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Stern SAM chksum
03-12-2012, 09:44 AM
Post: #1
Stern SAM chksum
Hi all, just registered.

Previously, I used Hexedit to change some of the text in the Iron Man, Tron, and Transformers flash images. This was to add some location specific phrases to the games.

However, with the latest release of the code for these games, Stern has added a chksum to the image. So now the game will no longer boot when the image file is altered in any way. Is there a way to bypass the chksum check or put in a new valid chksum?

Thanks,
Parker
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03-12-2012, 09:48 AM
Post: #2
RE: Stern SAM chksum
Are the latest games rolled into pinmame yet? If they aren't it would be difficult to do any (easy) real testing. It really depends on how intensive their checksum check is.

Try transposing some existing text to see if it fails the checksum then. If it does, they're doing more than a simple sum-up for the checksums.
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03-12-2012, 11:14 AM
Post: #3
RE: Stern SAM chksum
Thanks for the quick reply. As far as I know none of these games are in pinmame. I did try transposing some text and it it did not work.

Parker

(03-12-2012 09:48 AM)RalphButler Wrote:  Are the latest games rolled into pinmame yet? If they aren't it would be difficult to do any (easy) real testing. It really depends on how intensive their checksum check is.

Try transposing some existing text to see if it fails the checksum then. If it does, they're doing more than a simple sum-up for the checksums.
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03-13-2012, 10:01 AM (This post was last modified: 03-13-2012 10:02 AM by destruk.)
Post: #4
RE: Stern SAM chksum
We're hoping to be able to include all the SAM games by the end of the year (December 2012) as Stern will be pushing out a new hardware platform shortly thereafter. I'd vote for including them because the first game is now 6 or 7 years old (WPT) and I think we've all waited long enough. However, since even their last game will be allowed to run, other dev members might decide we need to wait another 3 years...

We are still searching for these game code revisions - the more code we have available the more insight we'll have into how the SAM system actually works.
24 1.20/1.10/1.00
Avatar 1.05/1.04/1.03/1.02/1.01/1.00
Avatar LE 1.10
Batman Dark Knight 2.30/1.40
Big Buck Hunter 1.30/1.20/1.10/1.00
CSI 1.01/1.00
Family Guy 9.00/6.00/5.00/1.01/1.00
Indiana Jones 2.00/1.15/1.12/1.11/1.10/1.09/1.08/1.07/1.06/1.05/1.04/1.03/1.02/1.01/1.00
Iron Man 1.50/1.30
Iron Man Classic (Requires Xylinx Serial connection to read code) 1.00
NBA 4.00/3.00/2.00/1.00
Pirates of the Caribbean 5.00/2.00/1.14/1.12/1.10as/1.07/1.06/1.05/1.04/1.03
Rolling Stones 1.04/1.02/1.01/1.00
Simpsons Kooky Carnival 1.04/1.02/1.01
Shrek 1.40
Spiderman 1.50/1.10
Transformers 1.30/1.10/1.00
Transformers LE 1.21/1.10
Tron 1.00
Wheel of Fortune 4.00 SPANISH
World Poker Tour 1.07


That said, there should be a way to bypass your checksum issue, and/or generate a new checksum to allow it to work - just I don't know where to begin. The start of the game code is the bootup diagnostics, followed by the game code and logic, followed by a huge chunk of audio data, and ending with a little more code. I'd guess the checksum is stored at the end like WPC. Worst case is you could use an earlier revision of the game you are modifying before the checksum was added.
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03-13-2012, 10:59 AM
Post: #5
RE: Stern SAM chksum
I did check to see if I have any of those old version of code and don't. I had some of them at some point in time but must have cleaned off the older ones from my local storage.

Would be nice to see SAM games in pinmame at some point.

There is an additional feature that SAM games have that I don't think existed before. That is the on board flash ram, Spansion S29GL256N11, which is 256 MegaBIT. The game code is stored there, of course. But other information is also stored on the flash ram. When you load a new version of the code the display says "erasing flash" as the first step but it does not erase ALL of the flash. Not sure if this will be something NEW that pinmame will need to consider?

Stern does not provide a utility to completely clear the flash ram and taking the battery out does not clear it, of course. One bit of info stored here is the "lifetime" audits. When selling an operated game I called Stern and asked for a way to clear these audits as the the earnings are not anyone else's business. Interestingly, the "total plays" is not stored as a lifetime setting. Only "paid plays" and "total earnings" are lifetime stats - so the game could have 10,000 free plays on it and you could reset it completely. But the paid plays could not be. Stern told me the "lifetime audits can not be cleared."

Rumor has it that Stern did this at the request of a large European distributor who was concerned that there was some stealing going on by people making collections and resetting audits. But we DO want to clear this audit and I spent a bit of time finding a way to do so.

