RISC OS SouthWest Show 2019






Available for Free

We are pleased to announce that as of the 4th of January 2018 the RISC OS Sound Module RDSP 0.40 is now available for:


Whilst RDSP is still under beta release, it is a provides a practical sound generation solution. Updates are planned to RDSP and a full version 1 release will be announced in due course. See the news section for more information.


RISC OS originally provided 8 channel 8 bit audio based on voice generators which were implemented via loadable operating system modules. These modules could play back 8 bit digital samples.

Subsequently, this audio system was upgraded to 16 bit audio implemented via shared sound.

However, no simple API was provided to load and play sound samples. Also, no synthesis capabilites beyond the voice generators were implemented.

This is why AMCOG Games have developed RDSP.

RDSP provides a modern sound solution, that reflects an up-scaled, up-lifted traditional computer synthesiser chip in the form of a 'SOFTWARE SYNTHESISER'.

RDSP comes with full source code and implements:

  • 16 voice 16-bit 44khz audio channels
  • 4 waveforms that can be adjusted, combined and modulated to produce a wide range of tones over a near 8 octave range.
  • 16 bit sample loading and playback
  • Integration with BASIC's SOUND and ENVELOPE commands
  • A digital delay effect
  • A digital chorus effect
Demo programs have been included.

NOTE: RDSP is currently at beta 5 and full release is planned for later this year.


RDSP has been tested on RISC OS 4 on Virtual Acorn and RISC OS 5 on Raspberry Pi 1,2 & 3 Beagleboard, Pandaboard, Cortex-A15 based systems, Titanium, ARM X6, RPCEmu and Virtual Acorn.


RDSP is free. It has also been included within the AMCOG Development Kit, please click Here for further information.

RDSP Features

  • NEW: As of version 0.40 : A chorus effect has been added
  • NEW: As of version 0.31 : Support for sound queuing for each channel.
  • NEW: As of version 0.26 : Support for stereo channel placement.
  • 16 sound channels
  • Waveform generation via phase accumlator oscillators that produce : Saw, Pulse-Wave-Modulation, Triangle, Pulse Noise as well as bitwise AND combinations of these waveforms.
  • Sample playback
  • XOR adjacent channel modulation to produce science fiction style and distorted sounds.
  • Just under an 8 octave frequency range
  • System wide 44khz 16 bit audio using shared sound
  • Sample and waveform modulation : Pitch, filter, amplitude and pulse width using a three stage envelope and ADSR envelope (1 per voice).
  • Digital delay effect
  • Integration with the SOUND and ENVELOPE commands
  • Partial legacy BBC Micro SOUND command compatibility
Contact Us Here