The DooM-chip: no CPU, no opcodes, no instruction counter

Some of the ultra-cheap "battery portable handheld games" (https://en.wikipedia.org/wiki/Handheld_electronic_game ) which are still produced today may have such ASICs, although I suspect a lot of them are actually a 4 or 8-bit CPU with a mask ROM.

artiscode• 6 years ago

Amazing project! Next step: custom silicon ASIC, the Doom arcade machine

aortega• 6 years ago

Nice work. However, a state machine "state" could be seen as an instruction counter.

sylefeb6• 6 years ago

Author here - Thanks! You are absolutely correct there are several state machines (vga, sdram controler, framebuffer, texturing, divider, renderer, etc) and each with an active state index. The renderer is the biggest one with 69 states.

I agree the state index can be seen as an instruction counter, albeit into very specialized instructions: there are no two same instructions in a given module, each is uniquely implementing a precise subpart of the algorithm. Also the states decide the flow and select the next state, there is no list of instructions you could program or re-arrange. So I wanted to capture this idea that the algorithm is completely embedded into the circuit itself, which is not capable of doing anything else.

There is definitely a very interesting trade-off between a general instruction set and an extremely specialized state machine like here - combining both seems promising?

floppy1235• 6 years ago

Question is: How far will you go, fully playable level?

tenebrisalietum• 6 years ago

This contributes to the timelessness of Doom.

Doom pretty much has been ported to everything with a CPU, like Linux. Heck, you can even search for JSDoom and get a few results. There's even a RISC-V port (RISC-V emulator included: https://github.com/lcq2/risc-666)

It will be interesting if it progresses past simply drawing the level, e.g. if you can actually play it.

Then Doom won't even need a CPU to exist.

anthk6• 6 years ago

Meh. I can play Minizork and Curses (version 3) on a:

- Monochrome GameBoy and compatibles.

- PDAs, nearly all of them.

- That intelligent pen which parsed everything you wrote.

- KA10 with Tops20 with dfrotz.

- GBA/NDS/PSP/Android/ioS... anything portable.

- Everything SIMH emulates, or nearly everything.

- All of the 8/16/32 bit minicomputers.

- Any OS with a gopher client. Even Nethack/Telnet may work with a dumb wrapper.

- A PostScript printer with a crafted input.

- Over telnet/ssh/irc... name a text protocol and you will be able to play it.

phkahler2• 6 years ago

I'd like to talk to you about ray tracing. Have an algo that would be incredibly fast in hardware. I think I may have tried integer math at one time.

Keyframe• 6 years ago

What is old is new again: https://www.businesswire.com/news/home/20050614005701/en/ART...

phkahler2• 6 years ago

> The AR350 ray-tracing chips process 66 million ray-triangle intersections per second per core.

I was doing 1.5 million Ray's per second against scenes with 100,000 polygons back then on an AMD64.

Acceleration structures are everything. Traversing them quickly and having dynamic updates is hard.

Vekz• 6 years ago

This is the future of hardware. Specialized chips baked for a focused application.

speedgoose• 6 years ago

So JavaScript processors?

WatchDog• 6 years ago

The future sure sounds a lot like the past, given that everything, even toasters have CPU's in them these days.

corysama• 6 years ago

http://www.cap-lore.com/Hardware/Wheel.html

We’re currently rolling around back to a new era of lots of specialized chips.

duskwuff• 6 years ago

Toasters are moving back to ASICs too:

https://www.diodes.com/assets/Datasheets/PT8A2514A.pdf

castratikron• 6 years ago

There are Super Nintendo games like Star Fox that had a second accelerator chip on board. But it would still be cool for the game to be the computer and exist in custom silicon. Development would be super slow of course but the result would literally be the best it could be.

Wonder if the advantage would be worth it. Is anyone trying?

moring• 6 years ago

I read somewhere that the chip used in Star Fox (SuperFX) is less an "accelerator" but rather "becomes" the main chip because it hogs the main bus, so the SNES's own CPU can't really do a lot. OTOH the SuperFX is not really a "game in silicon" but just a better CPU that has built-in fixed-point arithmetic including multiply/divide. All this is just from memory, so please take it with a grain of salt.

mhh__2• 6 years ago

Future? Most high end T&M gear will have an ASIC in it.

