exorsim VS yamaha_dx97

On the 6800/6809: don't forget to look at the Fairlight CMI and the Qasar M8 developed by Tony Furse: the sampling synthesizer that was the sound of the 80s.

This past summer, Tony has been retrieving his 8-inch Motorola Exorciser floppies. He encouraged me to work on my Motorola Exorciser emulator- it now emulates a 6809 version of the Exorciser:

https://github.com/jhallen/exorsim

(check out the long discussions in the issues...)

I've been writing a lot of 8-bit assembler for the 6303, which is in the same processor family as the CPU in the TRS-80, which the author is writing code for (for this project in case anyone is wondering: https://github.com/ajxs/yamaha_dx97). I ran into the exact same issue. I wrote a MAME driver for the target platform, so I could test my builds on my development machine. Obviously that sped things up a lot. The MAME debugger isn't really a tool for unit testing, and can't really be easily instrumented, but I was able to write a lot of scripts for the debugger which would set up the breakpoints and system memory for an individual 'test'. Not quite unit testing, but as close as I could get cheaply.

I'm super impressed that someone has emulated the CZ-101's sound generation LSI!

Lots of people use MAME as an emulator to help reverse-engineering vintage synthesisers. I only recently discovered this too. Since most 80s synths were built mostly out of 'off the shelf' components, it's not too difficult to build a MAME driver which is capable of running the synth's firmware. The actual sound generation is another story though.

I wrote a MAME driver for the Yamaha DX9 while working on this project: https://github.com/ajxs/yamaha_dx97

I wrote a little bit about the project here in case anyone is interested: https://ajxs.me/blog/Hacking_the_Yamaha_DX9_To_Turn_It_Into_...

Very cool! I've been doing a lot of work reverse-engineering the firmware from Yamaha's 1980s synthesisers[0], all of which feature Hitachi 6303-series processors. The 6303 is Hitachi's second-source implementation of the Motorola 6803 architecture. I'd love to know how these devices were developed. I'm guessing a development platform like this would have been used by Yamaha. If anyone has any more information regarding development targeting the Hitachi 6300 series chips in the 1970s/1980s, I'd love to know!

[0] In case anyone is curious, my latest successful work is hacking the Yamaha DX9 to have the full DX7 feature set: https://github.com/ajxs/yamaha_dx97

If you don't mind swapping some chips, there's a project to bring out the full potential: https://github.com/ajxs/yamaha_dx97