> Obviously, at the time of the 80486, DDR didn’t exist, so SDRAM is a natural fit.
Neither are a fit, SDRAM was a Pentium/K-6 standard (PC66); the DIMMs ran faster than a non-OC'ed 486 bus, which ran at half the clock of the CPU. 486 "natural fit" would be FPM or EDO, if you wanted to be era-correct.
There were probably some off the wall 486 motherboards back then that supported SDR (post-1993...), but those would have been towards the very end of the 486 consumer life cycle. These did exist in the 486 era, where they had the option to run (or had an embedded) 386 using FPM while there was an open 486 socket and the option, but not requirement to run EDO.
Anyway, this is someone's project, so they can do whatever the heck they want.
It does, yes. But the DDR RAM available on the target board is DDR3 which is actually quite inconvenient for retro projects for a number of reasons.
Quite apart from the increased complexity, the most important difference is that there's a minimum speed as well as a maximum speed for modern DDR RAM, which means there's usually quite a narrow window of achievable clock rates when getting an FPGA to talk to DDR3.
I suspect that's why the author chose to use the DDR for video: It's usually easy to keep plain old SDRAM in lockstep with a soft-CPU, since you can run it at anything between 133MHz (sometimes even more) and walking pace, so there's no need to deal with messy-and-latency-inducing clock domain crossing.
Streaming video data in bursts into a dual-clock FIFO and consuming it on the pixel clock is a much more natural fit.
Silly question. Are there any 486-compatible small CPUs that could be embedded into a project instead of using an FPGA? Given that AMD, Intel and others have the ability to make 486-compatible processors currently, I would have thought you could just buy a CPU or SoC to run 486 code.
> Obviously, at the time of the 80486, DDR didn’t exist, so SDRAM is a natural fit.
Neither are a fit, SDRAM was a Pentium/K-6 standard (PC66); the DIMMs ran faster than a non-OC'ed 486 bus, which ran at half the clock of the CPU. 486 "natural fit" would be FPM or EDO, if you wanted to be era-correct.
There were probably some off the wall 486 motherboards back then that supported SDR (post-1993...), but those would have been towards the very end of the 486 consumer life cycle. These did exist in the 486 era, where they had the option to run (or had an embedded) 386 using FPM while there was an open 486 socket and the option, but not requirement to run EDO.
Anyway, this is someone's project, so they can do whatever the heck they want.
I hadn't heard of this board before, here's a link to a page on the manufacturer's site:
https://classic.sipeed.com/tangconsole
Doesn’t DDR just stand for Double-Data-Rate? So you implemented basic DDR on top is sdram. Not a bad approach, just wanted to point it out.
It does, yes. But the DDR RAM available on the target board is DDR3 which is actually quite inconvenient for retro projects for a number of reasons.
Quite apart from the increased complexity, the most important difference is that there's a minimum speed as well as a maximum speed for modern DDR RAM, which means there's usually quite a narrow window of achievable clock rates when getting an FPGA to talk to DDR3.
I suspect that's why the author chose to use the DDR for video: It's usually easy to keep plain old SDRAM in lockstep with a soft-CPU, since you can run it at anything between 133MHz (sometimes even more) and walking pace, so there's no need to deal with messy-and-latency-inducing clock domain crossing.
Streaming video data in bursts into a dual-clock FIFO and consuming it on the pixel clock is a much more natural fit.
so this will run half life 2 if I'm not mistaken?
Silly question. Are there any 486-compatible small CPUs that could be embedded into a project instead of using an FPGA? Given that AMD, Intel and others have the ability to make 486-compatible processors currently, I would have thought you could just buy a CPU or SoC to run 486 code.
I'm guessing the ITX-Llama is far less affordable next to reusing a "generic" FPGA retrogaming board.
I miss Intel's Quark chips. Tiny, cheap, and Pentium enough.
486? If it has VLB, it can play DOOM well!