yamaha_dx97 VS EPROM-EMU-NG

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

I actually used one of these things[0] during development of the DX9/7 firmware mod. I like your Mirage tools by the way! I've actually got a very battered Ensoniq Mirage I picked up for free that's badly in need of some maintenance. If I can get that running I'd love to give your firmware a try!

[0] https://mygeekyhobby.com/2020/07/05/eprom-emulator/

Well, the static RAM that the EPROM emulator uses has an access time of 55 nanoseconds. Here's a better description of the hardware.

To use an arduino you'd need to design debug and code something like this specifically to emulate the expected EPROM in the poly-800. An arduino isn't pin-compatible, you can't just shove one in there. Guessing based on the size of the dump file, it's 8k x 8bit, or 64kbit, so probably either 24 or 28 pins? Kind of boils down to how valuable you consider your own time and how much you want to spend to build something for what is basically a one-off, because nobody really needs that.

I’ve recently started using the EPROM-EMU-NG to replace the EEPROM with a second SRAM chip, along with an Arduino Nano and some shift registers to be able to program the SRAM from your development station. It holds RST low on the 6502 while it’s doing its work, and can be powered by either USB or the EEPROM power rails.