Jotego brings Volfied and Block Out to MiSTer FPGA

FPGA developer Jose "Jotego" Tejada has released a new batch of arcade cores for the MiSTer and Analogue Pocket, headlined by Taito's Volfied and Technos' Block Out. The update also includes a long list of bug fixes and a clever workaround for Sega System 18 hardware that refuses to sync with consumer CRT televisions.

Both new cores were contributed by developer Andrea and reviewed by the Jotego team. Volfied is a 1989 QIX-style game running on a derivative of the Rainbow Islands arcade board. It uses a Yamaha YM2203 sound chip instead of the YM2151 and relies on a framebuffer to draw its backgrounds. Two-player inputs are not supported yet.

Block Out is a 3D take on Tetris. It shares a sound subsystem with Double Dragon II and also uses a framebuffer. The Block Out core relies heavily on MAME documentation, and Jotego noted he does not plan to do further research on it. I am curious how a 3D puzzle game from the Double Dragon team actually plays.

Just play it four percent faster

The most practical addition in this update is extended CRT support for Sega System 18 games. Original System 18 hardware outputs at a low line frequency. Many consumer televisions simply cannot handle it. If your display drops sync when booting a System 18 core, Jotego implemented a manual override.

You start the core, open the MiSTer OSD, and press the OK button to cycle through eight different system speeds. Each press requires a five-second wait to see if the TV catches the signal. Jotego expects the 104% setting will work for most setups. The tradeoff is that the entire game runs four percent faster. The gameplay and the music both speed up. It works, which is the nicest thing I can say about a forced overclock.

A ROM patch for Chuka Taisen

The JTKIWI core previously supported Chuka Taisen, but the game was disabled due to rogue sprites appearing out of place. The team does not have a hardware-level fix for the visual glitch yet. Instead, Andrea contributed a ROM patch that simply prevents the dummy sprites from rendering at all.

The rest of the changelog covers a lot of ground across multiple arcade boards. Double Dragon and Double Dragon II now have a turbo option on the Analogue Pocket. OutRun received a CPU timing correction for bus arbitration between the main and sub processors. The update also squashes a permanent buzz sound in the CPS1 game Gulunpa and fixes a crash in the fourth level of Thunder Hoop. Other minor visual bugs were resolved in Run and Gun, Rainbow Islands, and 1942.

The update introduces tighter CPU clock control on Motorola 68000 games that use SDRAM for work RAM. Players using the older MiST or SiDi FPGA platforms also get a new video mode that displays scanlines without blending. SiDi128 users get a screen rotation fix.

Jotego funds his reverse-engineering work through Patreon, where beta cores are distributed to supporters first. Public releases eventually move to his GitHub repository. Replicating arcade boards at the silicon gate level takes time. Unlike traditional software emulators that approximate hardware functions sequentially, FPGA devices physically reconfigure their internal logic blocks to match the original arcade circuit designs. His JTCORES project encompasses hundreds of classic arcade titles, and the MiSTer community relies heavily on these updates to keep obscure hardware accessible.