FPGAs are already very very prevalent. They aren't too common for hobbyists because although the transistor density in an FPGA has increased the pricing hasn't really followed suit a la regular CPUs - that and the tooling is often comically 1990s

nabla9• 6 years ago

I bet 2000 years from now Doom is belongs to canon like Iliad. It's of the timeless classical epics among the oldest extant works from the early silicon era. Doomguy is mentioned with Gilgamesh and Odysseus.

hiccuphippo• 6 years ago

Funny, I thought the same of Xena back in the 90's. What about Kratos or Spiderman?

andrewflnr• 6 years ago

Spiderman is another decent bet. He obviously has some long-term staying power.

kick3• 6 years ago

Why? DOOM was a technical achievement, sure, but it has little in the way of story; it didn't even attempt the whole "trying to tell a story without words" thing common in video games of today. It's certainly not an epic.

If they wouldn't have released source code for it in 1997, who would actually be thinking of DOOM today in terms of anything but "Wow, that had pretty cool tech!"?

I could kind of understand the story appreciation for DOOM 3, because it at least had a story, but DOOM?

anthk6• 6 years ago

Most games except adventures and text adventures have a worse script (lit wise) than any average episode of X-Files/The Outer Limits and so on.

Heck, Half Life looks like a -mediocre- episode of The Outer Limits.

icelancer• 6 years ago

Doom's story is of id, not Doomguy.

derefr• 6 years ago

If they wouldn't have released source code for it in 1997, who would actually be thinking of DOOM today in terms of anything but "Wow, that had pretty cool tech!"?

I mean, no, but that event is the point. I don't think the parent is asserting that DOOM the game will be remembered in the classical canon. It's the codebase that belongs there!

sylefeb6• 6 years ago

Doom has had an immediate huge impact in its time ; even before the source code got released the game had a hacker-friendly wibe to it. For instance DEU (the first editor I used) was released in 1994 (https://doom.fandom.com/wiki/Doom_Editing_Utilities). The 'unofficial specs', still invaluable today if you want to hack Doom, were released in 1994: http://www.gamers.org/dhs/helpdocs/dmsp1666.html

Magazines would bundle floppies (and then CDs) full of levels, with new textures and recorded games. Total conversions were made. Tools appeared to directly manipulate the executable and achieve various effects. As far as I remember no other game before had clustered such a large and active community around it? (which is not to say that no other great and amazing games existed before, so many gems lie in the past!)

And then there was the networked play. I spent an afternoon with a friend soldering a cable to play 'null-modem', and we got it working around ~6pm. At 5am the next day we were still playing, me on a luxurious 486 DX2-66, my friend in a tiny window on a 386 DX-33Mhz, both with red eyes. This was an experience like quite no other at the time.

The gameplay was simplistic but huge fun. The immersion was intense. The tech was stellar. But I am obviously biased by nostalgia ;)

dahart3• 6 years ago

I’ll suggest not for story, just for overall surprise. Doom was a big leap over what came before it. Doom 3 wasn’t as surprising, even with more story.

I’d turn it around and instead of shooting the idea down, play the game and suggest what games you think will make the history books and get talked about in a thousand years. Even if it’s just some sort of computer or game history class in college, what games made before today will make it through the sieve of history and why?

I’d humbly suggest that story isn’t a very strong reason for the majority of the best games ever made; games are good for other reasons, including but not limited to visuals and graphics, immersion, interaction, engagement, sound, mood, viral play, pushing boundaries on limited hardware, etc., etc.

spiritplumber• 6 years ago

“Over the centuries, mankind has tried many ways of combating the forces of evil... prayer, fasting, good works and so on. Up until Doom, no one seemed to have thought about the double-barrel shotgun. Eat leaden death, demon...”

― Terry Pratchett

AnIdiotOnTheNet• 6 years ago

I once heard a game critic say that he had never played DOOM. DOOM's impact on the medium is so significant that this statement is roughly equivalent to a film critic saying they never saw Citizen Cane or Star Wars. DOOM set the bar for what games could be in a way that's difficult to appreciate from the perspective of inhabiting the medium it helped define.

