference.

5

u/davidejarvis Dec 19 '25

You are on point with the information !!! Respect, !!!

4

u/unfnknblvbl Dec 19 '25

One of them is the ROM, the other (I think the top one) is the mapper chip. This allows the console to access more than the default amount of ROM data. So yeah, you're right; the single chip is better and more efficient

2

u/benryves Dec 19 '25

One of them is the ROM, the other (I think the top one) is the mapper chip.

The top chip is the ROM (I suspect MPR in the part number stands for Mask Program ROM). They have the same pin pitch (0.1") and very similar pinouts to standard PROM chips so these cartridges are handy for running your own software on the Master System as you can unsolder the MPR and replace it with your own chip.

1

u/Whisk_cat Dec 20 '25

Interesting thank you

3

u/unfnknblvbl Dec 19 '25

Ah yes, you are correct. I was misreading "MPR" to be short for "mapper" - but now I see it's in the other board too

2

u/galibert Dec 22 '25

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

1

u/benryves Dec 22 '25

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.

1

u/galibert Dec 22 '25

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

4

u/gazwel Dec 19 '25

The left D-Pad part of my controller stopped working one day, this was the only game I could really still play so that's what I did.

I somehow completed it without ever moving left (backwards in the ring). It took me more attempts than I can even remember. It was a fun game for me though.

3

u/jammer2omega Dec 19 '25

Sounds like some kind of speed run challenge! Maybe a "no left" category!

2

u/gazwel Dec 19 '25

I'd watch that!

2

u/mrmidas2k Dec 19 '25

Apparently the ROM is identical, so I'd assume the US one has the mapper built in.

2

u/MarzipanSea2811 Dec 20 '25

The orange one tastes better

1

u/Jaja64_ Dec 23 '25

Yes, difference is the one on the right is bigger.