Parker



(03-13-2012 10:01 AM)destruk Wrote:  We're hoping to be able to include all the SAM games by the end of the year (December 2012) as Stern will be pushing out a new hardware platform shortly thereafter. I'd vote for including them because the first game is now 6 or 7 years old (WPT) and I think we've all waited long enough. However, since even their last game will be allowed to run, other dev members might decide we need to wait another 3 years...

We are still searching for these game code revisions - the more code we have available the more insight we'll have into how the SAM system actually works.
24 1.20/1.10/1.00
Avatar 1.05/1.04/1.03/1.02/1.01/1.00
Avatar LE 1.10
Batman Dark Knight 2.30/1.40
Big Buck Hunter 1.30/1.20/1.10/1.00
CSI 1.01/1.00
Family Guy 9.00/6.00/5.00/1.01/1.00
Indiana Jones 2.00/1.15/1.12/1.11/1.10/1.09/1.08/1.07/1.06/1.05/1.04/1.03/1.02/1.01/1.00
Iron Man 1.50/1.30
Iron Man Classic (Requires Xylinx Serial connection to read code) 1.00
NBA 4.00/3.00/2.00/1.00
Pirates of the Caribbean 5.00/2.00/1.14/1.12/1.10as/1.07/1.06/1.05/1.04/1.03
Rolling Stones 1.04/1.02/1.01/1.00
Simpsons Kooky Carnival 1.04/1.02/1.01
Shrek 1.40
Spiderman 1.50/1.10
Transformers 1.30/1.10/1.00
Transformers LE 1.21/1.10
Tron 1.00
Wheel of Fortune 4.00 SPANISH
World Poker Tour 1.07


That said, there should be a way to bypass your checksum issue, and/or generate a new checksum to allow it to work - just I don't know where to begin. The start of the game code is the bootup diagnostics, followed by the game code and logic, followed by a huge chunk of audio data, and ending with a little more code. I'd guess the checksum is stored at the end like WPC. Worst case is you could use an earlier revision of the game you are modifying before the checksum was added.
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03-13-2012, 12:56 PM (This post was last modified: 03-13-2012 12:56 PM by destruk.)
Post: #6
RE: Stern SAM chksum
The extra Spansion ram is only present (and therefore only used) on ACDC's hardware. It will also be used on their last two SAM games they make later this year. So I don't think it will be a very big issue.

There might be other audits and adjustments being saved in the basic 32 or 64mb of ram all the other SAM machines come with - I haven't checked into those too closely.
If you feel up to it, you could desolder the flash ram chips, and replace them with new ones - then power the machine up and see if those audits are cleared or not.
The machine should still boot up off the U6 chip and allow you to install the game code again.
If it doesn't work, you can resolder the original chips back onto the board.

(low-tech testing is usually safest)
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03-13-2012, 01:24 PM
Post: #7
RE: Stern SAM chksum
Good to hear the spansions won't be an issue for possible future pinmame use.

The chips are surface mount and have a lot of tiny tiny legs so I won't be desoldering those! But that is OK as I no longer need to find a way to erase them Wink

Parker

(03-13-2012 12:56 PM)destruk Wrote:  The extra Spansion ram is only present (and therefore only used) on ACDC's hardware. It will also be used on their last two SAM games they make later this year. So I don't think it will be a very big issue.

There might be other audits and adjustments being saved in the basic 32 or 64mb of ram all the other SAM machines come with - I haven't checked into those too closely.
If you feel up to it, you could desolder the flash ram chips, and replace them with new ones - then power the machine up and see if those audits are cleared or not.
The machine should still boot up off the U6 chip and allow you to install the game code again.
If it doesn't work, you can resolder the original chips back onto the board.

(low-tech testing is usually safest)
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03-13-2012, 01:38 PM (This post was last modified: 03-13-2012 01:39 PM by destruk.)
Post: #8
RE: Stern SAM chksum
As far as code goes - Stern has a tendency to release code without adding it to the revision history - so I'm not sure if there every really was an Avatar LE 1.10. There is 1.01LE and 1.00LE. The readme for the rev history goes from 1.20 to 1.01 and then 1.00.
Other times they add release history entries for game code that the public never saw, and that was never available for download on their website, or code that was uploaded for 10 minutes and immediately replaced with a new version on the same day. I wish they'd be more forthcoming about their updates, like sending an email to owners when one becomes available rather than requiring owners to click each link every day to check, or that they would keep and document their old code - but I have no say in the matter. Smile

About storing settings and audits - I would find it much more likely that they are all saved in the same nvram/flashram area as all the other saved settings - and that a factory reset or clear command just doesn't remove them from that space, rather than saving them somewhere unique on other chips or expansion chips that aren't on all models of the hardware.
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