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SNES (Playstation) finally plays CD-ROM games
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Author:  Kismet [ Fri May 05, 2017 9:15 am ]
Post subject:  SNES (Playstation) finally plays CD-ROM games

Hey guys,

I thought you might want to know that Ben Heck actually got the thing to work, with the first game working from the CD-ROM being magic floor.

https://www.youtube.com/watch?v=gaIfPuziJ-0

Author:  MottZilla [ Fri May 05, 2017 11:15 am ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

Well that's good to see. Now will someone make a functionally equivalent clone? And hopefully the same sort of fix for Magic Floor will fix Super Boss Gaiden.

Author:  tepples [ Fri May 05, 2017 11:25 am ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

MottZilla wrote:
Well that's good to see. Now will someone make a functionally equivalent clone?

How much of a BIOS will it need? Nintendo and/or Sony still technically owns that.

Author:  Señor Ventura [ Fri May 05, 2017 12:45 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

Is that the 32 bits snes cd?.

Author:  tepples [ Fri May 05, 2017 12:49 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

It's the 16-bit version of the Super NES CD. I think the 32-bit version just became the PS-X after Sony cut out the dependency on a Super NES host.

Author:  Señor Ventura [ Fri May 05, 2017 4:30 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

tepples wrote:
It's the 16-bit version of the Super NES CD. I think the 32-bit version just became the PS-X after Sony cut out the dependency on a Super NES host.


The 16 version is only a snes with CD, and nothing more, right?.

Author:  Espozo [ Fri May 05, 2017 6:00 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

Correct. There's not much more they could have done, as there's really no way to enhance the video hardware. I think it's unfortunate the PPUs in these systems didn't have additional busses going to either the cartridge or the expansion port, (reading from either both this and vram, or just this) but that would have cost more money. The PPUs actually take 16 bits per pixel for BGs from vram, which could have been used for a straight up 16bpp bitmap mode had the SNES been given 128KB of vram as originally intended or if what I said earlier was true, which would be more important because the transfer rate to vram is so slow.

There's no advantage the SNES PlayStation has over a standard SNES with the MSU-1. In fact, it's even worse, as CD access times are slower and there is only a 256KB buffer for CD data.

Author:  93143 [ Fri May 05, 2017 8:03 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

Espozo wrote:
There's not much more they could have done

Attachment:
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egm-snes-cd-1992-article.jpg [ 161.81 KiB | Viewed 1697 times ]

Author:  MottZilla [ Fri May 05, 2017 9:20 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

tepples wrote:
MottZilla wrote:
Well that's good to see. Now will someone make a functionally equivalent clone?

How much of a BIOS will it need? Nintendo and/or Sony still technically owns that.


You could possibly implement your own compatible freeware BIOS. Especially since a whole two games currently exist and they probably don't depend heavily on the BIOS doing much more than loading some data into memory.

It's very unlikely anything will ever happen with it. But it's somewhat interesting to see. As Espozo said the MSU-1 is potentially more interesting for adding the features of massive storage and CD quality audio. But it's a different beast than the CD-ROM system.

You could make something using the MSU-1 that is more like the CD-ROM system idea if you implemented the MSU-1 on a stand alone cartridge that had a BIOS and some RAM to load game contents into from the SD memory card or whatever storage you were using.

Author:  Myask [ Fri May 05, 2017 9:51 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

Quote:
In addition to this change, Nintendo will build in a software security device that will make illegal duplication of the software impossible.
:lol: :roll:

Author:  Espozo [ Fri May 05, 2017 10:27 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

@93143 And games using this CD add on would still be bottlenecked by shitty object vram management and tile uploading engines. Unless you're dealing with 3D rendering, I think there comes a point where increased CPU power won't improve the appearance of the game at all (a 20MHz 32bit ARM processor isn't going to make Donkey Kong Country look any better). However, I think there still could be one way to improve the graphics if you have extra CPU power, which would be to devote the main CPU to mid scanline raster effects. I think I heard you can't change the Mode 7 parameters mid scanline, but I'd imagine you could change the BG mode and turn the right side of the screen into a coprocessor rendered buffer for a 4 player racing game? How about for really large objects, have the middle be a BG and the edges sprites, so you don't use up an entire BG or heavily reduce the amount of sprites per scanline?

Author:  Oziphantom [ Fri May 05, 2017 11:49 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

The SNES already has top of the line looking games, Star Ocean for example, using the extra power for more graphics fidelity is a moot point. Using it to improve physics and AI would be handy though. Also using it to do on the fly decode of graphics so you can do smaller loads from the Disc and pack more into RAM would probably be useful.

The other thing is the C lamers can probably just code in C on the new chip and avoid having to do ASM. :P

I also think if we can get the CD-ROM system working with say more RAM, that it would be a lot cheaper and easier to sell and market new games on CDs rather than expensive repro carts, or repro carts with expensive custom chips like CICs and MSUs

Author:  Kismet [ Sat May 06, 2017 4:11 am ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

The "right" thing to do with todays technology would be to build a FPGA SNES.

