Next and finally in the technical posts on the architecture of Batrider Chase!: the PS3 version. The PS3 runs the same C++ game core as the Vita version: the decompiled game rebuilt from the Ghidra project, with Chase! Mode, the menus and the extra features on top. The Cell processor is a very different machine from the Vita. It has one general-purpose PowerPC core (the PPU) with two hardware threads, plus six SPUs available to games. Each SPU is a fast vector processor with its own 256 KB of local memory. The RSX is the GPU. The first build ran everything on the PPU and was far too slow on a real console, so the work was spread out: the PPU runs the game, and the SPUs do the drawing. Below is the PS3 version diagram. Sound: Like the Vita, the PS3 runs the original sound board with nothing pre-rendered: the Z80 sound program, the YM2151, and both 6295s playing the original ADPCM samples from the sound ROMs. With the whole board on the game's thread, the game ran in slow motion, so the board is split across the PPU's two hardware threads. The game thread runs the Z80 and the chips' timing right alongside the main program, since the two talk to each other constantly, and writes down every chip write with the exact sample it happened on. A second YM2151 and pair of 6295s on the synth thread replay those writes and generate the waveforms. The output is bit-identical to running the whole board in one place. The synth thread has the highest priority on the system. It feeds 48 kHz stereo to the PS3's audio out and keeps 100–150 ms queued, so the sound holds steady through the busiest scenes. Graphics: The tile data is the original ROM, untouched, and stays in main memory. Every frame, the PPU splits the 320x240 picture into five bands of 48 rows and hands one to each of five SPUs. Each SPU pulls in the frame's sprite and tilemap state, then fetches the 8x8 tiles it needs into a 1,024-tile cache in its local memory. It draws its band in the arcade's own priority order: the backdrop, the three tilemap layers and the sprites across 16 priority levels, then the text layer. Flips and mirrors are handled as each tile row is drawn. Each SPU then sends back its band turned upright, plus a priority map the hitbox uses. It also sends its share of the final picture at 3x size, with scanlines added when they're on. The SPUs' picture is pixel-identical to the reference renderer, and 60 frames of every play session are checked against it. On a real console, drawing the picture used to take about 7.5 ms of every frame on the PPU. The SPUs now do it in parallel. The sixth SPU scales the Chase! gadget panels, which are composed in spare PPU time a few times a second. The PPU lays the Chase! overlay and the hitbox on top. The RSX doesn't run a single shader. Its transfer engine scales the finished picture to the TV at 720p or 1080p, places the gadget columns down each side, and flips on vsync. TATE mode turns the whole screen for a TV on its side, with the gadget panels moved to strips at the top and bottom. So the PPU's threads run the main program, the sound, the screen and the gadget panels, and the SPUs and RSX handle all of the drawing. The game never waits on the picture: if a frame isn't drawn in time it's skipped, and the game and sound keep running at the arcade's 59.6 Hz. #CoinOpGameStudio #Batrider #Raizing #PS3

Following yesterday's short demo, today I am showing you the PSVita version of Chase. I like this better because the CPU behaves to my liking and achieves slowdowns properly in heavy areas, and it's my favorite version to play. I received some messages yesterday in terms of ideas towards a legal pathway to make this available. Obviously it's a free game, but I would have to share it in such a way to not breach copyrights. So still currently researching a legal pathway to make this available.

This is a short demo of something I worked on for the past few months on and off and more during the summer when I was travelling without access to my computer: youtube.com/watch?v=QDetNkc6… It's a remaster/ remix of Batrider called Batrider Chase! It does not use emulation at all, it started out as a decompilation effort and then transitioned into a reimplementation effort. I replaced the sound and graphics drivers too, and made the music stereo instead of the mono on the original board. There is also an option for custom soundtracks and redbook audio I intended to get to, but didn't. The backend is C++ and it is multiplatform. It works on N64 and Saturn (some frame drops due to the limits of the system) and it also works on PC, Vita and PS3 (Full game with gadgets). I did this project primarily for learning purposes to learn about decompilation projects. Having gone through the exercise, I did not see a legal pathway to releasing this, so it remained and still remains internal and amongst friends.