ZN-1 Update - CW/CCW Rotation + Fixes

New Features

• Added 90° clockwise and counterclockwise HDMI screen rotation for vertical TATE-mode titles.

• Tightened DDR memory timing to improve stability and reliability.

Fixes and Improvements

• Banked-ROM corruption fix

  • Removed a leftover debugging function that was unintentionally overwriting 32 bytes of banked ROM whenever a title was loaded.

  • Corrected the RayStorm R-3 checksum window.

  • Addressed stalls affecting Bloody Roar 2 and Heaven’s Gate.

• FRAM power-on initialization fix

  • Blank FX-1B and FX-1Z FRAM now returns 0xFF on first boot, matching the behavior of original hardware.

  • Corrects NVRAM and settings-related behavior in titles including G-Darius, RayStorm, and Fighters’ Impact.

• Tecmo CAT702 abort-loop fix

  • Corrected SNAC pulse-latency scaling.

  • Allows Tondemo Crisis and Tecmo World Cup Millennium to boot successfully.

• ZNMCU protocol fixes

  • Implemented byte-accurate protocol behavior.

  • Added the required unsolicited DSR pulse.

  • Corrected the timeout hang in Monster Farm Jump.

  • Addressed related boot failures affecting Tecmo titles.

• Bloody Roar 2 EEPROM initialization

  • Added the required AT28C16 index-9 preload across all regional versions.

  • The game engine now runs, although the asset loader still stalls.

• Bank-register masking

  • Corrected masking of Atlus and Taito FX bank-register bits [1:0].

  • Prevents watchdog-control bits from unintentionally affecting bank selection.

• FRAM read timing

  • Added the required FRAMWAIT timing behavior.

  • Corrected G-Darius operation on physical hardware.

  • Moved FRAM storage to M10K memory blocks to resolve FPGA resource-overflow issues.

• EEPROM timing and polling fixes

  • Added one read cycle to account for altsyncram latency and prevent stale sequential reads.

  • Added the AT28C16 data-poll busy gate for hardware-parity behavior.

Disclaimer

All product names, company names, project names, platform names, hardware names, game titles, logos, trademarks, registered trademarks, copyrighted materials, source code, and other intellectual property referenced in this post are the property of their respective owners.

This includes, but is not limited to, MiSTer, MiSTer FPGA, MiSTerFPGA, Analogue, Analogue Pocket, openFPGA, MAME, The MAME Project, GitHub, Sony, Sony Computer Entertainment, PlayStation, ZN-1, ZN-2, Namco, Namco System 11, Namco System 12, TPS, G-NET, Taito, Atari, Capcom, Arika, Takara, Tecmo, Video System, Eighting, Raizing, 8ing, Takumi, Success, Moss, Warashi, Mahjong Kobo, Metro, Enix, Jordan, I.T. Planning, Atlus, and Acclaim.

Referenced game titles include RayStorm, Bloody Roar 2, Heaven’s Gate, G-Darius, Fighters’ Impact, Tondemo Crisis, Tecmo World Cup Millennium, Monster Farm Jump, and Psychic Force. All associated characters, artwork, audio, game data, regional versions, hardware designs, software, and derivative works remain the intellectual property of their respective rights holders.

References to FX-1A, FX-1B, FX-1Z, CAT702, ZNMCU, SNAC, HDMI, DDR, FRAM, EEPROM, AT28C16, M10K, altsyncram, FPGA implementations, emulation behavior, source-code repositories, hardware specifications, software cores, compatibility research, and related technologies are provided solely for identification, technical documentation, commentary, interoperability, preservation, educational, and research purposes.

The use of any names, titles, trademarks, or technical materials does not imply sponsorship, authorization, endorsement, affiliation, or association with this post, its creator, the MiSTer project, or any related development project. No ownership of third-party intellectual property is claimed. No copyrighted game software, ROM images, BIOS files, encryption keys, or other proprietary game data is provided with this post.

All rights are reserved by their respective owners.

Support the FPGA Development Community

FPGA preservation is a community effort. This work is only possible because of the creators who paved the way forward. Consider supporting these talented developers and projects:

• MiSTer FPGA / Sorgelig — Patreon: https://www.patreon.com/FPGAMiSTer

• JOTEGO — Patreon: https://www.patreon.com/jotego

• FPGAzumSpass / Robert Peip — Patreon: https://www.patreon.com/FPGAzumSpass

• Coin-Op Collection / Atrac17 & pr4m0d — Patreon: https://www.patreon.com/atrac17

• Furrtek — Patreon: https://www.patreon.com/furrtek | Ko-fi: https://ko-fi.com/furrtek

• Pierco — Patreon: https://www.patreon.com/pierco

• Darren_O — Ko-fi: https://ko-fi.com/darreno

• Solal Retro Gaming — Ko-fi: https://ko-fi.com/solalretrogaming

• I Beceri Videoludici / rmonic79 — Patreon: https://www.patreon.com/IBeceriVideoludici | Ko-fi: https://ko-fi.com/ibecerivideoludici

• RodimusFVC — Ko-fi: https://ko-fi.com/rodimusfvc

• MacroFPGA — Ko-fi: https://ko-fi.com/macrofpga

• theypsilon — Patreon: https://www.patreon.com/theypsilon | Ko-fi: https://ko-fi.com/theypsilon

Please consider supporting the developers whose work helps preserve classic arcade and gaming hardware for future generations.

This list is provided as a community resource and is not an endorsement, sponsorship, or indication of affiliation. Support pages and project activity may change over time.

Source Code: https://github.com/XelaNotPu

Everything I publicly release will remain free and open source. Patreon is not about locking completed software behind a paywall. Instead, your support helps cover the time, equipment, development tools, testing hardware, hosting, and research required to keep the projects moving forward.