History

• 1983-1984: Wowed by enthusiastic magazine reviews and cassette tape demos (Electronic Soundmaker & Computer Music) of the recently released Yamaha DX7. But as a kid could only dream of playing with one.

• 1988: Discovered John Chowning's paper on FM synthesis in the University library and coded a two operator FM synth for the Acorn Archimedes in ARM assembler. Generated some very nice brass sounds! At the time having a 32-bit CPU, clocked at 8 MHz with 15ish GPRs was truly amazing, but there still did not seem enough computing resource to take the project further. In hindsight could have tried harder.

• 1995: Attempted to write a simulation of the DX7 in C for Linux. Have lost the source code, but remember that only a few of the standard Yamaha DX7 patches sounded anything like their name, most were unrecognisable. Included an ugly GUI full of sliders allowing control of all parameters. Lack of concrete data on the Yamaha algorithms, and no access to a DX7, physical or virtual, to try experiments, had lead to too many incorrect guesses around key details of the Yamaha OPS chip.

• 2020: Started a new software synth for MacOS and Linux, the JD-1! Had planned a range of different instrument models including a DX7. Project got bogged down progressing too many different instrument simulations at the same time. Completed some good research on DX7 firmware details (thanks AJXS) but the DX7 simulation never generated any sound.

• 2022: Stumbled across Ken Sheriff's blog on the DX7. This new source of accurate information has inspired a new attempt combined with a desire to switch my MCU module of choice to the RaspberryPi Pico. Hence this project, the picoX7.

• June 2023: Completed support for the RP2040 in Platform. picoX7 coding underway, mostly new code but some code borrowed from JD-1 and a previous attempt to write a software synth to run on an mbedLPC1768 (old Arm Cortex-M3 module).

• July 2023: picoX7 playable as an instrument and, with the same patch, starting to sound similar to Dexed.