Sorry for the lack of news on the Rev2 of the cumulus for the last month, différents problems on my side slowdown me a lot, and I've run into a large number of problem on the current design of the Cumulus that led me to reconsider how the rev2 will be.
Unfortunately I will not be able to provide a universal firmware for existing cumuluses and the Rev2, the hardware differences will be too high, but on the other end, we will win new functionality for the Rev2.
The Rev2 is going to be between the original Cumulus, and my project StratoCumulus, not all fonctionality will be here of course, but most of the important concerning the floppy will be there, plus maybe a few bonuses.
Here the list of changes:
- Screen will change, not in resolution or size, but the current used one is an old part, hard to source and mount
- The CPLD will change, to a higher end one (more block inside, so potentially more logic in it)
- The Microcontroler will change too, I'm going to change to a TI Tiva, an ARM cortex M4 chip. More processing power, more memory, more IOs, easier tu program, ...
- I will remove the EPROM and put SRAM in place, the idea is to store the ROM you want to use in the SD card, but don't worry there will still be a ROM hidden in the CPLD, so the cumulus will be able to let the oric boot without an SD card/ROM like if the floppy drive was not connected, or in the Jasmin way
- The SRAM will be at least of 16K, maybe a bit more, will depends on the price of components and how easy they could be sources and if more memory there will be, it will be accessible, no worries
- The CPLD will be upgradable from the microcontroller, so, gain of time during manufacturing, and being able to update it on the fly by you the end user, so no longer any excuse if there is a bug in there
- Some nice flashing indicators LEDs, because it's necessary...
What we will gain:
- Flexibility of the firmware development as we can upgrade both the CPLD and the uC
- The possibility to support Jasmin drives!
- Run any custom ROM
- Currently the SRAM chip I've selected is 32K, so maybe 16K more of SRAM paged along the existing overlay and ROM
- The whole design will be cheaper from my current estimations, which is a really good point!
- A direct access to the SD card could be imagined, but I will not work on that at first, and if some people want to do that, I will be happy to provide upgrade/support on the Cumulus side, to let this happen
(Maybe in Sedoric 5.0?
- Large part of the firmware will need to be updated/rewriten
- Same for the CPLD
- The "ROM" loading into the SRAM will be done by the Oric, so it will not be instantaneous, but it will not take hours too, and even maybe less than 1s, so I think there is no worries on there. I can also add some nice display for the impatients during loading ...
The first prototypes for the Rev2 will be an add-on card ("BoosterPack") for the TI Tiva LaunchPad (a bit like the "Shields" in Arduino terminology) so the prototype will be faster than when doing a full design. The will not be the final design unless it prove to be cheaper than doing the full thing.
So, we are getting closer to the final design of the Cumulus Rev2, need to finish the add-on card for working on prototyping the firmware, and see if it could work as expected and will try to keep you informed more often
(Funnily, the project architecture looks like other project I have..