Coin-Op Collection Presents: DECO-6280 (Act Fancer: Cybernetick Hyper Weapon)

Today's release for the Analogue Pocket and MiSTerFPGA platforms is the first entry on the DECO6280 platform. Act-Fancer is a horizontal scrolling run-and-gun built on Data East's 8-bit custom hardware, an evolution of the DECO-8 board behind Psycho-Nics Oscar and Cobra Command that moves the main processor to a HuC6280, the same hardware family behind:

Bloody Wolf (1988)Act-Fancer: Cybernetick Hyper Weapon (1989)Trio The Punch: Never Forget Me... (1989)

This post covers a technical overview of Act-Fancer on DECO6280, the in-house CPU and sound IP the platform is built from, and the game itself.

Overview:

Act-Fancer runs on Data East's 8-bit hardware (PCB DE-0317-1), driven by a single HuC6280 at 7.16 MHz. Where the earlier DECO-8 boards used a Motorola MC6809E for the main CPU, this board moves to the HuC6280, the part Data East packaged as its Custom 45. A 6502 sound CPU at 1.5 MHz manages the audio system, which pairs a YM2203 (OPN) at 1.5 MHz for FM and PSG output with a YM3812 (OPL2) at 3 MHz for additional FM synthesis and an OKI M6295 at 1.024 MHz for ADPCM samples. Audio output is mono.

The video system outputs 256x240 at 57.44 Hz. Graphics are rendered by the same Data East custom ICs used on the DECO-8 boards: two BAC06 tilemap generators, one driving a 16x16 4bpp background and the other an 8x8 4bpp foreground character layer, and an MXC06 sprite engine for 16x16 4bpp sprites pulled from a DMA-buffered list. The display composites the three layers from back to front as background, sprites, and foreground. The palette holds 768 entries in RAM across the characters, tiles, and sprites.

Development Challenges:

Every processor and sound device on the Act-Fancer board is covered by in-house Coin-Op Collection IP. The main CPU, the sound CPU, and all three sound chips are Verilog cores, with the graphics handled by the BAC06 and MXC06 customs carried over from the DECO-8 work. Two of these are new for this release: x6280, the HuC6280 the platform is named for, and x3812, the YM3812 OPL2. The rest are cores already proven on earlier releases.

x6280: The HuC6280 is the part that defines the DECO6280 platform. It is an 8-bit CMOS microprocessor built on a 65C02-derived core with an integrated memory-management unit, a multi-vector interrupt controller, a timer, parallel I/O ports, and a six-channel programmable sound generator on a single die. Data East packaged it as their Custom 45 and used it as the main processor in place of the MC6809E that drove the earlier DECO-8 boards. x6280 is a fully synchronous, cycle-accurate implementation of the whole device: the 21-bit CPU body with its eight memory-page translation registers that map the processor's 16-bit address space across a 2 MB range, the ALU with the 6502 block-transfer operations, the interrupt and timer registers, the I/O ports, and the six-channel PSG with its waveform RAM, noise, LFO, and direct-D/A modes feeding a stereo mix. On Act-Fancer the board uses the HuC6280 purely as a processor, with VBlank wired to its first interrupt, so the core runs the CPU body and interrupt path while the integrated PSG goes unused on this title. The full device is in place for the platform's other boards.

x6502: The sound CPU is a plain NMOS 6502 running the audio firmware. x6502 implements it as an explicit per-cycle state machine with no microcode, where each state is one bus cycle and the bus outputs are registered a cycle ahead, covering all 151 documented opcodes across the thirteen addressing modes. Unlike Psycho-Nics Oscar, which gates its sound CPU behind the DECO 222 opcode encryption, Act-Fancer runs the 6502 unencrypted. It takes commands from the main CPU through a sound latch that raises its non-maskable interrupt, and its maskable interrupt is driven by the YM3812.

x2203 (YM2203): The YM2203, or OPN, supplies three four-operator FM channels and a three-channel PSG. x2203 is the same in-house OPN used across the platform, time-multiplexing a single operator datapath across the FM channels each sample period and summing the FM accumulator with the PSG output. On this board it runs at 1.5 MHz, and its FM and PSG outputs are brought out separately in the core so each can be mixed on its own.

x3812 (YM3812): The YM3812, or OPL2, adds nine channels of two-operator FM synthesis with the chip's selection of waveforms. x3812 is the in-house OPL2 LLE implementation, new for this release and running at 3 MHz on this board. It is the only device on the audio section wired to interrupt the sound CPU, so it carries the timing the music engine runs against.

x6295 (OKI M6295): The OKI M6295 plays back the board's ADPCM voices, up to four at once, from a sample ROM. x6295 is the in-house implementation, developed by Pramod. On Act-Fancer it runs at roughly 1.024 MHz with its rate pin held high. The core reads its samples out of block RAM rather than the wide SDRAM path the graphics use, since the ADPCM stream is fetched one byte at a time and does not fit a cached wide-word read.

