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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 processo

by ajxs 3y ago

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 https://github.com/ajxs/yamaha_dx97

Gordonjcp 3y ago
Most likely a "ROM emulator" that would plug into the ROM socket on the board, replacing it with a few kB of static RAM that you can pop stuff into from a computer. In the mid-90s I used an already pretty obsolete CP/M machine to drive one of those for developing Z80 embedded code. Although PCs were around - 386s and even early 486s if you had the money, they offered no real advantage because the editor, assembler, and linker only took about a second to load from floppy anyway. Given how much time I spend looking at 80x25 terminals I wonder why I put up with 20-second boot times now, over 30 years later.
- ajxs 3y ago
  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/ https://mygeekyhobby.com/2020/07/05/eprom-emulator/
  - Gordonjcp 3y ago
    What's wrong with it? If it gets as far as loading an OS you ought to be able to run the Forth disk. The big problem they have is sticking on filter calibration, because one or other of the 405x multiplexers fails.
jacquesm 3y ago
Hey Anthony, nice to see you're still at it! I really should get that chip to Ken... my todo lists have a habit of getting longer and longer...
- ajxs 3y ago
  Hi Jacques! That would be awesome. I've seen the inside of quite a few DX7s and DX9s now, but I still haven't come across a ceramic EGS chip yet. I've seen photos, so I know they exist. They must be super rare though.
  - jacquesm 3y ago
    Mine is plastic, the other one was ceramic. It will need dissolution in acid, which is one of the things that slowed this down because someone in the US will have to dissolve the casing.

by ajxs 3y ago

Gordonjcp 3y ago

Most likely a "ROM emulator" that would plug into the ROM socket on the board, replacing it with a few kB of static RAM that you can pop stuff into from a computer. In the mid-90s I used an already pretty obsolete CP/M machine to drive one of those for developing Z80 embedded code. Although PCs were around - 386s and even early 486s if you had the money, they offered no real advantage because the editor, assembler, and linker only took about a second to load from floppy anyway. Given how much time I spend looking at 80x25 terminals I wonder why I put up with 20-second boot times now, over 30 years later.

ajxs 3y ago
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/ https://mygeekyhobby.com/2020/07/05/eprom-emulator/
- Gordonjcp 3y ago
  What's wrong with it? If it gets as far as loading an OS you ought to be able to run the Forth disk. The big problem they have is sticking on filter calibration, because one or other of the 405x multiplexers fails.

jacquesm 3y ago

Hey Anthony, nice to see you're still at it! I really should get that chip to Ken... my todo lists have a habit of getting longer and longer...

ajxs 3y ago
Hi Jacques! That would be awesome. I've seen the inside of quite a few DX7s and DX9s now, but I still haven't come across a ceramic EGS chip yet. I've seen photos, so I know they exist. They must be super rare though.
- jacquesm 3y ago
  Mine is plastic, the other one was ceramic. It will need dissolution in acid, which is one of the things that slowed this down because someone in the US will have to dissolve the casing.