> 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.
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.
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.
Define "486-compatible." As far as I know even intel's newest cpus can run 486 era 16-bit stuff in hardware.
But, a plain answer: Via Eden boards. still use north/southbridge architecture, and are from the mid 2000's.
It's just modern Windows/Linux that have discontinued the ability. Or, perhaps you have 16/32 and 32/64 and are unable to do 16bit on 64bit machines- which still boils down to "operating system."
By far the biggest issue though is that even the Via Eden processor is significantly faster than a 486- and lots of software (especially games) from that era used no-op instruction loops for timing and timers. This results in games like The Incredible Machine's level timer running out in half a second or less.
Vortex86 is probably the closest thing to what you are looking for.
Any idea when Pixel86 is going to be available again or how/where to get an ITX-Llama system?
Intel did have a product like that but it's been discontinued: https://en.wikipedia.org/wiki/Intel_Quark
I'm guessing the ITX-Llama is far less affordable next to reusing a "generic" FPGA retrogaming board.
I hadn't heard of this board before, here's a link to a page on the manufacturer's site:
A review of sorts - https://youtu.be/ScwZwfS53dE
Ah that’s nice. Affordable FPGAs are always welcome.
I miss Intel's Quark chips. Tiny, cheap, and Pentium enough.
Didn't they have the F00F bug? (Thanks, I keep misremembering) How much more Pentium do you want?
No, the Quarks did not have the f00f bug, that would have been funny though.
I would love to see ancient tech fabbed out on modern processes.
What's the smallest SOC you could design to run DOOM? What power envelope would that consume (exclusing display/speakers/etc.) At that size and (optimized) transistor count, what speeds could we realistically achieve?
What would a massively-multicore (gpu-style with multi-hundreds or more of cores) one of these run like?
Every time I see a project like this, these thoughts run through my head.
486? If it has VLB, it can play DOOM well!
When you say "credit-card-sized," I expect the thickness to be as thin as a credit card, too. Isn't the Raspberry Pi credit card sized too?
so this will run half life 2 if I'm not mistaken?