Expansion Port Sound Module Plus (EPSMPlus)

Description

PLACEHOLDER – IMPORTANT NOTES PLEASE READ

• This listing is a placeholder. EPSMPlus units have not been sold or made available yet. This listing is being used to gauge interest and allow customers to sign up for notifications when the EPSMPlus becomes available.
• Features have not been finalized. Planned features may be expanded, cut, or changed before release.
• Not much software currently makes use of EPSM functionality. The goal is to get these units into the hands of people writing homebrew, tools, music, and testing software so the EPSM can become more useful to a wider audience.
• Please note that the NES Expansion Port must be available and uncovered for this product to work. The plastic cover over the Expansion Port must be removed by the end user.
• A Famicom version is also being considered. If you are interested in a Famicom version, please register your interest here.

Expansion Port Sound Module Plus (EPSMPlus)

The Expansion Port Sound Module Plus, or EPSMPlus, is a planned enhanced version of the Expansion Port Sound Module. The goal of the EPSMPlus is to combine the audio features of the EPSM with additional Expansion Port functionality inspired by the NES Expansion Bridge.

Planned EPSMPlus Features

• Cable connector to connect a Famicom Disk System RAM Adapter through the NES Expansion Port for use with the Muramasa Disk System Cartridge. Cable not included.
• 100k potentiometer to control Expansion Port audio mixing levels.
• Famicom 15-pin Expansion Port.
• Bluetooth support for wireless controller functionality.

Expansion Port Sound Module (EPSM)

The Expansion Port Sound Module, EPSM for short, is a device made for the NES Expansion Port, a port that was included on the NES but almost never used.

The device started with the idea of making something useful for that unused port. The basic idea is to add more audio capabilities to the NES without requiring expensive audio hardware in each individual cartridge, while also making it possible to listen to existing cartridges with expansion audio.

On an unmodified NES, game cartridges with expansion audio output that audio into the cartridge slot, but the NES does not normally mix that audio into the system output. The EPSM helps solve this by forwarding supported expansion audio through the Expansion Port.

The EPSM also adds new audio capabilities for future homebrew support. The EPSM would have been possible to make as early as 1985, though in a bulkier version, since the slimmer version of the chip used in this design did not exist as early.

EPSM Features

• Genuine Yamaha YMF288 FM Synth Chip
• Adds 15 new sound channels to the NES for future homebrew support
  • 3 square wave channels, also capable of noise
  • 6 FM synth channels with hard-panning stereo support
  • 6 rhythm channels featuring 6 different ADPCM drum recordings with hard-panning stereo support
• Forwards expansion audio from supported game cartridges
  • Original Famicom expansion audio games with compatible adapter
  • PowerPak
  • EverDrive N8 or EverDrive N8 Pro
• 2 different addressing modes
  • Direct / mapper-assisted
  • Fallback mode
• 3.5mm jack for stereo output

Cartridge Support

Direct mode addressing requires an EverDrive N8 Pro with this mapper pack for EPSM support. EPSM-specific cartridge boards using direct addressing mode are planned. You can sign up to be notified of the first planned cartridge board here.

Source and Support

Please note that although this is an open source noncommercial project, Muramasa Entertainment has received permission to manufacture the EPSM from Perkka, the creator of the EPSM. Support is limited, so before purchasing, please check the Github page for more information on the product. You can also ask questions on the NESDEV Discord in the #chiptuning or #hardware channels.

Example

If you would like to hear examples of what is possible, you can listen to this playlist from how2Bboss here.