STE DAC FPGA issues
Posted: Mon May 13, 2019 9:59 am
I have been contemplating when the FPGA MMU core etc gets tested with that with it being a STE core, a updated audio DAC circuit will be pretty simple in theory to add to the remake...BUT... When I started looking at the code, part of the DAC code is integrated into the video shifter
Technically we could replace the video shifter, but we was already thinking about using Smonson's FPGA shifter With hopefully the possibility of being able to add more resolutions etc. Which basically means a whole new can of worms with integrating the audio stuff as well.
I'm somewhat reluctant to change a lot of original chips all at once. But my current thoughts, if we started replacing half the system with Suska cores, that we are pretty much locking ourselves into basically rebuilding the suska itself. Basically we would end up with a STE machine based on suska, where we already know there are compatibility issues with the MMU core. All these course need to be tested thoroughly one by one by the community first.
I really would like to get the remake project as a STE machine, or at least get the DAC playback working, though it is looking like it would have to be a whole different motherboard. Of course the remake board we are already working on the FPGA blitter, and replacing the MMU & GLUE with the suska core so we can use SRAM and run the core at 32MHz or higher. This in itself will have issues in terms of compatibility when running at stock speeds, as the cores are not totally accurate yet, but Wolfgang would update the cores with the changes if we could tell him what to do and what to fix etc But that turns into a possible brick wall if Wolfgang is slow in making updates.
What really concerns me is this project is heading down the road that all other clones or emulators do, in that we lose original compatibility at stock speeds. I want to keep the STF as a fully backwards compatible machine, but of course we should be able to add enhancements without totally breaking the system..Which is slightly ironic as running high speeds basically does that anyway.. But at least currently we can turn these accelerations off and run at stock speeds and we can run all original software without issues.
So if any of you FPGA experts out there, can figure out if it is possible we can avoid replacing the shifter at this point, And keep all the DAC stuff internally on the "MMU" core (of course I know GLUE needs to be there as well)...
EDIT:
I emailed Wolfgang, he said it is possible to fully integrate the DAC system into the MMU... So at least that is one question answered.. Next problem is we need someone who can actually figure this out with the FPGA code...
Technically we could replace the video shifter, but we was already thinking about using Smonson's FPGA shifter With hopefully the possibility of being able to add more resolutions etc. Which basically means a whole new can of worms with integrating the audio stuff as well.
I'm somewhat reluctant to change a lot of original chips all at once. But my current thoughts, if we started replacing half the system with Suska cores, that we are pretty much locking ourselves into basically rebuilding the suska itself. Basically we would end up with a STE machine based on suska, where we already know there are compatibility issues with the MMU core. All these course need to be tested thoroughly one by one by the community first.
I really would like to get the remake project as a STE machine, or at least get the DAC playback working, though it is looking like it would have to be a whole different motherboard. Of course the remake board we are already working on the FPGA blitter, and replacing the MMU & GLUE with the suska core so we can use SRAM and run the core at 32MHz or higher. This in itself will have issues in terms of compatibility when running at stock speeds, as the cores are not totally accurate yet, but Wolfgang would update the cores with the changes if we could tell him what to do and what to fix etc But that turns into a possible brick wall if Wolfgang is slow in making updates.
What really concerns me is this project is heading down the road that all other clones or emulators do, in that we lose original compatibility at stock speeds. I want to keep the STF as a fully backwards compatible machine, but of course we should be able to add enhancements without totally breaking the system..Which is slightly ironic as running high speeds basically does that anyway.. But at least currently we can turn these accelerations off and run at stock speeds and we can run all original software without issues.
So if any of you FPGA experts out there, can figure out if it is possible we can avoid replacing the shifter at this point, And keep all the DAC stuff internally on the "MMU" core (of course I know GLUE needs to be there as well)...
EDIT:
I emailed Wolfgang, he said it is possible to fully integrate the DAC system into the MMU... So at least that is one question answered.. Next problem is we need someone who can actually figure this out with the FPGA code...