@tynemouthsw.bsky.social, I thought you might be interested in this approach with regards to your Mini VIC project. It's an alternative to using FPGA. The software emulation would obviously need to be spot on, but if this ends up working for the Oric ULA, then why not the VIC 6560/1?
Always good to have lots of options. For the Mini VIC, I could give a list of VIC replacements it has been tested with and let the buyer choose.
Unless there is a clear winner that is cheap and 100% successful and I can buy those in and ship them with the kit, or integrate directly into the board.
I'm tempted to try this RP2350 approach for the VIC chip myself. It has at least been added to my growing list of possible retro projects, so maybe one day.
I do these projects as open source and my own enjoyment so if anything I do is useful, feel free to fork or copy parts. Nothing published yet as this is really early concept stage.
Looked up the VIC20 555 reset time, which seems to be measured in seconds. That's good news for an RP2350 based approach. On the Oric ULA I think more trickery will be needed, with its RC based reset circuit measured in milliseconds.
The reset circuitry on the Oric can be a bit unreliable. If I was doing an Oric replacement, I would drive the reset line low until the new ULA was ready. http://blog.tynemouthsoftware.co.uk/2016/05/oric-1-repair-part-1-reset-circuitry.html
When I say "if I was doing an Oric replacement", of course I mean "I am doing an Oric replacement".
Comments
Unless there is a clear winner that is cheap and 100% successful and I can buy those in and ship them with the kit, or integrate directly into the board.
http://blog.tynemouthsoftware.co.uk/2016/05/oric-1-repair-part-1-reset-circuitry.html
When I say "if I was doing an Oric replacement", of course I mean "I am doing an Oric replacement".