When PCBWay stopped accepting PayPal last month I tried JLC and I have to say, their quality was impressive and the price was a little over half the PCBWay quote. Certainly worth shopping around with your gerbers. Might be an interesting write up comparing quality and price from the leading Chinese fab houses for the same board.
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I found the project on YouTube[1] and wanted to share it - but decided to find something that's text for HN, and in the rush to post I failed to check if the post is even complete. I should've posted the video instead.
I find first version https://github.com/petrmikheev/endeavour much more impressive. Dude somehow managed to get 100MHz DDR1 ram working on 2 layer board with no ground reference :o Its one of those things you only attempt when crazy or dont know any better. Anyone with EE experience will tell you its impossible, like flying commercial grade SoCs in satellites :) Mad lad.
This is very impressive. How did you learn to design a real computer, not the toy ones a lot of people made? I read part 1 and part 2 and looks like you just “thrown in” Ethernet and other stuffs and it was done. Really hope to learn from the process, thanks!
This is really cool and impressive... but relatedly...
Has anyone figured out what the minimum specs for Quake are?
I feel like the first thing everyone does with a computer is to determine whether or not it can run quake, and I'm just wondering what the like, most simple computer that could exist is, that could run quake?
You can find a lot of discussion about what the minimum specs for Quake are. Famously, it needs a decent FPU, and the Pentium was a convenient early CPU with a decent built-in FPU. It was significantly faster than a 486.
…But people have managed to run Quake on the 486.
And the myth people tell about Quake is that it killed Cyrix, because Quake performance on Cyrix was subpar. But was that true? And if it was true, was that because the Cyrix was slower than a Pentium, or was it because the Quake code had assembly that was hand-optimized for the Pentium FPU pipeline?
Anyway. “Most simple computer that could run Quake” is probably going to include a decent FPU. If you are implementing something on an FPGA, you can probably get somewhere around 200 MHz clock anyway. At which point you can run Quake II.
The Cyrix story is actually well-documented. Quake's software renderer used hand-optimized x86 assembly with FPU instruction sequences specifically tuned for the Pentium's pipeline. Cyrix processors had a different FPU execution pipeline that stalled on those specific instruction orderings — the issue wasn't raw FPU performance, it was that the Pentium-optimized code ran slower on Cyrix than straightforward C code would have. It was hand-optimization that made things worse, not better, on a competitor's hardware.
The timing was brutal for Cyrix. This was right when "Intel Inside" was becoming a meaningful consumer brand signal, and game benchmarks were becoming the primary way consumers evaluated CPU purchases. Quake wasn't just a game, it was the benchmark everyone ran at CompUSA to compare machines. Being demonstrably worse at Quake, regardless of the cause, was a marketing catastrophe.
The real floor for running Quake is basically "does it have a hardware FPU." The 486 DX (with FPU) could do it at low resolution and low framerate. The 486 SX (no FPU, software float emulation) was genuinely painful. The Pentium was the first CPU where it actually felt good.
My perspective from being a teen doing lan party stuff at the time: Quake ran slow on them, but it was far from the only thing that ran slow. Cyrix was well understood to be the value brand for general office apps and such, but not up to it for more demanding computing, and for having random compatibility issues here and there.
Ultimately what killed Cyrix is they just couldn't offer enough of a discount vs intel to matter, especially with all the lock in stuff intel was doing with Dell, Gateway, etc.
Intel Inside was a successful marketing campaign as well. If you were around back then I bet you can imagine the jingle/chord immediately.
I had a Cyrix 6x86 when Quake first came out. My disappointment at how poorly Quake ran on it was significant, especially because pretty much every other game at the time ran well on the Cyrix. The FPU performance in Quake was doubly handicapped on the Cyrix: not only was its FPU slower than the Pentium's to begin with, Quake's code was indeed hand-optimized for the Pentium's FPU pipeline. Fabien Sanglard's writeup of Michael Abrash's optimizations for Quake goes into great detail: https://fabiensanglard.net/quake_asm_optimizations/
Yes but also no. The problem with fixed point arithmetic is a lack of dynamic range compared to floating point. Floats are great at representing both large numbers with limited precision and small numbers with high precision, but with fixed point you have to make a choice based on which kind of number you're trying to represent. Meaning you need to use a mixture of 8.24, 16.16 and 24.8 fixed point types (and appropriate conversions) depending on the context of the calculations that you're doing.
