Digital Foundry Retro - The Making of Doom on Super NES ft Randy Linden

[laymanpigeon]

 

[Tanooki]

Oooooh nice, someone actually approached making a video docu-history thing about this, and thankfully DF Retro.  I can't think of but maybe one or two others I'd trust with that kind of piece, and even then, I don't think they'd get more technical but heavier on the history and process than the figures.  THANKS>

[Kirk_Johnston]

Cool. Def gonna give that a watch. Still waiting on some genius coder doing a modern version of this on SNES that really pushes everything to the limits in terms of what the system is capable of.

[CapitanClassic]

Randy Linden did mention in the video that someone identified a technique after he put his SNES source code on GitHub that could increase performance. Something regarding using DMA to double the pixels (the 2x pixels is the low res mode that was originally designed to run Doom on a 386, but is also used on the SNES) rather than performing the doubling of the pixels using the SuperFX2 chip.

 

I believe he said instead of getting the 10fps-15fps that the game normally runs at, he expected the game to run at 20fps-25fps.

Edited September 13, 2022 by CapitanClassic

[Tanooki]

@CapitanClassic Yes that's exactly what he said.  The doubling technique taken off software in the FX package of code, let HDMA handle it for pixel doubling, and the increase was found to double the existing values and should center largely around 25FPS, which for PAL would be full potential (30 for NTSC not stuck on icky PAL.)

 

I'd love to see someone take that tweak, code it in, and compile a speed corrected version of the game.  I've got my original cart, but I'd love to side by side the difference.  Seems far cleaner than that sloppy as sin overclocking the FX itself that was done some years ago.  It showed real improvement through a work around in hardware, but to get this from a recompile would be fantastic.

[Punisher5.0]

Fantastic video. Randy is a legend and I hope someone can follow in his footsteps and implement the pixel doubling on the SNES side. It was really interesting hearing him talk about the reasons for no ceiling or floor textures. It might be possible to implement them with a more powerful fpga version of the FX2.

[Kirk_Johnston]

Randy also mentioned something that made it sound like it would also be possible to add the ceiling and floor textures in there too, with a bit of optimisation I think, so I'd love to see that in there as well.

 

Honestly, I think the SNES has a lot more to give when it comes to a fully-optimised version of DOOM on the system.

[Tanooki]

Most definitely I think Punisher there is right.  Even Randy mentioned FPGA about the FX.  It was all about the utter limitation of the hardware why you didn't have the missing textures above and below, ran out of cpu cycles.  So if you did a FPGA that say doubled or tripled those cycles, it should allow the amount needed to pull that off, if not the rest of the missing content to a point.  Mind you, that would require some ROM hacking/expansion, making another fake chip of sorts like the SD2SNES(MSU) kind of does, one that can go over the 2MB storage limit of the FX2 capabilities.  Maybe a faux FX3 chip, have it run at 30 or 40mhz, adding more ram, more cycles, and removing the 2MB cap, say upping it to 4 or 6 perhaps (Phantasia on SFC is a 6MB cart due to all that recorded singing and other samples.)

 

That would be a really fascinating project, hell if I could code in the slightest, I'd go for it out of sheer curiosity.  I mean, if some DOOM nut wants to run the game on a damned digital pregnancy test, why not make the SNES game as close to the original as imaginably possible going outside the box of the little red cart?  That would be a real badge of honor.  Full DOOM if not Ultimate Doom on SNES with a made up FX3 chip.

[CapitanClassic]

Regarding a SuperFX3 chip: at some point you are just running Doom on a Raspberry Pi, and writing a VGA to SNES video driver. Interesting as a novelty, but lacks the substance of a game that is actually rewritten to the hardwares native assembly.

 

[Punisher5.0]

3 hours ago, Tanooki said:

Most definitely I think Punisher there is right.  Even Randy mentioned FPGA about the FX.  It was all about the utter limitation of the hardware why you didn't have the missing textures above and below, ran out of cpu cycles.  So if you did a FPGA that say doubled or tripled those cycles, it should allow the amount needed to pull that off, if not the rest of the missing content to a point.  Mind you, that would require some ROM hacking/expansion, making another fake chip of sorts like the SD2SNES(MSU) kind of does, one that can go over the 2MB storage limit of the FX2 capabilities.  Maybe a faux FX3 chip, have it run at 30 or 40mhz, adding more ram, more cycles, and removing the 2MB cap, say upping it to 4 or 6 perhaps (Phantasia on SFC is a 6MB cart due to all that recorded singing and other samples.)

 

That would be a really fascinating project, hell if I could code in the slightest, I'd go for it out of sheer curiosity.  I mean, if some DOOM nut wants to run the game on a damned digital pregnancy test, why not make the SNES game as close to the original as imaginably possible going outside the box of the little red cart?  That would be a real badge of honor.  Full DOOM if not Ultimate Doom on SNES with a made up FX3 chip.

I don't know what frequency it would take to make it happen but we already have an overclock option with SD2SNES. It might be possible to do this with "just" a change to a register for a larger ROM. 

[laymanpigeon]

If he only knew that off-load is possible when he made Doom, it could have been released sooner on older SuperFX and then company he worked for could have went to develop FPS specifically made for SuperFX 2.

 

Less variation in textures and enemies, thus floor ans ceiling textures could be in such game and fewer enemy NPCs, but with sprites for all 8 angles of them.

