Hit & Run PS2, recompiled for PSP

A new engine for the PSP

Written in C with PSPSDK. It reads the game’s own data from your disc and drives the PSP’s chips directly. Nothing of the PS2 is emulated

About 28 fps on a PSP-2000, all 7 levels

One chip does almost everything

The Tachyon holds the CPU, a second core called the Media Engine, the graphics chip, 2 MB of video memory and 64 MB of RAM. On paper it beats the PS2 at clock speed and memory, and loses at drawing pixels and in video memory. So the port saves the CPU’s time and keeps every texture small

The CPU works. The GPU waits

Every frame the CPU used to write each drawing command one by one, while the graphics chip finished its share in 1.5 ms and sat waiting. Now each block of the city is written down once, as a ready list, when it loads from the Memory Stick. Every frame after that the CPU hands the graphics chip a whole block in one call

4.3 → 0.8 ms of CPU for 30 city pieces, with ready lists

The whole port so far: 131 sessions, 92 builds, 100+ hours of logged play

Sound moves to the Media Engine

The Media Engine is a second 333 MHz core beside the CPU. Sony let games use it only for its own codecs. With the open MIST library it now mixes all the sound, and hands it back to the CPU if it ever stalls

700–990 → 450–540 µs of CPU per audio buffer

A city in 53 MB

Everything is prepared for the Memory Stick when you build the game: textures optimized, roads baked, the level cut into 40 × 40 m cells. While you play, the cells around you stream in, one read each, on a thread of their own. Cells you drive away from are let go, to make room for the next ones

About 20 cells a second while driving

2 MB of video memory, no shaders

The frame and its depth take 816 KB of it. So the frame is 16-bit for the 480 × 272 screen, textures come in 16 or 256 colors, and lights and shadows are flat shapes drawn in one call

Textured shadows cost about 3 fps, now gone

Matched to the original, then made faster

More than 900 behaviors were compared one by one with the PS2 game. Every change is measured on a real PSP-2000 in an automatic tour of all 7 levels, and stays only if the numbers agree

Drop in your disc. The rest builds itself

No game files come with the engine. The builder converts everything from your own PS2 disc image and puts the game on your PSP