Could the CDI run Doom?

[FelixTheWolf]

Would it actually be possible to run the full game, even if slightly altered?

[EngineerKappa]

 

Ram Raid here shows that a FPS is possible, but you're better off porting Wolfenstein instead of something more complex like Doom. Even here you can see it cheats by having the top and bottom of the walls mirrored. A similar technique was used by Traveler's Tales for Toy Story on the Genesis.

[Doomkid]

I can't find any table anywhere on the entire internet that compares the specs of the SNES to the CDi and can't be bothered to make one myself, but a ground-up engine with a bunch of cut features such as texture mapping, varying light levels, etc. could possibly be made to run, something similar to SNES Doom but maybe even more basic. This is just the opinion of a total layman, the CDi might have more power than I'm giving credit for. As stated above, Wolf3D would be far more reasonable.

Edited October 7, 2018 by Doomkid

[Denim Destroyer]

So I did some light Googling and this is what I turned up thanks to vidgeogameconsolelibrary.com. I'm not an expert in computer hardware so someone please correct me if I am wrong in my analysis. 

The CDI has a faster CPU than Snes does with a 16/32 bit CPU running at 15.5 MHz compared to a 16-bit CPU running at 3.58 MHz for NTSC. Note that CDI had several different models thus explaining why it can have a 16 bit or 32 bit processor. Another thing to note is that the CDI came with 1MB ram and the SNES came with 128KB of DRAM and 64KB of SRAM. The CDI has the benefit of using CDs so storage space won't be as big of an issue as it would on the Snes. The CDI also could have 32,768 colors on screen while the Snes was limited to 256 which according to my research was one of the reason why the Snes port of Doom lacked texture mapping. Snes Doom also includes the SuperFX2 chip which is another 16-bit processor running 21MHz designed to render 3d graphics that the Snes couldn't run on it's own.

It is my conclusion that the CDI might be able to run Doom however considering that Snes Doom used the SFX-2 chip to run the a limited version of the game, one with out texture mapping or rotating sprites, a CDI version would run poorly due to having an overall slower CPU.

As I said I am by no means an expert in computer hardware and all knowledge I have is rather basic. So someone knowledgeable please correct me if I wrong.

Spoiler

CDI

SNES

 

 

[andrewj]

The GameBoyAdvance has a 16.8 MHz 32-bit CPU and 256kbyte of RAM, and DOOM runs on that, so I reckon the CDi could handle it about as well as the GBA.

Edited October 14, 2018 by andrewj

[therektafire]

Hm what is the CDI's GPU like? I would imagine that SNES and GBA doom use some gpu/ppu/whatever-you-want-to-call-it trickery to make the game run faster. I can't seem to find much of anything about the MCD212 GPU but considering it was designed to go in what is essentially a DVD player with a controller port I wouldn't be surprised if your only option is to software render everything PC style which is an issue since the CPU is even slower than a 386. Also another disadvantage of the CDI compared to SNES and GBA is that it doesn't use cartridges so you would need to load the game into ram to be able to run it which even in the best case scenario where you have the 1MB RAM expansion you will still only have 2MB to work with so you will probably need to make some maps smaller to fit.

[Reisal]

According to the visual specs, there certainly would have to do some hackery to get it to work on the CDi, I'm wondering how much would have to be sacrificed even with the 2MB, and how would it handle with Doom 2?

[crazyflyingdonut]

inb4 Hotel Mario and Zelda memes

[Fuzzball]

I'd wager it would probably turn out something like an FMV game of sorts..

[Maes]

On 10/14/2018 at 10:37 AM, andrewj said:

The GameBoyAdvance has a 16.8 MHz 32-bit CPU and 256kbyte of RAM, and DOOM runs on that, so I reckon the CDi could handle it about as well as the GBA.

 

Only that the GBA uses an ARM CPU that gives out about a MIPS per MHz - the CD-i has the equivalent of a 68000 CPU (similar to the one used by the Commodore Amiga, Atari ST, Sega Genesis etc.) running at 15.5 MHz, and that CPU could barely put out 1 MIPS on average when running at 8 MHz. For reference, the 68000 CPU could be likened to a 386 SX CPU (32-bit internally, but only 16-bit data bus), and PC Doom was pretty much unplayable on that, even on the "fastest" variants (25 MHz). In conclusion: the GBA's CPU is pretty much at least 8 times more powerful than the one in the CD-i, and in a CPU-bound game like Doom, that's pretty much everything.

 

Even assuming that, unlike the Amiga, there was no need for a computationally expensive chunky-to-planar conversion, performance wouldn't be good. Most Amiga FPS game look like crap if ran at base specs (which are pretty similar to the CD-i), and are pretty much unplayable on stock Amigas without a dedicated video card to avoid the vexing planar-to-chunky overhead. Even CD-32 titles that have the Akiko chip for this task look quite meh.

 

 

It's quite unlikely the CD-i would be better equipped in this respect, and it offers no 3D acceleration of its own to help with the graphics.

 

Then, there's the issue of the main RAM -PC Doom requires about 4 MB of addressable space. Console versions ran on considerably less RAM by sacrifiicing sprites, sounds, textures, and simplifying levels, so likely the same approach would be required for the CDi.

 

So yes and no: with enough effort you could run some "Doom-like" game on the CD-i, even keeping the Doom engine largely the same, but not without severely cutting stuff and with abysmal performance.

Edited January 21, 2019 by Maes

[Optimus]

Next console I am wondering if it can run Doom is NEC PC-FX.

Cause I recently got one and trying some jap games right now, but it looks very similar to 3DO in few aspects, maybe comparable or slightly faster CPU performance (according to wikipedia 32-Bit NEC V810 RISC running at 21.5 MHz, 15.5 MIPS) it has CD-ROM, 3 MB of Ram (2 MB RAM and 1MB shared, exactly like 3DO) but the hardware is just 2D so it might or might not be useful for Doom (unless the hardware supports sprite scaling and could somehow using it for wall column stretching, but I don't know yet). In worst case one could port Doom from 3DO and replace the hardware stretching with software rendering as a first step and have a very slow port (maybe like slow 386?).

It was playing in my mind as a silly idea (to try and port code from 3DO Doom, but it would be too much work for me now and I rather concentrate on Doom 3DO), and then I wondered which are the last consoles from that era that haven't ported Doom (similar to the site "It runs Doom", I laughed thinking of a fictitious site "It doesn't run Doom YET".