Historically story in games has been, as Carmack himself once put it, "like story in a porn movie". It can be good or bad, and that can affect the end product's quality, but it isn't what people show up for.

bananamerica• 6 years ago

Awesome works of art with little to no story:

- The Lovers, painting by Magritte

- Nighthawks, painting by Edward Hopper

- Girl with a Pearl Earring, painting by Johannes Vermeer

- Space Invaders, arcade game by Tomohiro Nishikado

- Pacman, arcade game by Toru Iwatani

- Tetris, PC game by Alexey Pajitnov

- Doom, PC game by John Carmack and John Romero

ummwhat2• 6 years ago

I distinctly recall the "Beowolf" story in my English class consisting of "there was a monster so then our baddest dude went out and killed it to death with a sword". Turns out having a good story isn't all that relevant to historical prestige.

c3534l• 6 years ago

The Iliad was the crowning achievement of a literary society with hundreds of years of tradition. Doom was a simple and early innovator. At best, it will be remembered in the way that some fairy tales are: the beginning of a trope, or right of passage. Even that I'm doubtful of. I suspect it will be remembered like checkers and and the game of Ur: historical curiosities of early games. But not a cultural achievement. I'm not sure what it says about us that we think Doom has the same level of literary merit as the Iliad. It's a fun game, but it has neither the depth of chess or go, nor the narrative achievement of even a sitcom or cheap dimestore novel.

beachy• 6 years ago

I vividly remember when Doom swamped the large Oracle facility where I worked. For literally 3 days productivity nose dived as it seemed the entire company was playing this game which had graphics that seemed absolutely impossible on the hardware of the day. To write Doom of as being akin to a "cheap dimestore novel" feels a little like some elitist attitude where creativity doesn't count unless it's in crusty old print.

dahart3• 6 years ago

Nobody claimed Doom has the same literary merit as the Iliad; but it’s a fact that it has a lot of cultural merit.

The Wright brothers built an airplane that was a simple and early innovation, yet will always be remembered. Henry Ford build a simple and early car that will always be remembered. There’s evidence that simple and early innovations are lasting and culturally important.

Who knows if it’ll be remembered in a millennium? No one here, and maybe it will or maybe it won’t, but it already stands above most computer games ever made as an important milestone, it’s place in video game history is pretty solid. No reason to doubt a legacy is possible.

ArnoVW• 6 years ago

More likely it will be remembered like "L'Arrivée d'un train en gare de La Ciotat"

In other words, only by intellectual gaming buffs.

https://en.m.wikipedia.org/wiki/L%27Arriv%C3%A9e_d%27un_trai...

sosodev• 6 years ago

Interestingly the AI remastered version of that video has quite a few views. https://youtu.be/3RYNThid23g

Might an AI capable of remastering DOS games have a similar affect?

phendrenad2• 6 years ago

I think you're onto something, but I think Doom is closer to a Mona Lisa than a Illiad. It's a work of art that has proven it's ability to attract people to it.

Not sure what the Illiad of games is. Maybe there isn't one. Maybe Doomguy and Mario are closer to mythos like Hercules and other demigods.

anthk6• 6 years ago

So, like the old 'Brick Game' ensembling a Tetris machine.

BTW, on portability, the Z-Machine has been ported even to "intelligent" pens. There is even a GameBoy, Amiga, Atari and C64 port.

Sorry Doom lovers, but your knowledge on portability is really low. The Z-Machine and the zillion of Infocom games/ homebrew can be run nearly everywhere. No display? Hook up a printer/serial device.

Have a wifi/internet client? Write a dumb gopher client, set up a dumb server on a VPS/Rpi. You could set a Z-machine playing bot to even be able to play it via IRC.

Also, with a custom dfrotz and a FIFO file you may be able even play it over morse with some software which decodes the morse input from radio and sends the commands to the interpreter, sending the game output back.

Koshkin• 6 years ago

This feels like a breath of fresh air: too many FPGA applications today resort to implementing a simple CPUs (a.k.a. PSM - “programmable state machine”), and the required logic is implemented in its “machine code.”

monocasa5• 6 years ago

I think you'd be surprised how many classic hardware designs take that approach as well. There's nothing wrong with that approach.

