Got interested in the recent Spider WIP improvements and the correlated Table Tennis Championship development, I’ve decided to take a look at this exotic FPGA-based video blitter.
The thing is definitely weird, as Haze also explained in his blog it basically reads an i/o port to enter into “blitter mode”, and any following write to the memory mapped bus actually routes to the blitter, and using the address bus instead of the data bus either for obfuscation or performance reasons.
It’s not a novelty (Sharp X1 Japanese computer line did something similar back in 1981) but definitely a bit annoying, and the main roadblock towards emulation of this game until today:

Over the past week, me and Olivier Galibert ironed out several issues in the Seibu COP simulation. This includes Zero Team not crashing anymore and this one happening …

… and yes, this one means that both Raiden 2 and Raiden DX are now (almost?) working. I have doubts especially towards DX just because I haven’t yet checked out if beating properly Alpha Stage doesn’t have issues (and yes, it’s amusing having this kind of doubt now, compared to just one week ago).

Starting to work on Sega Model 2 HW, which definitely deserved some love for the importance that this HW went in mid-90s. With some aid from from Haze, providing snippets of information from ElSemi’s code here goes some WIP snaps:

Fighting Vipers

Last Bronx

Sega Rally (added “Eye Mode”, used by car selection)

Virtua Cop

Virtua Cop 2 (no textures, if it wasn’t clear)

Virtua Striker

Of course it’s still a long way to go. And anyway, main problem lies in FIFO comms: BOTH CPUs stalls at arbitrary points in several games (Virtua Fighter 2, Fighting Vipers and so on), trying to read an empty FIFO instead of alternating between reads and writes.

Got basic understanding about how the 3d pipeline works in Hyper Neo Geo 64. Basically it was an irq issue (one unimplemented irq is needed at FIFO processed) plus some other things like swap / clear buffer that were hooked up in the previous update.

Fatal Fury Wild Ambition

Beast Busters 2nd Nightmare

Off Beat Racer / Xtreme Rally

Roads Edge
Note: definitely behaves oddly on gameplay (most 3d missing plus unplayable)

Buriki One

Finally, both Samurai Shodown are currently with broken 3d, that’s because they sets up the 3d upload register differently compared to the other games.

Did some work with Hyper Neo Geo 64, tried to understand some stuff (namely z80 network cpu and 3d pipeline) and read a bit of MIPS code for Buriki One. Got a cheap work-around for the coin insertion so got it to go into gameplay:

EDIT: Played with debugger, entered into service mode and hooked up inputs in Roads Edge. Camera seems very jumpy, I wonder if we have a CPU core bug here …