Any chance of a CDROM2 unit on an FPGA?

[MottZilla]

Did you post in the right thread? I have a feeling you might have intended to reply in a different thread. We were talking about ways to play CD-ROM games without an actual working CD-ROM drive. My suggestion is to tackle it from the BIOS rather than trying to emulate the hardware of the CD-ROM drive. It would work just find if all games follow procedure and use the BIOS to load data from CD-ROM and play Audio Tracks. Rewriting the BIOS functions to instead communicate with another storage device could be achieved. And the software approach would probably be easier and faster than attempting to clone the exact hardware behavior the CD-ROM has.

[Everblue]

So what you are suggesting is that to re-write the bios in a way that ISO games are loaded via the HuCard slot with a device similar in shape to Turbo Everdrive?

How would you go about re-writing the bios on the console?

[Drakon]

The problem i see with de pce cdrom is the red book
audio stuff. How do you gonna control this over the hu slot
or extension port? Since game data/psg sound is very independent
handled to the red book audio.

For proof of concept the nes powerpak reproduces entire audio chips found in famicom cartridges.  The audio chips in the famicom carts only output a standard mono audio signal so if fpga can re-create that then I'm sure you could get something that can re-create red book audio.

[MottZilla]

So what you are suggesting is that to re-write the bios in a way that ISO games are loaded via the HuCard slot with a device similar in shape to Turbo Everdrive?

How would you go about re-writing the bios on the console?

Yes, you just need a device to plug into either the HuCard Slot or Expansion Port to get all the connections you need. The BIOS should contain functions related to all disc operations. You can then hack these routines to use different hardware on this device to get the same data that would be stored on a CD-ROM normally and read by communicating with it. You are basically making the BIOS access a new storage device. It could be done if the BIOS is always used for such functions. The Famicom Disk System on the PowerPAK similarly uses a hacked BIOS I believe.

Again, mixing audio isn't a big deal, you could mix two signals together is inject the redbook audio. The whole task could be done.

[HercTNT]

Did you post in the right thread? I have a feeling you might have intended to reply in a different thread. We were talking about ways to play CD-ROM games without an actual working CD-ROM drive. My suggestion is to tackle it from the BIOS rather than trying to emulate the hardware of the CD-ROM drive. It would work just find if all games follow procedure and use the BIOS to load data from CD-ROM and play Audio Tracks. Rewriting the BIOS functions to instead communicate with another storage device could be achieved. And the software approach would probably be easier and faster than attempting to clone the exact hardware behavior the CD-ROM has.

No Mott, i have no idea what thread i'm in, we were talking about skittles right. I don't have your understanding of the technical aspects, but i do grasp what your trying to do. I was only suggesting that if someone were to use an sdcard to load iso's (that was talked about in this thread right?) yet you would still need a cd capable bios to run said iso as its not emulation right? then using a flash card could cover the bios aspect of the problem. Otherwise i'm an idiot and was just trying to be part of the discussion

[TheOldMan]

Yes, you just need a device to plug into either the HuCard Slot or Expansion Port to get all the connections you need.

It would have to connect to the expansion port. Cards are missing the CD-detect signal
You don't have to re-write the bios, either. You just have to make the device -respond- like the NEC cd adapter.

Seriously: Make an IDE adapter for the expansion port. Then you can adapt whatever card you want to an IDE bus.

[Drakon]

If people can custom make pcbs with connectors for a hucard slot I'm sure you can make a custom connector for the pc engine expansion port.

[HercTNT]

If you read my post on the previous page you will see i already have. its not perfect but it works.

[Drakon]

If you read my post on the previous page you will see i already have. its not perfect but it works.

Oh hey there we go proof of concept yet again.

[MottZilla]

Did you post in the right thread? I have a feeling you might have intended to reply in a different thread. We were talking about ways to play CD-ROM games without an actual working CD-ROM drive. My suggestion is to tackle it from the BIOS rather than trying to emulate the hardware of the CD-ROM drive. It would work just find if all games follow procedure and use the BIOS to load data from CD-ROM and play Audio Tracks. Rewriting the BIOS functions to instead communicate with another storage device could be achieved. And the software approach would probably be easier and faster than attempting to clone the exact hardware behavior the CD-ROM has.

No Mott, i have no idea what thread i'm in, we were talking about skittles right. I don't have your understanding of the technical aspects, but i do grasp what your trying to do. I was only suggesting that if someone were to use an sdcard to load iso's (that was talked about in this thread right?) yet you would still need a cd capable bios to run said iso as its not emulation right? then using a flash card could cover the bios aspect of the problem. Otherwise i'm an idiot and was just trying to be part of the discussion

When I first read your reply it seemed like a reply to a similar topic elsewhere on this board. I think I was thinking of the thread about adding backup ram to a portable console.

The CD Detect signal isn't necessarily needed if you rewrite the BIOS. That signal may be more important to the actual CD-ROM drive, which if you rewrite the BIOS you can bypass that.

Either way, something could surely be done to emulate the CD-ROM to run ISO style images.

[HercTNT]

its all good, i was being a bit of a wise ass anyhow, i figured you meant nothing by it.

[Drakon]

It's perfectly doable.  The nes powerpak re-creates the entire famicom disk system on fpga connected through the cartridge connector.  The famicom disk system loads data off of cheap disk media which is the same concept as a cd, and also contains custom audio hardware which the fpga recreates.  The mega everdrive is a sega genesis fpga device which can play wav files so there's your redbook audio reproduction.

It's not a matter of "can it be done?" it's more a matter of "will anyone with enough skill ever get around to making this?  And if so when?"

[TheOldMan]

The CD Detect signal isn't necessarily needed if you rewrite the BIOS. That signal may be more important to the actual CD-ROM drive, which if you rewrite the BIOS you can bypass that.

Okay, let's assume CD-Detect isn't needed.
Which bios are you going to re-write?
If 1.0, there go all the later games.
if 2.x, there goes altered beast (and a few others, iirc) and the super cd games.
if 3.x, no altered beast, but most everything else should play.

In any case, you're not going to get -all- the isos to play, unless you want to detect which program it is, and switch bios images. Good luck with that....

(I've never said it -can't- be done, though. It's just more trouble than doing an ide converter.)

[Drakon]

Rewriting the bios might be a mega pain.  Even the fds fpga on the nes powerpak uses the regular fds bios dump.

[spenoza]

Doesn't Magic Engine already use a rewritten 3.0 BIOS?