Interest in pin matched adapters for SOIC 39SF040 ROMS for Translations

[Arkanix38]

Hi all!

I have been wanting to play my Final Fantasy Carts for a while, and got around to testing the pinouts for the 256 and 512k ROMs. I'm not a fan of altering existing boards any further than switching the ROM. As SST still manufactures the 39SF040 in SOIC form (still around $2 a chip i think) I thought it would be a good idea to test the pinouts and make up a compact adapter board in Eagle. The two boards directly remap the 39SF040 to either the 256k or 512k standard mask ROM pinouts and hence do NOT require trace cutting or pin bending when placing a translated ROM in a game. I've kept the dimensions so that when soldered in, the board should not interfere with the case. It should be theoretically possible to switch ROMs back without damaging the board or requiring manual rewiring of the traces.

The only difference between the 256 and 512k boards is the addition of a connection to A18 from pin 2 of the mask ROM port.

I have the design up on OSH Park, would anyone be interested in using the adapter board for translating their games?

Ark

[80sFREAK]

Hi all!

I have been wanting to play my Final Fantasy Carts for a while, and got around to testing the pinouts for the 256K('020) and 512K('040) ROMs. I'm not a fan of altering existing boards any further than switching the ROM. As SST still manufactures the 39SF040 in SOIC form (still around $2 a chip i think) I thought it would be a good idea to test the pinouts and make up a compact adapter board in Eagle. The two boards directly remap the 39SF040 to either the 256K('020) or 512K('040) standard mask ROM pinouts and hence do NOT require trace cutting or pin bending when placing a translated ROM in a game. I've kept the dimensions so that when soldered in, the board should not interfere with the case. It should be theoretically possible to switch ROMs back without damaging the board or requiring manual rewiring of the traces.

The only difference between the 256K('020) and 512K('040) boards is the addition of a connection to A18 from pin 2 of the mask ROM port.
...

fixed.
This is good idea, i thought about it back in the days, when worked on MMC1 based flashcart. To make it as cheap as possible, you have to panelize and use one of those "prototype services". Is your design for single side or double side pcb?

[Arkanix38]

Double sided, could't find a way to route the +5V without using a single (the only) via on the board. On reflection the 256k('020) and 512k('040) can BOTH use the same adapter board, with pin 2 pulled from the adapter to prevent use of the upper bank of memory in the 39SF040 (or with the ROM doubled up to fill space).

I HIGHLY sugest using the 39SF040 as all of my local suppliers have it for roughly half the price of the 39SF020 ($2 vs $3.95 AUD).

[80sFREAK]

You can use "jumper" (zero ohm resistor) to bring your design to single side. If so, you can make single side pcb at home very easy.

[Arkanix38]

Great idea! No idea why I didn't think of that...
Stuck an 0805 SMT jumper in there and presto, one sided!

Edit: My huge container of Sodium Persulphate has been rather neglected recently. Good chance to use it up!

[jensma]

Nice idea!

Can you pop the adapter into an programmer to write your rom to it?

[80sFREAK]

I think you have to programm first and solder after or either to make custom adaptor for programmer

[Arkanix38]

Nope, Write Enable pin is permanently pulled high and Output Enable is permanently pulled low. Kind of like a one time Write thing for translations. Don't really want to make an adapter for flash carts and the like.

[jensma]

That's bad luck, I don't own an soic adapter for my programmer

Btw, aren't there already plenty tsop to dip adapters which would do the job? Or did I miss something?

[80sFREAK]

Mask ROMs have different pinout, isn't it?

[jensma]

Mask ROMs have different pinout, isn't it?

Yep, they do.

I'm talking about these adapters:

https://oshpark.com/shared_projects/Xn0qMKIY
https://oshpark.com/shared_projects/KT0o1xzP
https://oshpark.com/shared_projects/JC0MXRHj

[muckyfingers]

I'm interested. 

[Arkanix38]

There are probably other projects out there that do the same. My aim was to have an adapter that would allow me to just swap the roms and not worry about the messy business of cutting traces. I also wanted to have an adapter for cheap in-production ROMs.

My next aim is to figure out a way to use 32mbit flash roms in my SNES, although im having a little confusion figuring out how to program the chips with my TL866 in BYTE mode rather than word mode

[jensma]

Ah, alright! I'm interested in one adapter, if you could flash it for me I got a Dragon Quest VI somewhere lying around which deserves a translation.

[HVC-Man]

There are probably other projects out there that do the same. My aim was to have an adapter that would allow me to just swap the roms and not worry about the messy business of cutting traces. I also wanted to have an adapter for cheap in-production ROMs.

My next aim is to figure out a way to use 32mbit flash roms in my SNES, although im having a little confusion figuring out how to program the chips with my TL866 in BYTE mode rather than word mode

Just so you know, there do exist TSOP to DIP adapters for SNES.

http://www.buyicnow.com/it.php?i=983

(the item in question is TSOP Adapter III)