I have the graphics to exile somewhere and they're a 10K 4 colour block extremely tightly packed ready for recolouring, rotation etc. It might not be possible to create new graphics without spoiling the game but I wonder if anybody has ever tried reverse engineering Exile like the author of Elite-A did with Elite.

The reward? Finally the sequel Exile always deserved and not some PC conversion but on an Acorn.

My mate Matt started work on a fully interactive intelligent disassembler app a while back, with the exact intention of reverse-engineering Exile and generating some meaningful source code, which could then be amended, if desired, and recompiled (in BeebAsm!).

It was at quite an advanced stage (I remember we pretty much nailed Chuckie Egg, with meaningful label names for code and data) but I think he never added all the features we needed for Exile, and in any case, we never started the long job of interpreting the Exile code.

Maybe something will come of it one day.

And your mate will be being introduced to these forums ... when exactly?

Heh... well he doesn't have much time these days unfortunately... he's over on STH but rarely pops in any more.

Will find out what state the app's in these days - maybe what there is can be released.

Bingo! If we can start getting this sort of stuff "parked" online, someone else might express an interest. Maybe you should point him at the new flashy theme over there, that might blind him into sticking around more (or he'll have tried Vista and therefore seeing the STH theme will send him into a blind rage).

Sam.

Just to clarify - it would still require a fair deal of user intervention to create perfect source code. For example, it couldn't possibly automatically spot things like:



but as the user inspected the code by hand, it would certainly offer 'routine MOD 256' and 'routine DIV 256' as options for those two lines.

It was quite a fun little app to use though - very rewarding to identify the purpose of a small subroutine, give it a sensible label name, and then magically start to see the higher-level purpose of other subroutines become clear as the JSRs inside them.

Here's a little screenshot of Chuckie Egg being reverse-engineered.

oh dear... how can I not stretch the forum with that picture?

Back to the hex editor for fixing my monster bugette... (sigh)

Hmm ... we have two options. One is for you to edit the post and reduce the width to approx 670px and then I can put in a limit which stops ppl uploading up such wide attachments in the future.

The other is that I add a mod which resizes the image in a browser (effectively adding a width=670px tag, if the image is too wide). Generally, I'm against installing mods unless they're absolutely necessary, but in this case I can see there's a benefit to uploading larger images.

I'll take a look at it when I get chance at home ...

Sam.

Well, at least it only stretched my post, and not every post on the page!

I've seen other messageboards which place embedded images inside a horizontally scrollable frame, so that the forum width is preserved, and the image remains at its correct size. Don't know if you know of anything like this at all...?

you lost the source code?

(I love the meandering directions this thread is taking )

There're a few related phpBB mods, but the ones I've seen appear a bit ... errr ... amateurish. I'll have a proper look at home. I'll write my own, if necessary. Personally, I'd prefer to have the pic resized to fit in the post and the option to open it up in a new window, if I need to see it bigger, though I guess I can look at scroll bars if I'm in the minority.

Sam.

Hehe that chuckie asm is ace, top darts!

No definitive final set of source code... but with what I do have all is not lost because I'm sure - even with only 30 bytes free - I can patch out the last bug.

What was the function of the self-modifying code again? I thought it was for the loader and protection?

OK, put in a neat stylesheet fix.

Large (> 660 KB) pictures should now fit into the forum properly, and can be seen at full size by viewing the image separately - right-click and select View Image in Firefox.

Sam.

Self-modifying code isn't for anything particular - it's an efficient and valid programming technique under certain circumstances. Happens to be useful for protection because at first glance everything is nonsense.

I like the way you phrased your question. "What was..." not sure if that was meant to be humorous, but it appealed to the funny-sensor in my brain!

I remember getting "bored" of the protection on exile and removing it. It wasn't that hard. I probably can find the disc if it is of interest?

I should really make another release of my emu sometime. It has a full built in assembler/disassembler and also makes a very nice job of commenting code automatically for you...

The disk protection, or the password protection on Exile? It would be good to compare methods.
I posted my disk protection bypass here
http://www.stairwaytohell.com/sthforums ... 926&p=4494

Having an emulator with a good disassembler would be good too!

That has been something of a fantasy of mine for many years...

If I knew the first thing about 6502 assembler I'd have turned my hand to trying to reverse engineer it myself... but I wouldn't even know where to start!