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Blogs

Code and data structures starting to take shape

October 5, 2022 Retro Ports

Now that the “secrets” map is complete I’ve returned to RE’ing the code. The architecture of the code and data structures in memory are slowly starting to take shape. I won’t go into any detail at this point – mainly because it’s early days and I could have made some …

Blogs

Now with bonus Bonus Flags!

October 3, 2022 Retro Ports

Very quick update. A slight tweak to the sprite positions for the objects on the map, removed the Sol Tower in area 6 that doesn’t appear in the game to avoid confusion, and added the bonus flags. All secrets that appear in-game …

Blogs

Those pesky Sol Towers!

October 3, 2022 Retro Ports

 More eye candy, and another mystery! First something I mentioned in a few entries back; namely not understanding how two (2) banks of background tiles were selected. Turns out that bit 0 of the attribute byte (in bg_colorram) selects the tile bank. Easy explanation in the end. And although I …

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Blogs

The Xevious Map starts to reveal its secrets!

October 2, 2022 Retro Ports

A little more RE’ing and a lot more eye candy to come in the next few sessions! More work on decoding the area object tables; I can (syntax) parse the complete tables even though I have only identified (I think) the EVEZOO Easter Egg, ground-based objects and the bonus flags. …

Blogs

Characters, Tiles and Sprites

September 30, 2022 Retro Ports

Just a quick update. Yesterday I made some inroads into decoding the object tables for each area. I know the identifier bytes now for most of the static ground-based objects, including the Sol Citadels/Towers. What this means is that I can now, in theory, generate the definitive map with the …

Blogs

The Devious Map

September 27, 2022 Retro Ports

I’ve been plugging away at the RE since the last post, but haven’t been able to devote any large amount of time to it just yet, but thought I should post an update. I have made some progress on the SUB CPU which reportedly controls the graphics objects and hardware. …

Blogs

Xevious

September 23, 2022 Retro Ports

 After about 6 months of inactivity I’ve been motivated again to work on a retro project.A few days ago I saw a post about a YouTube video called “The History Of Xevious” Xevious gameplay After a discussion about the video on a shmup group I was also made aware of …

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Blogs

Do not under any circumstances try to use Ghidra.

February 28, 2022 Retro Ports

 What a f*cking waste of 3 days RE effort. I thought Ghidra was going well until tonight. Then I started losing random sections of work; code and data sections would arbitrarily revert to ‘unknown’, losing all comments and memory references with them. At first I thought it was my fault, …

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Blogs

Galaxian Part Nothing – The Holy Grail

February 24, 2022 Retro Ports

The last correspondence I got from Miro was probably not long after my last post in September. It seemed to me he was approaching this project from a different angle and I couldn’t really reconcile what I was doing with what he was doing. This is not a criticism in …

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Blogs

Galaxian Part 7 – Preliminary Impressions

September 7, 2021 Retro Ports

Whilst I’ve been waiting for Miro to digest the previous posts and hopefully develop his framework to the point I have described, I’ve actually been doing a little bit of the transcode. I’m not going to go into any specifics here as I’d like to document it in some form …