Retrode Community Forum

General Category => General Discussion => Topic started by: ICEknight on 25/Feb/2012 03:17:55 PM

Title: Individual chip dumping through the Retrode?
Post by: ICEknight on 25/Feb/2012 03:17:55 PM
I was wondering if it would ever be possible to have an option in the config file that allows for getting the data for each individual chip that's holding the game's data in the cartridge, instead of having all of the game's data combined.

This would require the Retrode to (somehow) autodetect the chip size, and would only be useful for preservation purposes and not just for general emulation, so I'm not sure if it would be too much of a hassle since it's not the primary aim of the device.
Title: Re: Individual chip dumping through the Retrode?
Post by: Matthias_H on 25/Feb/2012 04:40:02 PM
Problem is, in most cases with two separate ROM chips they are wired to behave EXACTLY THE SAME electrically as a single chip twice the size. Do you have a specific example; a game that doesn't work or something?
Title: Re: Individual chip dumping through the Retrode?
Post by: ICEknight on 25/Feb/2012 09:01:24 PM
Well... I do have a Mega Drive game that shows all of its odd bytes (or even bytes, can't remember) as having garbage, while the rest are seemingly correct, but I don't really know what's up with it.

What I thought is that, having the data split between the different "true" ROMs might help tracking any busted chips that other cartridges could have, and would also be of help when burning a new chip with the specific data that's needed in those cases (you'd just need to plug a working cartridge and get the needed data only).


In any case, sooner or later, somebody might want to start documenting each of the chip's data separately for preservation purposes, so it would be just an overall handy feature to have as an option. :)
Title: Re: Individual chip dumping through the Retrode?
Post by: Matthias_H on 26/Feb/2012 06:58:34 AM
What's the title? It would be rather helpful to have some PCB shot or even a schematic, since I can't imagine why one byte should be working and the other shouldn't.
Title: Re: Individual chip dumping through the Retrode?
Post by: ICEknight on 26/Feb/2012 08:33:37 PM
It's Home Alone, PAL version.

I'm sorry I currently can't open the shell to see what's inside, as I don't have the required screwdriver for it. =\
Title: Re: Individual chip dumping through the Retrode?
Post by: Matthias_H on 27/Feb/2012 03:22:34 AM
I'm sorry I currently can't open the shell to see what's inside, as I don't have the required screwdriver for it. =\

Best trick ever: Heat/melt a piece of plastic (ball pen, etc.) using a lighter, press quickly and firmly into screw head. Wait five seconds, voilĂ  - your new custom screwdriver! Simply turn to remove screw, and re-use it on the other side and for re-assembly.
Title: Re: Individual chip dumping through the Retrode?
Post by: ICEknight on 27/Feb/2012 04:04:11 AM
Best trick ever: Heat/melt a piece of plastic (ball pen, etc.) using a lighter, press quickly and firmly into screw head. Wait five seconds, voilĂ  - your new custom screwdriver! Simply turn to remove screw, and re-use it on the other side and for re-assembly.
...Just did that and now the screw has a solid piece of plastic around it. Now I can't open it up without breaking the case. =\
Title: Re: Individual chip dumping through the Retrode?
Post by: Matthias_H on 27/Feb/2012 04:23:22 AM
Maybe not the best trick then. It worked zillions of times for me. (sigh) Sorry if this caused any trouble for you.
Title: Re: Individual chip dumping through the Retrode?
Post by: ICEknight on 12/Mar/2012 10:10:35 PM
Now this is odd. I've tried dumping my working copy of Turrican, and a similar error is happening no matter how much I clean the contacts. Are there any known compatibility issues with this one?

The strangest thing is that it shows a 64kb TRIA.bin and a 1024kb TRIA.srm, the former showing interleaved '00' bytes and the latter just showing half of the bytes:

TRIA.bin
Code: [Select]
.S.G. .E.E.I. .
.(.).C.D.1.9...U
. . . . . . . .
. . . . . . . .
. . . . . . . .
.T.R.I.A. . . .
. . . . . . . .
. . . . . . . .
.G. .C.D.0. .0..
.J. . . . . . .

TRIA.srm
Code: [Select]
SG EEI 
()CD19.U
       
       
       
TRIA   
       
       
G CD0 0.
J       

I didn't have any problems with any of my other non-pirate games (except for the busted Home Alone), though.

EDIT: When passing it through an adapter, I get a "XtxrxixaxXXXXXXXXXXXXX.bin" and a "XtxrxixaxXXXXXXXXXXXXX.srm", the second one with the same contents as before and the .bin replacing the interleaved '00's with '78's ("x").

EDIT 2: Funny thing is, that "fake" .srm might be precisely what I was asking for in this topic, a dump of just one of the internal ROMs.
Title: Re: Individual chip dumping through the Retrode?
Post by: Matthias_H on 13/Mar/2012 04:35:47 AM
Not too strange, actually, to see the ROM mirrored in the SRAM file. After all, the ROM is on the data bus by default, so if there is no SRAM we will see a chunk of ROM. Although I do find it rather unusual to have "X"s instead of zeros or 0xFF. Anyway, we need to find a way to unlock that upper byte, and I guess it can't be all too hard. Have you managed to open the cart to see what's inside?
Title: Re: Individual chip dumping through the Retrode?
Post by: ICEknight on 13/Mar/2012 10:34:55 AM
I've being able to open the Turrican cartridge (since the screws are different), and the game seems to be contained in just one ROM.
(http://img829.imageshack.us/img829/7333/turricaninsidefront.jpg)
(http://img714.imageshack.us/img714/168/turricaninsideback.jpg)

The other two chips... I don't know what they might be.
Title: Re: Individual chip dumping through the Retrode?
Post by: Muzer on 13/Mar/2012 12:34:55 PM
The other two are just hex inverters, I believe (with my limited electronics knowledge).
Title: Re: Individual chip dumping through the Retrode?
Post by: Matthias_H on 13/Mar/2012 04:01:23 PM
7404 is a hex inverter, 74374 an octal D-latch. That should be fairly easy to get running, but I'm afraid the photos are not quite enough. Do you have a continuity tester (multimeter with beeping function)?
Title: Re: Individual chip dumping through the Retrode?
Post by: ICEknight on 13/Mar/2012 08:18:06 PM
I'm afraid I've never come across one of those in my life, sorry...
Title: Re: Individual chip dumping through the Retrode?
Post by: Matthias_H on 13/Mar/2012 10:12:19 PM
Okay then, maybe I'll just meditate over the pictures for a bit longer and see if I can come up with something. That latch is a bit unusual to find there. Don't have a lot of time at the moment but in a few weeks perhaps...

Edit: Actually, I might as well just get a copy of Turrican / Home Alone. What are the exact titles you are referring to?

Cheers,
Matthias
Title: Re: Individual chip dumping through the Retrode?
Post by: ICEknight on 14/Mar/2012 10:22:04 AM
Edit: Actually, I might as well just get a copy of Turrican / Home Alone. What are the exact titles you are referring to?

These are the offenders:

(http://img221.imageshack.us/img221/844/offenderseqxv.jpg)
Please do note that I never got that Home Alone cartridge to work in a Mega Drive, so there's probably nothing odd inside working copies.

Also, the Turrican cartridge says "for use in Genesis systems", but it was released in Europe like that.