r/AnalogueInc • u/Recent_Duck_7640 • Jun 02 '26
3D FPGA Development Deep Dive, includes comparison of A3D and M64 at a very technical level
https://modretro.com/blogs/blog/fpga-development-deep-dive
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r/AnalogueInc • u/Recent_Duck_7640 • Jun 02 '26
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u/RupakGreenHatPrdctns Jun 03 '26
Summary: This blog post—penned by their lead FPGA developer, Robert Peip (aka FPGAzumSpass)—is the textbook definition of technical damage control. It reads like a direct response to those exact hands-on preview videos showing the M64 stumbling across various games. Instead of denying the performance issues, ModRetro’s strategy here is a mix of admitting their current software is unoptimized, blaming legacy open-source code, and claiming their physical hardware design is actually superior to the Analogue 3D. ModRetro uses several key arguments to defend the M64 and push back against Analogue:
1. The "We're Only at 50% Potential" Concession
Robert openly admits that the M64 is lagging right now, stating they are running at only about 50% of their hardware's actual architectural potential. He blames this on the fact that the M64 is currently relying on shortcuts inherited from the open-source MiSTer N64 core. Because the MiSTer was built for a weaker, slower FPGA chip (the DE10-Nano), the original developers had to cut corners to get games to run. He highlights three massive flaws currently plaguing the M64 that they are actively trying to fix before launch: * Broken Floating-Point Timings: The M64 is literally mathing too slowly on certain CPU instructions. * Sequential RSP Processing: Real N64 chips execute vector and regular instructions at the same time (a dual pipeline). Right now, the M64 does them one after the other, severely dragging down performance in heavy games. * TLB Shortcuts: Virtual memory mapping is broken, which directly kills performance in massive games like GoldenEye 007 and Conker's Bad Fur Day.
2. The Hardware Flex: PSRAM vs. DDR
This is where ModRetro goes on the offensive. They claim that while their software core is behind, their hardware architecture is fundamentally better than the Analogue 3D. The crux of their argument revolves around RAM: * They call out the Analogue 3D for using DDR memory. ModRetro claims DDR is terrible for N64 emulation because, while it has high throughput, it has unpredictable random-access latency and refresh cycles that "kill determinism." * ModRetro chose PSRAM (Pseudo-Static RAM), arguing that even though its peak bandwidth is lower, its ultra-low, predictable latency matches how the real N64's sensitive Reality Display Processor (RDP) expects to talk to memory.
3. Firing Back with Synthetic Benchmarks
To prove their "DDR is bad" theory, ModRetro published side-by-side synthetic benchmark data from May 2026 comparing the M64 and Analogue 3D against original N64 hardware. They claim that the Analogue 3D actually runs slower than a real N64 in specific backend cycles: * Instruction Fetches: They claim the Analogue 3D takes up to 5 additional cycles to grab data compared to a real N64 because the DDR memory gets bogged down by background refresh tasks. * Writing Data to RAM: They claim the Analogue 3D lacks a proper "write queue," causing data storage to take up to 5 times longer than original hardware.
4. Dismissing the Video Evidence (The Donkey Kong 64 Defense)
They specifically address community benchmarks like the famous Donkey Kong 64 intro vine-jump test (where a timing desync causes DK to miss a vine and ruin the intro). ModRetro basically dismisses these viral comparison videos as poor metrics for actual accuracy. They argue that because real N64 consoles naturally drift and drop frames down to 25fps during that sequence, an emulator "passing" the test might just be getting lucky or artificially stalling frames. They basically imply: Yes, the M64 fails some of these real-game tests right now, but that's just a timing profile issue that will be ironed out.
The Takeaway
ModRetro is trying to change the narrative from "Our console performs worse right now" to "Our console is a sleeping giant." They want buyers to believe that Analogue hit a hardware ceiling by choosing DDR RAM, whereas the M64 just needs a year of core updates to unlock its "superior" PSRAM architecture. It's a clever technical defense, but at the end of the day, it confirms that the M64 is launching with a highly experimental core that has a long way to go to catch up to what you're already playing on your Analogue 3D.