Development Update/Trick Trap beta (Pocket) (Patreon)

No big announcements for this summer week but plenty of items to report.

Legacy Cores for Analogue Pocket

Analogue Pocket cores JTSLYSPY and JTFLANE are promoted to public as not issues have been reported on them. JTLABRUN core, compatible with Trick Trap/Labyrinth Runner, enters beta phase.

Maintenance

• Added support for screen flip to JTSHOUSE core. This is vital for tate CRT users and was a requested feature

• Fixed color merging problem in System 18/Super Hang-On

• Fixed music not stopping in Karate Champ VS after the fight started

• Color cartridges listed for monochrome NGP core

• Fixed problem with background color in CPS1's Three Wonders

Development Status

The plan for this week was to work on the NeoGeo Pocket color bug that prevents games from booting up but I started on Monday morning with what looked like one step away from having X-Men working on the JTRIDERS new core. That one step turned out to be more like a marathon.

X-Men is made of a M68000 CPU at 16MHz connected to same tile mapper chipset as TMNT, Aliens and Sunset Riders. Then, to the same sprite chipset as The Simpsons. It looked like it should be easy. Well it turned out that it plugs three RAM chips to the tile mapper, rather than two as all the other Konami games using the same chips. It took a couple of days to understand how the third RAM chip was used.

Then the sprites were equally confusing because the JT implementation of the chip is build to be compatible with a similar chipset used in Aliens and TMNT. One small detail of the implementation for Aliens was creating havoc for X-Men and it took another day to figure it out. Let apart all the usual shuffling of wires that Konami makes on each board, that adds more confusion.

Finally, the sound subsystem is different from all the other games. Apart from the usual YM2151 FM synthesizer, it has an 8-channel PCM sound generator that we had not worked on. Consulting with Furrtek, this IC is even more difficult to reverse engineer from die shots as the usual ones because it does not used a gate array approach. It is a regular ASIC with two layers of metal. This means that the digital cells inside cannot be looked up in a data sheet, but derived from the pictures. And the pictures are harder to make sense of because of the extra second metal layer. MAME has an implementation that has a few question marks in the source code. We will need to start from there and prepare for making chip measurements to solve the questions that will inevitably come up.

The good news is that X-Men is booting up correctly and it is even playable. Although PCM sounds are completely missing. The MRA files will not be published until PCM sound is ready. For MiST users, this game will not operate on the JTRIDERS core because of lack of enough internal RAM. The core will still be able to operate Sunset Riders and possibly Turtles in Time.

Turtles in Time currently boots up on JTRIDERS but sprites are not visible because one chip is still missing in the core. Furrtek is working on reverse engineering that chip. We may do a first version based on MAME documentation while we wait for Furrtek's work to be ready.

Schematics

Identified the pin names for Konami's 051962 in the Racing Force official schematics. JT schematics for X-Men, Vendetta and The Simpsons have been updated to use those pin names. X-Men schematics have also seen many small changes during the revision done for core development.

Remember that schematics are stored in:

• source in KiCAD format located in the cores/corename/sch folder in jtcores repository

• PDF format in the sch folder in JTBIN

Only schematics for published cores appear here. Other schematics may only be in the source code repository jtcores.