I've got the jacksum working, but the problem I have is if I take the navboot file, remove the the last 3 bytes, then pass it through the jacksum app. I get a different checksum to what is in the file.

So the question is: what part of the navboot file do you chop from the file before passing it through jacksum?

I hope you understand....cos I only just do!

can someone post a clone cd or iso image of the 26.09a update with the plain jane mkiv ===bmw=== logo? you'd be my hero. i know just enough hex to screw up my nav drive, i'm sure.

thanks

Okay boys I'm one step closer I haven't tried it yet. Seems as though somethings have transpired overnight and I had to do some research. Anywho, thanks to "ambishop" for pointing me to jacksum. I have indeed verifed the checksum on my hacked version of "navboot" and the original V26 file. They are indeed identical. Now the testing begins.

Off to my car. I'll report back as soon as I can. Pray for me folks

Since it seems I was the one that originally started this craze, it's only fair that I answer.

Here are a few notes, speaking from personal trials (yes, I was brave enough to try on my OWN nav computer)

1) No, you cannot "permanently" screw up your nav computer with a corrupt image. If you screw up the checksum with an invalid GIF89a image, the disc will either NOT boot, or will boot and hang during the middle of the install

2) Dont panic, turn the car off. If you have a video module, when you turn the car back on, you'll have a very rudimentary main menu. Eject the disc from the nav computer, and insert a FRESH copy of v26. Give it a few MINUTES (not seconds). It will eventually boot and load the fresh copy of v26 back onto the computer. Then you're free to go back into the house and continue hacking the OS LOL

DISCLAIMER: Just because I've flashed mine about a ZILLION times and not killed it, doesn't mean you'll do the same LOL

Now, for the other news.

I have NOT changed the logo, but I have been able to successfully REMOVE it from the code.

There is indeed a checksum, however, we need a Microware OS-9000 guru to figure out that portion.

I have a copy of IDA PRO if anyone needs it (with the OS-9000 plugin)

I think this is a smarter approach. Using V26 software we should just enable the features we are looking for

Martin

I like this stuff. Reverse engineering at its best.

We're praying beedeeman!!!! You reverse engineers rock! This is better than watching 24!

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Some systems use multiple checksums, one on each block of code/data, and then another at the end of the data.