AnotherGoodName• 6 years ago

There's an old saying when judging a new architecture. Can it run Doom?

This question arises since pretty much anything can these days. https://www.vice.com/en_us/article/qkjv9x/a-catalogue-of-all...

Now we have a new answer: IT CAN ONLY RUN DOOM

MaxBarraclough• 6 years ago

There is no instruction counter, only DOOM!

floppy1235• 6 years ago

IT IS DOOM

dorgo• 6 years ago

Is it doom complete?

m463• 6 years ago

for $39.95

willis936• 6 years ago

If only mankind was capable of making a machine that can run crysis.

ummwhat2• 6 years ago

That's why we are developing quantum computers.

k__• 6 years ago

How much more efficient is this than running it in software?

I'm asking, because if this thing can render magnitudes bigger/more detailed worlds than a PC and it's basically copy protected because it's "in hardware" this should be the wet dream of the industry.

floppy1235• 6 years ago

Much more efficient (some 0.x watts) and faster - but not very easy to develop and even harder to deploy :)

and you will get in trouble with the amount of code(needed gates) for porting nowerdays doom

floppy1235• 6 years ago

No it will not outperform your GPU for rendering, that is already a specialized hardware

Chirono• 6 years ago

Further down the author says it runs at 60fps, without much headroom. So quite some way behind modern GPUs - the latest doom game can run at 200+ FPS and is vastly more complicated.

That, combined with the cost of the hardware in comparison to a digital copy makes me think this is unlikely to be particularly useful to the games industry. It's incredibly impressive though!

sylefeb6• 6 years ago

(Author here) Thanks - and I agree. That being said this is running 100 MHz on (what I believe is) a relatively low end FPGA? Also my implementation remains simplistic, many things to optimize. But this is a very good and deep question: how can we compare these things? What is the right metric? (FLOPS per watt? err, no, no floating point involved ;) ). I am wondering and this seems quite a difficult/subtle question.

I love GPUs, I spent many year working with them (still do!) and these are beautiful pieces of hardware and engineering (as modern CPUs are). They have evolved beyond our craziest dreams since the NVidia register combiners (https://www.khronos.org/registry/OpenGL/extensions/NV/NV_reg...). The performance we get nowadays is absolutely mind-boggling (I often think we don't fully realize how powerful they actually are).

Can we dream of some sort of mixed platform, where we could 'burn-in' very specific functions into FPGA type hardware that would seamlessly interact with our modern GPUs/CPUs? Is it already happening?

monocasa5• 6 years ago

That's way more expensive than the margins they're used to for distribution.

And the xbone not getting hacked in it's lifetime proved that they can have their cake and eat it too.

vmception• 6 years ago

even with OpenCL I find FPGA's extremely complicated to program on

it doesn't help that Intel is charging $5,000 licenses to compile on them, for some things

causality0• 6 years ago

Until it takes control input it's more of an electronic sculpture resembling Doom.

sylefeb6• 6 years ago

True - I only (partially) re-implemented the render loop, and this is far from the complete game. A game is always much more that its core technical components.

Adding a keyboard/joystick input is high on my todo. In terms of moving around this really should be just a question of wiring it to the board: the renderer takes a generic x,y,z + angle viewpoint as did the original engine. However, this also means checking for collisions with the BSP scene which is fun to implement (a nice trick in a BSP is to shift the line equations and check with a point as opposed to checking with a disc of some radius).

Side note: I instrumented chocolate-doom (fantastic port) to output the path shown in the video. Initially I was loading a demo lump, but I realized that these are only the inputs and could not easily reproduce the exact way the game answers them (for example, progressive acceleration and of course collisions).

Next up on my list are correct blinking lights, working doors/lifts and sprites (things + enemies). But I also want to optimize it, and to release the language I used to make this. So quite a huge todo; we'll see how it goes. In any case all of that will be made available so everyone can join the fun!

mng22• 6 years ago

Great stuff, cool project. Could you share a few thoughts on your language and transpilation approach?

The DooM-chip: no CPU, no opcodes, no instruction counter

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