When I was cleaning my NES carts the other day, I found that one of my two NES Zelda carts has an Eprom instead of the classic MaskRom it should have.

Can anyone tell me why ? Did Nintendo run out of the proper chips sometime in the 80s ? And why does an Eprom work without rewiring on a standard SNROM mapper board anyway ?

The version with the ceramic eprom is slightly heavier as well (122 instead of 116 Gramms for the cart with shell).

If I'm not mistaken the history of this particular cart is completely accountable. The cart was purchased in the 80s. Regular retail packaging. I'm in Germany by the way, so that's a european "golden" cartridge.

Here's a picture of the two boards. Left one is the standard Zelda PCB with a maskrom and on the right the version with a Eprom instead. Under the sticker there's a UV window.

From what I can tell there's no difference between the two and I'm really just wondering, why a mass-produced title like Zelda did get into stores with an Eprom ?

Any hints are highly appreciated ! Thanks, Fudoh

The one on the right seems to be an earlier revision of the board, as it's NES-SNROM-01 and the other is NES-SNROM-03.

is it possible it's a service center fix? there have been a few repaired carts shown around here with an eprom or two on a retail cart. maybe a factory refurb? it looks like its using the first version of the snrom board, so maybe they made some like that in the beginning. it's using a 27C301 eprom rather than the usual 27C010/27C101/etc used for eproms. the '301 is pin-compatible with the nintendo boards. there area few prototype photos on bootgod's site with '301 chips as well.

Yeah, what Lincoln said. Any chance I could see a nice picture of the back of the board? Just curious really.

Wow, cool find

[quote]Any chance I could see a nice picture of the back of the board[/quote]
sure! The service center theory above sounds solid. Still I'm wondering why they would put this kind of effort into repairing a cart. The cost for the Eprom alone is probably higher than for a full new cart, isn't it ?

It looks like two chips were manually added to the board. I wonder what 7Z meant.

Maybe its Zelda, Legend of ... you know.. flip it.

That's easy, it's the production code for the game. NES-7Z-USA. The ROMS also are labeled. Including even the EPROM.

ETA: The label also probably says ZL, 7Z is another game that's not zelda, while ZL is the first Zelda.

Makes sense to me.

I feel silly now, if you look closely you can read PAL-ZL-1 on the chip in the side by side photo.