JOTEGO

October Summary

Added 2019-10-31 15:38:25 +0000 UTC

Thank you for your support. This month work has been focused at gaining experience and developing IP. I chose two 16-bit games for this purpose:

- Bionic Commando

YM2151 for sound. I revised the JT51 core I wrote three years ago. Added clock gating and polished it a bit
i8751 MCU for protection. I found an open source IP and interfaced it with the core.
Brightness control (15-bit colour)

- Tiger Road

MSM5205 ADPCM sound. I wrote a core for this, the JT5205. I'm still testing it and will make it public soon.

Note that the four items above will be reused in future cores. JT51 and JT5205 will be used by more developers for their own cores. MSM5205 is needed for Double Dragon and System 16. YM2151 is needed for CPS1, System16 and Double Dragon. i8751 is used in more CAPCOM games and some System16 games.

Other IP

-Sprite repackaging: conversion of 8-pixel packets to 4-pixel packets so original sprite engine can be kept intact
-Sprite engine clock separated in three domains:
-DMA domain: to match CPU DMA timing as original board
-pixel domain: to match original pixel timing during video dumping
-draw domain: higher speed to avoid glitches from SDRAM reading. Does not affect game timing accuracy

-Added 15-bit colour support to framework (JTFRAME)

Beta Releases

-Bionic Commando: no sound and some glitches
-Tiger Road: no FX and some glitches

There will be a beta update over the weekend fixing the graphic glitches and Tiger Road FX. 1943 will likely be udpated too to fix sprite glitches.

As you see I'm trying to get IP done to get CPS1, System16 and Double Dragon close to reality. I'm borrowing PCBs for these systems and I'd like to return them soon!