With the main CPU, the sound CPU, and the full audio section all standing on in-house IP, and the BAC06 and MXC06 graphics customs carried in from the DECO-8 boards, the entire Act-Fancer board is accounted for. The core was verified against an original Act-Fancer board.

Core Options:

The MiSTer core includes video settings for aspect ratio, vertical scaling and cropping, scandoubler effects, and H/V positioning and sync adjustments. The refresh rate toggle is disabled while the core is in development.

Audio settings provide separate OPN FM, OPN SSG, OPL2, and M6295 PCM toggles with volume control for each. Arcade dip switches are directly accessible from the OSD. Game settings include per-player auto-fire with adjustable rates, mapping options for Player 1 and Player 2, and a synced mapping mode that mirrors Player 1 to the Player 2 layout.

Cheats are accessible from the OSD. The set includes infinite credits, infinite lives, invincibility, and a group tied to the game's evolution system: an infinite evolution toggle, an infinite devolution-delay toggle, an evolution and devolution maximum, and a form select that locks the cyborg into any of its six evolved shapes.

The Pocket core provides auto-fire with per-button targeting and adjustable rates, and carries the same cheat set: infinite credits, infinite lives, invincibility, the evolution group, and the form select. Arcade dip switches available on Pocket are Attract Mode Sound, Lives, Difficulty, and Extend.

History, Gameplay, and Regional Information:

Act-Fancer Cybernetick Hyper Weapon was developed and published by Data East in 1989, released in Japan that May and was a steady earner in Japanese arcades, placing sixth on Game Machine's June 15, 1989 chart of the month's most successful table units.

It is the third entry in Data East's loose "Evolution Trilogy" after Darwin 4078 and Super Real Darwin, and the only one of the three built as a horizontally scrolling run-and-gun rather than a vertical shooter. J. Yamaguchi is credited as planner, with programming by Hisatada Ohta, Kazunori Ishiguri, and Toshiyuki Sakai. The soundtrack was composed by Azusa Hara alongside Hiroaki Yoshida, Shuji Segawa, and Tatsuya Kiuchi, all of Gamadelic, Data East's in-house sound team. Hara also scored Psycho-Nics Oscar and Cobra Command, the two DECO-8 titles this platform grows out of.

Players control SCI=VAX, a cybernetic weapon deployed against the synthetic creatures spreading from a crashed transport that carried a biological payload. The defining mechanic is evolution: blue orbs dropped by defeated enemies advance the cyborg through a chain of forms, each a heavier weapon loadout, up to its final shape. Taking a hit reverses the process, devolving the cyborg toward its base form, and the current form also decays on a hidden timer that red orbs can hold back. An 8-way joystick handles movement with two buttons for shot and jump. The game runs five stages, each with a mid-stage boss that doubles as a checkpoint and an end boss, closing on the infestation's core, Geagalze.

Updates:

Act-Fancer is the first DECO6280 release, and with the HuC6280 and the rest of the board now standing on in-house IP, the platform is ready for the titles that follow it. Trio The Punch is next, running on the same HuC6280 hardware and reusing the work done here. Bloody Wolf follows, and the additional IP it needs has already been stood up: where Act-Fancer and Trio The Punch use the OKI M6295 for ADPCM, Bloody Wolf uses the MSM5205, and x5205, the in-house MSM5205, is complete and ready for it.

Completing x3812 also clears a backlog beyond DECO6280. The YM3812 turns up across a number of platforms, and the same way x2203 unblocked the cores waiting on a clean in-house OPN, several finished releases have been waiting on a hardware-accurate OPL2 before they could go out. With x3812 done, those updates will begin to roll out.

Disclaimer: All product names, trademarks, and registered trademarks mentioned are the property of their respective owners. "Analogue", "Analogue Pocket", "MiSTer", "MiSTerFPGA", "OpenFPGA", "Data East", "Hudson", "Motorola", "MOS Technology", "Yamaha", "OKI Semiconductor", and all derivative works are trademarks, registered trademarks, or copyrighted materials of their respective holders. Use of these names does not imply endorsement or association with this post. All rights reserved to their respective owners. This post is for educational and research purposes only.