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Pseudo Saturn Kai no longer working on Action Replay ... and its rebirth !

Written by cafealpha 2 comments
So TehNewParalyzer told me he likes Pseudo Saturn Kai and plans to put many Pseudo Saturn Kai videos on his youtube page.
Very good ! That's great to see people still enjoying using Saturn nowadays

Metal Slug with Action Replay cartridge,
compatible until you press Start button
(Click in order to see youtube video)

At that time, his last video was about Uno DX, and was experiencing issues with it.
That's a bit weird, because this game shouldn't cause compatibility/problems ... maybe a bad burn or bad dump of the game ?

By looking at the problem in details (everything is explained in his videos, which is very convenient  ), I see that CWX loader doesn't works anymore for all his games, even the ones that played well before, but JHL loader still works well.
Very weird : CWX hasn't the best game compatibility, but should work on all known models of Saturns

So I request TehNewParalyzer to give details about this problem :
1. From loader selection menu, press B button, select "Self Test", and select "Test once only".
Please let me know if error message is displayed in "Main prgm" or "Bootstub" lines.
2. Please try CWX loader with an original game, and tell me if it booted or not.
3. If possible, please try with game burned on another CD-R brand and/or burned a different (lower or higher) speed than usually, and tell me if it boots with CWX loader or not.
4. If possible, please try with another Saturn and tell me if you can get games booting.
5. If you have a spare Pseudo Saturn cartridge (Action Replay, or Game Shark, or Memory Cart Plus, or any other clone), please give a try with it and tell me if you can get games booting.

Fortunately, there wasn't need to test after step 1 : self test feature was throwing a CRC error on when checking firmware's main program.
Okay, so it looks like cartridge flash ROM is corrupted, and consequently few areas in main program code can't longer be executed.
Why Action Replay's flash ROM would corrupt ? I don't know exactly, but I suspect :
1. Extra feature in Uno DX, corrupting cartridge's firmware in the case you use too much +4 cards
2. Poor quality of Action Replay flash chips.

Rather than thinking too long about causes, let's take measures in order to fix the problem : re-flashing the cartridge should do the job.
And it did the job : no more CRC error

Correct self-test results after firmware re-flash.
(Click in order to see youtube video)

One of the purposes of Pseudo Saturn Kai's self test feature is to help Action Replay users : by the past, I had few reports from other users having their Action Replay no longer working, so I thought about a feature in order to check the integrity of their flash ROM.
I'm glad this feature was useful to at least one Pseudo Saturn Kai user


For those who want more details about Action Replay flash chips :
First, Action Replay cartridges (and their clones) are using old flash chips no longer produced, which means theses chips are either old, or counterfeit. In both cases that means the quality of this chips is a bit shady.
Moreover, Action Replay original firmware may shorten flash ROM life length, because it writes to flash ROM when cheat codes selection is changed, or when cartridge internal save functionality is used : the more you store save data, or select Action Replay codes, the more likely it is to be damaged.

There are ways to improve this problem : the simplest one is to use SST39SF flash chips (5V logic, still produced ), but that requires changes on Action Replay PCB, and to make several changes Action Replay firmware (because write access to new flash chips is not compatible with old ones).

Changes in PCB is probably not a real problem for Action Replay manufacturers, since Action Replay PCB is shrinking year by year (in order to reduce manufacturing costs) so I suppose that Action Replay manufacturer still have at least one guy capable of designing PCB ...

Changes in Action Replay firmware is probably what's preventing manufacturers from using new flash chips : people who wrote Action Replay original firmware (around 20 years ago !) are probably retired now, and I doubt there are still people fluent with SH2 assembly working in Action Replay manufacturing field

A little unrelated (but I'm too lazy to create an article just for that) : Pseudo Saturn Kai compatibility list is growing little by little
There are currently 259 games available in the compatibility list, so there are high chances to find your favorite game listed in it

Special thanks to people who contributed to this list, especially Thales Peres, who provided test reports for around 150 games !


#1  - cornflake said :

Hey man, I was just reading through some of you stuff, very interesting. I had an idea, what if we were able to create a something similar to a breakpoint on certain key press such a start or key combo like r+start in the modified AR firmware/loader that could substitute for in-game pause? may help the gfx corruption issue. I maybe out of my wheelhouse here, I've got an AR cart coming in today so I'll have to better feel for what's going on then and see if I can contribute and do some testing in my spare time. Thanks for all of your hard work.

#2  - cafealpha said :

@cornflake : Thank you for your interest :) I didn't started anything regarding support of games requiring RAM. The breakpoint idea is good, but a bit tricky to implement. On custom cartridge side, it would be interesting to "see" (with LED turning on, etc) if games access at RAM mirror areas or not : this is very probably what's causing glitches on Metal Slug.


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