Source

So I’ve been spending a good amount of time reverse engineering the Zeus chip’s behavior. Thanks goes out to the folks who offered to loan me a Mortal Kombat 4 board. So far I haven’t had to hack into it yet, but as I delve into some of the more esoteric behaviors of the chip, I suspect I will need to eventually. The board I’ve been loaned has at least been very helpful to understand what things are supposed to look like.

 

In the past few days I’ve finally figured a number of things out….

 

First off, textures now appear to be correct in most cases. It turns out there are a bunch of subtleties in the texture handling, including per-quad offsets, independent U and V coordinate scaling, ignoring the low address bit, determining when to make things transparent, etc. Getting these basics figured out means that the games are now respectable looking.

 

I knew Invasion ran on the same hardware as Mortal Kombat 4, but the way it handles models, textures, and interrupts was quite different. I think I’ve finally reconciled most of it, so the game boots, coins up, and plays, though there are still a bunch of models missing and glitches to figure out. I also need to hook up the light guns so you can actually try playing.

 

Even better, Mortal Kombat 4 is mostly playable, at slow speeds (no serious optimizations yet). Lots of glitches remain, but it fundamentally works, which is pretty thrilling given where I was a couple months ago.

 

As I’ve been figuring stuff out, I’ve been adding to the rapidly expanding Midway Zeus wiki page. This is pretty much a brain dump of how I understand the chip to work, and writing it down has helped me deduce a bunch of stuff.

 

Yet there are still a bunch more things to figure out, such as alpha blending effects, lighting, missing bits of models, extra vectors and matrices I don’t understand, crashes, weird results, etc.

Commodore Plus/4 emulator

v1.39 (XII-2007)

 

* added possibility to set video mode in the *last-change*command line options;

* fixed some bugs

>> Get it HERE.

TG16 / PCE emulator

A new version of MagicEngine for Mac is available :

 

MagicEngine 1.0 PR 10.3/ OS X (universal binary)

 

* fixed the font path problem in OS X 10.5

* fixed a configuration problem when multiple different gamepads were connected

* added a new fullscreen resolution (same as desktop)

* fixed a bug in the video settings panel

* fixed a memory bug that could crash the program

* added a French translation of the OS X menu

>> Purchase it HERE.

PS2 emulator

This is a bugfix to yesterday's release.

Noteable changes in this beta:

 

FFX Fixed, was a serious timing bug on IOP i made, suprised more didn't break.

>> Get it HERE.