Then there are two possibilities:

1) Utilize the MSU-1 as something purpose-built for the FPGA SNES, development can be done in emulators or with the SD2SNES on other real hardware.

2) Utilize a SNES-CDROM mode that is booted when the cartridge slot is not populated using a re-engineered bios.

So basically the FPGA boot sequence would be "check for cart, check for cd-rom image, check for msu-1 image" and load the FPGA core that works with those modes. Nobody really wants to bother with burning physical discs, and since there are no actual physical SNES CD games to worry about compatibility with, connect that to a micro-SD slot that just emulates a cd-rom with redbook audio passed through digitally. The MSU-1 core would likewise utilize a fully digital path.

Just based on what was seen of the SNES-CDROM Playstation it's pretty clear that the unit they had was meant to be something of the same idea of the PC Engine Duo. Just based on how the hardware was laid out, the CD-ROM unit was just connected to the expansion bus on the PCB itself, and the chips on the PCB would correspond with chips you find on the physical cd-rom on a PC version of the drive. Thus it was likely that an "addon" version would have been produced as well.

Author:  byuu [ Sat May 06, 2017 8:18 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

Espozo wrote:
There's no advantage the SNES PlayStation has over a standard SNES with the MSU-1. In fact, it's even worse, as CD access times are slower and there is only a 256KB buffer for CD data.


128KB. They reused SNES console WRAM chips, 2x64KB, inside the BIOS cartridge.

Yes, you can use the system work RAM, but then you'll have less RAM for your actual game than a stock SNES.

Quote:
You could possibly implement your own compatible freeware BIOS.


Yeah, it's essentially a really clunky interface to load data off CDs in very small chunks at 1X CD-ROM speeds.

The MSU1 can do 4GB instead of 700MB, at the full 2.68MB/s DMA bandwidth instead of 150KB/s, and no seek times, and you can read data and play Redbook audio at the same time, and the interface is many times simpler, and implementing it elsewhere (sd2snes, Snes9X, etc) is a lot simpler.

You can impose artificial limitations like waiting a full second for every 128KB you read from it, and not mixing data reads+audio playback, if you want the authentic "this would work on the SNES PlayStation" experience.

Quote:
Unless you're dealing with 3D rendering, I think there comes a point where increased CPU power won't improve the appearance of the game at all


Eventually you would switch from using the SNES PPU directly to using it like the MSU1 uses FMV, and you'd be capped at 240x144x256 colors@30fps. Given Breath of the Wild runs at 30fps, that's ... not really all that horrible a limitation. But it really begs the question of, "why?!", to the point that even "because I can" sounds incredulous.

Quote:
or repro carts with expensive custom chips like CICs and MSUs


Everyone will instead have to buy far more expensive CD-ROM drives for their SNES expansion ports.

We can't even get adapters made for it unless we buy a minimum of 5000, plus a setup fee of $5,000+.

Quote:
The "right" thing to do with todays technology would be to build a FPGA SNES.


Why? Every person who's tried won't release their source.

And even if they did, how many people have FPGA boards and the knowledge to flash FPGA code onto them?

Author:  MottZilla [ Sat May 06, 2017 10:03 pm ]
Post subject:  Re: SNES (Playstation) finally plays CD-ROM games

byuu wrote:
Quote:
You could possibly implement your own compatible freeware BIOS.


Yeah, it's essentially a really clunky interface to load data off CDs in very small chunks at 1X CD-ROM speeds.

The MSU1 can do 4GB instead of 700MB, at the full 2.68MB/s DMA bandwidth instead of 150KB/s, and no seek times, and you can read data and play Redbook audio at the same time, and the interface is many times simpler, and implementing it elsewhere (sd2snes, Snes9X, etc) is a lot simpler.

You can impose artificial limitations like waiting a full second for every 128KB you read from it, and not mixing data reads+audio playback, if you want the authentic "this would work on the SNES PlayStation" experience.


This would be the most practical way to make CD-like games for SNES today. Make a cartridge that just implements the MSU-1 setup with a small bootstrap or BIOS and a healthy amount of RAM. If it could be produced at low cost it might actually go somewhere. But it would be relying on homebrew creations entirely unlike the SD2SNES and MSU-1 which are interesting to people since it's all hacks to add things to existing games. It's too bad the MSU-1 was never realized as a add-on. Would it be possible or feasible to make a MSU-1 Game Genie style cartridge? So that you could just sell the MSU-1 functionality that could be used with any cartridge. I know unlike the 21fx the MSU-1 lives on the A-Bus so it would have to be a cartridge. Actually the idea of combining a Game Genie concept and MSU-1 together would be really cool to use an original cartridge with patches to play CD quality audio.

But back to the ideas of making any CD-like SNES system today I think the MSU-1 as a standalone cartridge with bootstrap and some amount of RAM would be the most viable. Far more so than any CD-ROM idea since the MSU-1 could just be a cartridge. I don't know how expensive of a FPGA or other circuitry you'd need to implement the MSU-1 but if it could be made for a reasonably low cost then maybe people might be interested.

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