Porting a Core, DeMiSTified – Part 4 – 2021-03-03
(Before I start this installment, I should say that I have now released the Chameleon port of the NES core – I’m not going to delay the core just to talk about the process!)
So we have a project file for the MiST version of the core, and we need to create project files for other platforms. My scripts and Makefiles will produce these files, so what I need to do is extract a list of components from the .qsf project file for MiST.
Continue readingPorting a Core, DeMiSTified – Part 3 – 2021-03-01
When an FPGA core is a self-contained standalone project with only one target board, managing the project from within the FPGA vendor’s IDE works fine. However, once there’s a significant amount of shared code between projects, or you’re building for multiple targets, things get more tedious,
EightThirtyTwoDemos currently has targets for nine different boards, and there are another four within easy reach that I could add if I wished. There are nine demo projects in the repo, so I could have to rebuild as many as 81 projects when something changes. Loading each project, one after another, and rebuilding them manually would be ridiculously inefficient – a better solution is needed.
Continue readingPorting a core, DeMiSTified – Part 2 – 2021-02-25
The goal is to provide an environment in which a MiST core can be included as a submodule, thus porting the core to a new target board without making large-scale changes. To do this, we’re going to need a toplevel for each target board which maps the signals of MiST’s FPGA to board-specific resources.
Let’s take a close look at a MiST core’s toplevel…
Continue readingPorting a Core, DeMiSTified – Part 1 – 2020-02-24
There are many FPGA cores out there which could be ported to the Turbo Chameleon 64 cartridge. In some cases it’s just a question of somebody doing the legwork, in other cases it gets a little bit more involved – but can we do anything to make the amount of work required more manageable?
Long-time readers will know by now that I don’t ask that kind of question out loud unless I already know that the answer is yes!
Continue reading2021-01-30
I’ve just bought a couple of the ridiculously cheap DECA MAX10 dev boards from Arrow and one of the first projects I attempted to port to it gave me an error message I wasn’t expecting:
Error (276003): Cannot convert all sets of registers into
RAM megafunctions when creating nodes. The resulting number
of registers remaining in design exceeds the number of
registers in the device...
Hmmm, OK, what’s going on here? For some reason the ROM in my project isn’t getting recognised and implemented as initialised block RAM – what gives?
Continue readingThe EightThirtyTwo ISA – Part 23 – 2021-01-22
It’s been some time since I’ve made any significant changes to the EightThirtyTwo ISA, CPU or compiler backend, and this is mostly because I’ve been busy using it in real projects.
EightThirtyTwo’s original purpose, apart from the obvious learning exercise, was to be the supporting CPU in the AGA Minimig core for the Turbo Chameleon 64, and it’s performed this function quite nicely: it’s significantly smaller than the secondary TG68 used in the ECS core, and somewhat smaller than the OpenRISC cores that were used in some other Minimig variants, while using fewer memory blocks due to its logic-based register file and reasonably good code-density.
Nevertheless there are always bugs to be fixed and improvements to be made.
Continue reading2020-12-10
It occurred to me recently that there is a lot of history in the Minimig project, with many people making important contributions over the course of some 15 years.
It also occurred to me that as developers come and go, and new users encounter the latest Minimig cores without having seen what came before, there’s a real danger that some of that history will be forgotten.
Continue reading2020-09-22
I’ve just released an updated version of the MinimigAGA core for all three of my current target platforms – TC64 version 1, TC64 version 2, and MiST.
The core doesn’t have 100% feature parity between the three platforms, since the MiST has an onboard microcontroller to handle input and storage, while the Chameleon doesn’t. Having to implement an equivalent microcontroller in the FPGA makes some things harder – but other things easier.
For this reason, this time around the TC64 ports have a feature not yet available on MiST – experimental floppy drive sounds. To enable this, simply copy the drivesnd.bin file onto the SD card. If you don’t like it, just delete the file again – there isn’t (yet) a way to turn it on and off from the menus.
Other changes this time include the addition of a very basic LED Audio filter implementation – not accurate, but just good enough to make the going-through-tunnels sound effect in Lotus II work, and Slingshot on Atari-Forum has put some hard work into debugging the CPU core, and found an issue with stack frames which was preventing certain Graftgold games from working in ‘020 mode. His fixes to the CPU are included.
I’ve also made some timing tweaks on all three platforms so that all of them build with clean timing reports.
Turbo Chameleon 64 users can find the latest version of the core here
MiST users can find the latest version of the Minimig core at the official MiST binaries repository.
2020-09-12
After porting the MiST’s Minimig core to the Turbo Chameleon 64, I spent happy few weeks adding extra features including, most notably, RTG support. A number of people have kindly supported me in this endeavour, both directly via PayPal and also on Patreon – and I’m very grateful for this support.
None of this would have been possible without building upon the MiST’s AGA core, though, so it seems only right that I should port my improvements back to the MiST.
Continue reading2020-07-12
If it’s seemed quiet here lately, that’s because I’ve been hard at work improving the Turbo Chameleon 64 ports of the Minimig core.
The two main features added since the last release are an experimential implementation of the Akiko Chunky-to-Planar converter which can be used by a handful of games to increase video performance, and an experimental P96 retargetable graphics driver.
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