Firstly I would like to say that I am not trying to compete with Benny's modchip. I'm planning on buying a few when they are available. After my recent TSOP flashing failures, I started to do some research into an easier way to recover than the old 29 wire eeprom method as that requires an eeprom programmer. What I have found is a dual interface flash EEPROM with both an LPC interface and a standard parallel interface. The idea is the chip plugs into the LPC connector, boots Cromwell and then flashes itself with a stock or hacked BIOS from a DVD. The chip is then removed from the LPC interface and soldered in the same as the cheapmod. From then, the process is the same as recovering TSOP using a 29 wire mod. The advantage of this is is that you can use the xbox itself to flash your BIOS of choice via LPC, and not need a parallel programmer. After the TSOP is repaired, you can remove the chip, re-connect it to the LPC bus and reflash Cromwell and keep it ready for the next emergency. You could always leave the BIOS on it and then it is ready to be used as either an LPC mod or a 29 wire mod. As said before, I came up with this idea as a way to repair a bad TSOP without needing an EEPROM programmer, and apart from having some solder pads for a bunch of wires, it is nothing more than an LPC boot device and an adaptor board for the Xbox LPC. The EEPROM is a Microchip SST49LF008A in a 32PLCC package. You could just solder wires directly to the device and use it deadbug style. Boot with a "normal" modchip and hotswap to flash a BIOS onto this. No CPLD/FPGA, just one device and a PCB, or one device and a shit load of wires. Hope this idea is of some help to anyone in the same situation as I am
You are slightly confused here. The EEPROM is an 8-pin SOIC package, it contains your hard drive key among other information, and can be read/written using 3 wires. The TSOP, which is really just a 32pin flash chip in a TSOP package (see what they did there?), contains the BIOS. The 32 pin PLCC package you speak of is for a model of a compatible flash chip that has an LPC interface since that was the easiest and cheapest way to throw it into a socket back in the day. I also see a couple design flaws in your design. Firstly, what happens if you flash the modchip with an image you can't boot? If you flashed the onboard TSOP with a bad/incompatible image what is stopping you from doing the same to your modchip and not being able to write cromwell, or any other image, to it? This is why the real modchips use a CPLD, it gives you a way to recover using backup firmware or some external programming means. Secondly, the whole reason that chip was chosen back in the days of the cheap mod was because it has an LPC interface, so you can just solder if to the LPC interface and not have to do the 29 wire mod, so the process is not the same as doing a 29 wire mod. Flashing it twice sounds like a pain and gives you two chances to screw it up every time you use it with no way to recover from a bad flash. This is why chips like the xecuter 3 used a 2Mb flash chip and gave you the ability to use banking, so you could have multiple flash images to boot from on the same chip. Lastly, it is not easy to find the the LPC flash chip you are speaking of, it was discontinued a long time ago. I don't know that you can even find a compatible flash chip with an LPC interface as part of the package, no one is using those anymore. If it was easy to find there would probably be someone on this forum selling them preprogrammed in the marketplace. All in all I would say you are better off finding an X3CE and one of those dinky solderless adapters, or just buy pin headers from digikey, and playing around with that until you learn which BIOS images do what, how the size of it affects how it will boot, etc. You can't just flash any image to an unmodified console, it has to be the right size, have the right EEPROM options, is the board 1.6 or not, etc, otherwise you will get the results you have already gotten. I don't really know what your procedure was for doing the TSOP flashing on your consoles, but it sounds like you just threw the wrong BIOS image at a couple of consoles. You can't just flash any old image, it has to be compatible. Evox M8 is pretty good and IIRC it will work on an unmodified console. Flashing BIOS is like throwing an engine in a car, sure you can throw ANY engine in if you are willing to do the engineering and fabrication it will take, or you can just buy the same engine from a different model car and it will probably be plug-n-play (for a lack of better words...). Best of luck to you in recovering those consoles.
Flash is a marketing name for block-erase EEPROM . They are exactly the same apart from "normal" EEPROMs can be erased and written at a byte level, flash requires a whole block or sector to be erased or written at once. The IC itself is still made and readily available, I'm buying a few next week. I shared this info more for people who already have an LPC modded console, and can use the LPC header to program this modchip if needed. There's many reasons a flash can fail, this gives an easy way to get data onto the device, and an interface that's compatible with the onboard flash in the event of a flash failure. It is a bit of a long winded way of recovering from a bad flash, but it saves on requiring a parallel programmer or trying to get hold of a "normal" modchip. It's only recently that I've found out how the D0 grounding actually forces the console to boot from LPC. Apart from forums like this, information is getting hard to find. I've tested BIOS's on my modchips, then flashed to TSOP if the console boots and runs properly, now I know that some images have bit 0 set to 0, causing a good flash to boot from LPC, thinking the flash is empty. Computers, electronics, engineering and mechanics are my background. I've never really looked deeper into modifying the Xbox than finding the D0 point on the board and soldering it to my Duox-2 until recently. It never occurred to me that D0 is actually a data line until recently. I'm better at designing my own hardware than working out others if someone else has already done it.
