First, what is a X-Terminator cartridge ? It is a Saturn flash cartridge which provides the following features :
- 1MB expansion RAM
- Backup memory
- Ability to play import games
- Cheat codes
- Ability to search cheat codes by using standalone "X-Assist" unit
X-Terminator cartridge and X-Assist
Image taken from SegaRetro
X-Assist is particularly convenient because unlike Action Replay cartridges, it doesn't requires connection to a PC : it is true that connection to a PC provides more features (such as memory access, program upload, etc), but as "connection to PC" basically means "software support will be dropped someday", a standalone unit is a real treasure
For example, do you remember that Action Replay cartridges initially had DB25 connector ? This was for connecting the cartridge to PC via the -sold separately- Comms Link board, whose used now obsolete ISA port, and consequently not supported on nowadays PCs and/or OS.
There are some alternate solutions for connecting Action Replay to PC, whose major one is USB Data Link, but unfortunately it doesn't provides any software support for advanced features such as cheat codes search and testing.
So if you want to search cheat codes for your favorite game, X-Terminator is a good choice ! ... Okay, the user interface is in Japanese, but that's just a detail : after 200 or 300 hours learning about it, it shouldn't cause any problems
On the other hands, the major limitations are probably the lack of 4MB expansion RAM support, and using flash ROM for storing backup save data (which on the long term may brick the cartridge), but for a cartridge developed more than 20 years ago, theses limitations are quite honorable
So, once upon a time, XRider found a X-Terminator cartridge. It was a cheap auction, but on the other hand the cartridge didn't boot anymore, and the X-Assist unit wasn't included
Normal people would add this cartridge to their collection or put it on display as a decorating vintage objet Other people with engineering and electronics education background would put it on their "to repair someday" cardboard, and don't touch it for the next 20 years because they are busy with other projects or work, or real life, or all of theses at once
But XRider is none of them. XRider owns soldering tools. And knows how to use them. And really wants to fix this marvelous cartridge
So, let's try to fix the cartridge ! The first step would be to start with the most common problem, which is broken flash ROM.
In my opinion, this is the most difficult step, because it requires to desolder two chips for a total of 64 pins !
I personally can't do this because of lack of appropriate tools, so the alternate desoldering way I would had used would be to ... use a nipper and cut each pins
Fortunately, XRider likes work well done, so theses chips were removed in a clean way
X-Terminator cartridge, with flash ROM chips removed.
Additionally, all capacitors are removed too : that's
the occasion or never to replace them
Dump is full of 0xFF bytes ... unless a miracle happens, theses flash ROM chips are no longer functioning But, this comforts us regarding initial supposition of broken flash ROM chips causing cartridge not booting
Just in case of, let's verify PCB traces around flash ROM chips while theses are removed : this takes only 5 minutes to check, and it would be frustrating to find that cartridge was not working because of broken trace after soldering new flash ROM chips
What to do next ? Maybe use PLCC sockets so that future replacement of flash ROM chips would be easier ! That's a couple of weeks to wait for the postman, but worth the wait
And then, simply replace the flash ROM chips
Next generation is here !
PCB with new flash ROM chips.
Additionally, new capacitors are populated
One last step remaining ! Flash ROM is mounted, but ROM itself needs to be set up with X-Terminator firmware. The simplest way to do this is to use Pseudo Saturn Kai flasher utility : it obviously allows to install Pseudo Saturn Kai, but also several other legacy firmwares in the case someone would want to revert to initial firmware after trying Pseudo Saturn Kai.
Flashing in progress ! Will it work after that ?!
Let's try with Metal Slug ...
Metal Slug works too !
So it seems there's no need to replace RAM chips
One X-Assist available ? And another one missing ? No problem : let's reverse engineer the first one and DIY the second one
The X-Assist features two PCBs : one for connection interfacing and pad, and another one for LCD, as pictured below.
The LCD board is incredibly complex, but since it was manufactured as a whole and can still be purchased on auctions or second-hand market nowadays, there's no real interest to build it from scratch ! And I personally wouldn't try : that seems too much complex
So remaining is pad and interfacing board : fortunately it uses standard components and not any Gate Array Logic-ish components that would need to be reverse-engineered too. Simply speaking, it's like assembling LEGOs
Multi-meter, a LCD board, electronic breadboard, a bunch of wires, few electronic components ... is there something missing ? Yes ! A LOT of motivation !!
Let's try for real ! Of course, after verifying any eventual short-circuit with a multi-meter
No short-circuit ? It's then ready for the "first-lighting ceremony" (火入れ式), as it is nicknamed in my neighboring ... I don't know if that's a common expression in Japan or anywhere else, but I like its naming anyway
At first glance, that seems working ! Let's try cheat codes search feature in order to be 100% sure ...
Arg, it was too early to sing victory X-Assist seems not being correctly detected by X-Terminator cartridge ...
Since text could be sent to the LCD, let's assume nearly everything is working correctly, and that a small detail is causing this trouble ... after some head-scratching, XRider found what's wrong : a Zener diode that initially looked useless was used to return some ACK to X-Terminator cartridge when looking for its connection !
code search memory could be captured !
65535 candidate codes ?! I'm not sure if correct cheat code could be found this time, but at least the DIY X-Assist unit works correctly now