[Tanooki]

I've got the SD2SNES so I'm aware of the overclocking, easy to find and exploit and specifically has a FX chip setting for it if I remember right.  I think I used it before out of curiosity on Starfox and it got more fluid feeling since the speed was increased, so Doom should exhibit the same.  It's a half baked work around to the pixel doubling that would double the speed of the existing cart too like Randy spoke of.  He seems to think doing just that change to the register to USE vs NOT USE the HDMA would do the trick, so I'd believe it.

[Kirk_Johnston]

On 9/14/2022 at 6:45 PM, CapitanClassic said:

Regarding a SuperFX3 chip: at some point you are just running Doom on a Raspberry Pi, and writing a VGA to SNES video driver. Interesting as a novelty, but lacks the substance of a game that is actually rewritten to the hardwares native assembly.

 

Yeah, for me it only truly counts if it's capable of running on either a stock SNES or a SNES using a cart with one of the official enhancement chips that was available at the time and without any tricks that wouldn't have been possible on the console properly back then.

 

But, I wouldn't complain if some new SNES games came out in modern times that basically did something like this in principle. Look at Paprium on Genesis, which I think adds a few extra bits and bobs into the cartridge that weren't in any Genesis games from back in the day, and that's a legit modern-day Genesis game, so I have no problem with the same thing happening on SNES.

Edited September 15, 2022 by Kirk_Johnston

[Tanooki]

@Kirk_Johnston So basically for SNES that's the MSU-1.  That thing allows for CD audio, streaming video games (a laserdisc arcade game was converted) and a bit more.  It's a real chip, at least as a FPGA option on the SD2SNES, but never actually manufactured to a cart like paprium, but if someone wanted to pay, it could be.

[Kirk_Johnston]

10 hours ago, Tanooki said:

@Kirk_Johnston So basically for SNES that's the MSU-1.  That thing allows for CD audio, streaming video games (a laserdisc arcade game was converted) and a bit more.  It's a real chip, at least as a FPGA option on the SD2SNES, but never actually manufactured to a cart like paprium, but if someone wanted to pay, it could be.

Well, as long as the solution can be put in a cart that would still cost basically regular price, around £50-£60 in modern times, that would be fine, bit it can't be too expensive or it defetad the point imo, because my thinking is it needs to be able to be sold in the thousands to make sense beyond just hackers or whatever. And I'm thinking a bit less niche and more genuinely commercial than that.

[johannesmutlu]

If someone could unfold it’s full potential of the reality engine for snes doom,and add and restore all missing features of it,including better hit & collision detection,better physics,full textures on both floors & ceilings,add back in those missing sound effects etc,,,

i can rest in peace,

but to make that happen we must force the fx2 chip to go beyong it’s 2MB limit,overclock it,add faster ram & rom and do double pixel trough snes hdma instead and we will get a better snes version of it😁

[Tanooki]

Reality Engine is N64 genius.

 

Also the FX/FX2 did hit its full potential on the SNES at the levels of power either version was allowed vs the capabilities on the SNES itself.  You won't be getting better hit/collision detection etc in Doom on SNES, that game quite literally used up almost every single last byte of storage on the 2MBit chip they used...Randy said so, and he's the one who was capable of doing this.

[laymanpigeon]

On 9/18/2022 at 10:37 PM, Tanooki said:

Reality Engine is N64 genius.

 

Also the FX/FX2 did hit its full potential on the SNES at the levels of power either version was allowed vs the capabilities on the SNES itself.  You won't be getting better hit/collision detection etc in Doom on SNES, that game quite literally used up almost every single last byte of storage on the 2MBit chip they used...Randy said so, and he's the one who was capable of doing this.

Randy also wasted bytes on some superflous features such as on trying to implement Super Scope on Doom...

[Tanooki]

Not enough to hit his confused wish list, especially the floor/ceiling which was already explained beyond system capability, not storage.  Maybe some bug fixes, but realistically I'd imagine a basic password system would be more realistic.  It's so packed in there, it didn't even have room for a title screen which is sad.

[laymanpigeon]

19 hours ago, Tanooki said:

Not enough to hit his confused wish list, especially the floor/ceiling which was already explained beyond system capability, not storage.  Maybe some bug fixes, but realistically I'd imagine a basic password system would be more realistic.  It's so packed in there, it didn't even have room for a title screen which is sad.

It would have been better if they instead made spin-off/separate installment of Doom specific to SuperFX like Doom on Nintendo 64 was.

[Tanooki]

Not really, you have to keep in mind the year it came out.  Doom while huge wasn't huge immediately in December 1993 when it arrived, it was a slow roll into a roar well well into 1994 into the game being trumped by Doom 2 later that year which was utterly as much of an expansion pack by definition than a new game given it was a new weapon(super shotgun), new end boss and new stages.  Doom much of 1994 lived and died by the shareware model, retail copies came after the fact and only by mail order in that era, and console ports and conversions were released along side of Doom 2 for PC in Sept/Oct of 1994 (and after.)  The SNES came popped out along side of Doom 2 and PS1 Doom which was a hybrid with some D2 stuff.

 

When the SNES game came out Doom really finally had started to hit its stride.  It would have made little to no sense to release a Doom spinoff(would have just been a sequel at that rate.)  By the time the N64 got it's true Doom 3 game Doom 64, the original finally was in actual stores on CDs along side of Ultimate Doom and Doom 2.  Then it would make sense to do that because even iD had been pandering third party created works under their own publishing with Final Doom, the Master Levels, etc.  Dooms early first few years were confusing and overlapping which was strange.