It's possible to write a game engine with that limitation, but there's no easy natural conversion from Quake's judicious use of floats to a fully fixed-point codebase. You'd have to redesign and rewrite the entire engine from scratch, basically.
I want to look at this from a different perspective… a single-precision floating-point multiply is pretty simple, no? 24x24 bit multiply, which is about half as many gates as a 32x32 bit multiply.
Maybe I would prefer to rip out the integer multiplication unit first, before ripping out the FPU.
The PS1 doesn't an FPU but got a version of Quake 2, so it's possible. That said, it was somewhat different from the PC version, so it could be argued that it's not the same game.
I can't speak on Quake, but I was a level designer on the failed effort to port Unreal to PSX.
My understanding from talking to the coders at the time was that Unreal's software renderer was a huge advantage as a starting point. They were able to reuse a lot of the portal rendering stuff as setup on the R3K cpu, but none of the rasterization. That had to go to the graphics core, which was a post setup 2D engine that in addition to the usual sprites, could do tris and quads.
We had a budget of about 3k polygons post clipping, and having two enemies on screen would burn about half of that. The other huge limit is the texture cache was tiny, so we couldn't do lightmaps. Our lightning was baked in at vertex level and it just was what it was.
I imagine the situation with Quake was comparable. The BSP stuff would carry right over, but I can't imagine they got lightmapping proper working at the time. They'd also need some sort of solution for overdraw, as Quake's PVS was a lot more loose than Unreal's portal clipping.
The PS1 version uses a custom engine based on technology built for the game Shadow Master, the previous title by Hammerhead Studios. It was a technical tour de force for the original PlayStation.
I honestly don’t remember what the frame rate was, but it definitely improved when I upgraded to a Pentium 100. I distinctly remember a buddy giving me some RAM (2x4MB) which allowed me to play on the 486. I was so happy!
The DX2s _were_ a significant improvement over the 486DX, but I’ll admit, I might be remembering the excitement of getting to play Quake at all! The framerate may have been 15-20 fps and I just dealt with it,
The minimum requirements, on the box, were apparently Pentium 75Mhz. 8MB (DOS), or 16 RAM (WIN95).
As other had said: the only 'deal breaker' here is FPU.
Q1 is playable but not on any modern understanding of that word on a system with Am486DX4/100 with 16MB RAM and S3 Trio64V+. You can disable sound effects for a couple FPS more.
Mostly you would be fine because the level design in Q1 heavily tends to the closed spaces and corridors with only a glimpses of the outside and a rare halls and caverns. That being said the Necropolis would be a test of strategic thinking for turn-based FPS and Ziggurat Vertigo is unplayable.
Quake 2 was the one with the clever approximate inverse square root code, right? I wonder (especially since there’s an instruction nowadays to draw inspiration from), can you implement it “in hardware,” so to speak?
DDR3 traces need to be length matched, because at 800MHz (the slowest "standard" rate, though I think you can drop to 666MHz safely) the value on the pins is changing every 1.25ns, and having traces of different lengths means you probably won't see the right values on all the pins at the same moment. Length matching produces the squiggles.
The diagonal orientation of the DDR3 chip and corresponding diagonal traces I suspect is a choice made by the author to ease the layout process - it's more likely that is hand laid out to get traces of somewhat similar length with a minimum of fuss, followed by a length matching tool. A non-standard orientation can cause issues with pick-and-place machinery, which usually will handle 90 degrees fine, and _often_ 45 degrees fine, but (AFAIK) _rarely_ anything else, but that's not a problem for the author because he's assembling it himself. A diagonal IC also usually results in wasted space, which you can see in the empty areas of the resulting board. A 90 degree orientation may have allowed for a few more decoupling capacitor banks, but since his board works, who am I to sit here and judge?
Why would you be a weirdo? Two-panel is the only somewhat sane way to navigate the file system, though I still try to Ctrl+\ and need to remember to Alt+S and only then to type the search pattern.
I have the album on my phone. When I get called in to put out a fire and save the day, I like to put on March Of The Stroggs in the car when arriving at the destination. It's a great soundtrack for two reasons - the first one is sweet, wasted youth and the second is it's a great soundtrack.
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