MAMEWIP
Ville Linde posted the following regarding his development for MAME:
December 25, 2006
Merry Christmas!
I wasn’t planning on making updates on Christmas, but this one seemed major enough ;-)
One of the most interesting parts of the Taito 3D hardware is the math co-processor that has been integrated into one of the Taito custom chips. The coprocessor does two functions. The first function does 3D point projection to 2D, and was quite straightforward to understand from the DSP disassembly. The second function however, required a lot more head scratching. Eventually I figured out that this function is used to calculate polygon intersection calculations while clipping the polygons against the viewport.
The reason why yet another math unit is needed may not be clear at first. But once you look at how the math functions work, it becomes more clear. Both of the math functions are dividing something, and a quick look at the TMS320C51 datasheet reveals that it doesn’t have a division unit at all.
The emulation of the math co-processor, coupled with some additional TMS320C51 bug fixes gives us almost perfectly working 3D.
