nesdev.org

Hey there community,

I searched the web but couldn't find an answer to my problem. Maybe you guys can help me. I did some SNES-Repros in the past but I'm new to the NES

I'm about to build an Earthbound Zero for my collection. Is it possible to burn it on two 27C256's? The PRG and the CHR-File are 256kb in size.

If it is burnable, how to connect the eprom to the PCB?

I got this information from this site:

TKROM & TSROM (mapper 4):
PRG socket:
Bend up pins 1, 2, 24, 30 and 31 (or cut tracks 2, 24, 30 and 31)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
Solder pin 31 to hole 2 (A18)
CHR socket:
Bend up pins 1, 2, 22, 24, 30, 31 (or cut tracks 2, 22, 24 and 30)
Solder pin 2 to hole 24 (A16)
Solder pin 22 to hole 31 (CE or CHR /A13)
Solder pin 24 to hole 2 (OE or CHR /RD)
Solder pin 30 to hole 1 (A17)

Well, a 27C256 has just 28 pins, so erm.. I don't have to mind the information about what to do with pins 30 and 31, right?

Any help is highly appreciated

The number at the end of the part is kilobits, so a 27C256 → 32KiB. For 256KiB you'd need a 27c2001 or something equivalent.

lidnariq wrote:The number at the end of the part is kilobits, so a 27C256 → 32KiB. For 256KiB you'd need a 27c2001 or something equivalent.

Damnit, I felt for the '256' :/ Thanks for the info

27C256 is a 32KB chip. And the ROMS you slit aren't kb, they are KB. Bytes. You'd need 8x 256's for each program and characrer side. You need a 27C020 for *EACH* side. And there should be wiring sheet on the front page. You should be able to work on from there.

ETA: Tokumaru has a point.

3gengames wrote:27C256 is a 32KB chip. And the ROMS you slit aren't kb, they are KB. Bytes. You'd need 8x 256's for each program and characrer side. You need a 27C020 for both sides. And there should be wiring sheet on the front page. You should be able to work on from there.

Got it, thanks a lot!

You guys are great

You can use FLASH (29F) instead of EPROM (27C). It is cheaper.

3gengames wrote:You need a 27C020 for both sides.

You can't put both PRG and CHR in the same chip though, it has to be 2 chips.

tokumaru wrote:

3gengames wrote:You need a 27C020 for both sides.

You can't put both PRG and CHR in the same chip though, it has to be 2 chips.

Yep, I know

socram8888 wrote:You can use FLASH (29F) instead of EPROM (27C). It is cheaper.

Mhh, yeah, you're right. I never thought about that, I always used eproms for repros. And my willem seems to be able to burn the 29F* without any additional adapter.. that's cool And they're indeed way cheaper than the eproms. Thanks for this great hint!

socram8888 wrote:You can use FLASH (29F) instead of EPROM (27C). It is cheaper.

what are the part #'s for 29 series 2 mbit chips? and where do you buy them that they are cheaper than eproms?

29F020, and anywhere that has chips?

Use 29F040 or 28F020. They are both on eBay for less than 4USD each with shipping.

If you're looking for a source other than eBay for whatever reason I would recommend Futurlec. They have decent prices, very reasonable shipping (that's a recent change, used to be not so good) and decent customer service. They also have a lot of supplies and protoboards and such at great prices.

socram8888 wrote:Use 29F040 or 28F020. They are both on eBay for less than 4USD each with shipping.

Thanks for the hint - I built Erthbound Zero today with two 27c020. Next time I'll use Flash ROMs

qbradq wrote:If you're looking for a source other than eBay for whatever reason I would recommend Futurlec. They have decent prices, very reasonable shipping (that's a recent change, used to be not so good) and decent customer service. They also have a lot of supplies and protoboards and such at great prices.

Thanks for the link - I'll bookmark it & ask how much shipping to germany would be

Oh, Germany There's a lot of good suppliers in the EU. Others on this board would better know which ones carry vintage parts. I've never looked into them much due to the shipping.