Wiring a Socket
"She's made of hair and bone and little teeth / And things I cannot speak / She comes on like a crippled plaything / Spine is just a string" - "Tourniquet," Marilyn Manson
There are two main reasons for wiring a socket. Either the ROM you are trying to dump cannot be desoldered for some reason, or you are trying to dump something that your reader does not support. In the first scenario, you will solder wires directly between the ROM on the board and the pins on the socket, deciding which pins to connect simply by their physical locations (ie, pin 1 of the ROM goes to pin 1 of the socket, and you don't need to worry about what pin 1 actually is). Since that is MUCH simpler, I will start by explaining that first.
One good reason why you cannot desolder a ROM might be because that ROM does not physically exist. An example of that can be found in the P ROMs of the KOF2K2 bootleg. The ROM is actually a surface mount, but that is connected to where a normal DIP ROM would be located. I can dump that DIP ROM, but I cannot dump that surface mount. Unfortunately, there is no physical DIP ROM for me to desolder.
Here is a picture of the front:
What I need to do now is attach a wire between pin 1 of where the normal ROM would go and pin 1 of the socket. As long as I know what the normal ROM is and that my reader can support it, I don't really need to worry about what the pins actually stand for. In this case, I am basically wiring up the socket as an extension of sorts. It was more convenient for me to solder wires to the backside of the board in this case, so here is what it looks like flipped over.
Now personally, I like to prep the socket first. It IS possible to just wire wrap the wires to the legs of the socket, but I normally prefer to solder the wires into the holes connected to the legs of the socket. The reason for that is the wire wrap tends to come loose after a while, and I find it annoying to have to trace out which wires go where again. Look at this picture:
As you can see, the socket has holes above each of its legs. The holes are actually part of the leg itself. What I usually do is fill these holes with solder. Then, after stripping the end of the kynar wire, I heat up that leg again so the solder melts, and I stick the wire into that hole. After it cools, the wire is now stuck in that hole. Then I use a multimeter to test the connection between the leg and the other end of the wire to make sure that my connection is indeed good. You will notice that the first 3 holes of each column of legs have NOTHING in them. This is because this socket is a 48 pin socket, but the P ROM is only a 42 pin ROM. If a ROM does NOT take up all the pins of my reader, then my reader always wants the roms aligned so that there is space at the top. So that is why I have purposely left space at the top. As long as I leave those unconnected, my reader won't even see those as being present. Here is another picture of the socket (the circled pin is pin 1):
Now that I have my socket prepped and ready, it is time for me to attach the wires to the board. What I have to do now is very carefully make sure that I match up the pins so that pin 1 on the board goes with pin 1 of the socket and so on. It sounds VERY simple in concept, but it CAN get tricky sometimes, especially if you flip the board over, since then you will need to realize that you are looking at the entire thing from the underside (since you have flipped the board, right and left are also flipped). I find it helpful to orient your socket the SAME way that the ROM you are working with is oriented (ie, if you flip the board over, flip the socket over as well) when making sure that I have counted pins correctly. In this next picture, I have circled the two pin 1's. (Remember, I am not using thet top 3 wires of each column of pins on the socket.)
As usual, your multimeter will be your best friend in double checking when you're done with everything. Just flip it all back over so that you can see the front, then start testing and make sure all the pins match up correctly. Not only will you have tested that you counted all the pins right, you will also have confirmed that you soldered everything well.
Sometimes, doing a straight direct connection isn't quite enough to accomplish the task. There are times when you might not want all the wires connected directly. Usually, this is because you might need to manually bank a wire. Again, the KOF2K2 bootleg P ROMs provide a good example. When working with the P2 in bytemode (don't worry, I explain this in much more detail in the walkthrough section dealing with the P ROMs, for now, just concentrate on the wiring aspect), I had to manually bank pin 30. To do that, after connecting all the wires to the board, I cut pin 30 from the socket so that the wire was now only attached to the board.
I then stripped the now free end of it and wire wrapped it to where I needed it to go. In this picture, I have circled where I have wire wrapped it to GND.
Another reason to wire a socket is because your ROM reader doesn't support the ROM that you are trying to read. Usually, this means that the ROM you are trying to read won't physically fit into your reader. In these cases, I HIGHLY recommend you to either get a ROM reader that will handle the ROM, buy an adapter for it, or find another way to dump it. I do NOT recommend that you try to solder a socket to the ROM as an adapter yourself since the most common type of it-won't-fit is that you are working with a surface mount. These pins are EXTREMELY delicate, so if you were to try desoldering the whole surface mount and then attaching wires to the pins individually, chances are that you might mess up and destroy the chip. However, if there is some other scenario where it would somehow be ok to wire your own adapter (hmm... all I can think of right now is if you are working with a ROM that has maybe two more pins than you can plug into the reader and maybe you had to manually bank one of them or something simple like that), then here is how to go about it:
1. Get the data sheets for the ROM you are working with and the ROM that you plan to read the data into your reader as.
2. Look up what pin 1 of the socket will stand for. For this example, let's say that pin 1 (socket) = A18.
3. Find the pin on the ROM that stands for the same thing. For this example, let's say that A18 = pin 16 (ROM).
4. Attach a wire between pin 1 (socket) and pin 16 (ROM). Repeat until all the pins that you want connected are connected. Use a multimeter when you're done to check that all connections are good and that you didn't accidentally short anything you didn't want to.
5. Now connect any pins on the ROM that you need to manually bank.
6. Read. Change the bank settings to next setting that you need. Reread. Repeat until you have gotten all the data.
Here's what a socket hooked up to the ROM reader looks like:
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Walkthrough of Dumping the KOF2K2 Bootleg
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