Purpose-built emulation of the Telesensory Systems/Speech Plus Prose 2000/2020 speech synthesizer for modern NVDA.
The project does not embed or launch MAME. Its intended architecture is a small engine containing only the hardware needed by Prose 2000:
- Intel 8086 firmware execution.
- Minimal 8251 UART and 8259 interrupt-controller behavior.
- NEC uPD7720 speech-DSP execution.
- Serial DSP output capture as PCM audio.
- A small isolated host that streams 10 kHz PCM to an NVDA synth driver.
The source build expects a directory containing the standard prose2k ROM
set. The original firmware remains the property of its respective rights
holders and is not covered by the emulator source's BSD license.
A ROM-free standalone command-line renderer is also available for rendering Prose speech to WAV without NVDA.
The native engine boots the original 8086 and uPD7720 firmware, accepts serial
text and reconstructs the board's 12-bit DAC output. ProseHost.exe runs
outside NVDA and communicates through a bounded binary protocol. NVDA remains
responsive while speech is generated, and can cancel or replace the host if it
stops responding.
The add-on currently provides speech, pause, cancellation, Say All completion and NVDA audio-device routing. Rate, Pitch and Volume use the original Prose firmware controls and are exposed through NVDA. Its DSP scheduler enters the firmware audio routine at the synthesis loop's safe boundary, avoiding the timer race that corrupts sibilants.
The supplied firmware provides one English male voice. It does not expose selectable voices or variants; its supported user settings are Rate, Pitch and Volume.
The packaged add-on checks releases at https://github.com/OnjLouis/prose2000 once a day. A manual check is available from NVDA's Tools menu; network checks run outside NVDA's main thread.
SoundWave 1.2.1 and later can render Prose 2000 directly through an independent host process without altering NVDA's active synthesizer or global audio path.
Configure native with CMake and build the ProseHost target. The ROM-free
prose_cli renderer is available separately for command-line use and remains
useful for firmware and audio regression testing. It is not packaged in the
NVDA add-on. See
native/README.md for build and command-line usage.
MAME's tsispch.cpp documents the board memory map and ROM layout under the
BSD-3-Clause license. MAME currently marks Prose 2000 as not working and without
sound because its uPD7725 core does not expose the serial output and clock used
by the board's DAC. This project implements that missing path directly instead
of distributing MAME.
- The original Prose 2000/2020 hardware and firmware were developed by Telesensory Systems Inc. and Speech Plus. The firmware remains proprietary and is not covered by this project's BSD license.
- MAME's Prose 2000 driver, by Jonathan Gevaryahu with thanks to Kevin Horton, established the board memory map, ROM layout and hardware clocks used by this implementation.
- The standalone MAME compatibility shim is adapted from David Sexton's DoubleTalk PC project.
- The vendored 8086 core and endian helpers come from MAME and retain their original BSD-3-Clause copyright notices.
- Prose-specific emulation, DSP serial-output capture and NVDA integration were developed by Andre Louis with OpenAI Codex assistance.
The emulator and NVDA integration source are available under the BSD 3-Clause
License. See LICENSE for the full terms and retained attribution.