nesdev.org

The CD7 is a CD-ROM drive that can be connected to the Game Doctor SF7 SNES backup device, so that ROMs can be loaded off of CDs in addition to floppies. The Dumper reversed engineered the circuit for interfacing a MKE CD-ROM drive with the SF7, so that people could make custom clones of the drive.

Using The Dumper's schematics and my own custom layout based on measurements taken from multiple different external CD-ROM drive enclosures, I had custom printed circuit boards made so that a professional clone of the CD7 could be built.

I plan on making a prototype clone based on these custom circuit boards, and if I can get everything to work, I will make at least 3 more drives and sell them on Ebay, with a starting price of the cost of parts... which I actually don't know precisely yet, as I still haven't ordered the ICs.

Below are pictures of the circuit boards, which have 4 custom boards shown alongside a non-SF7 compatible parport-IDE interface. I have included this other interface because it resembles what the final CD7 interface circuit board will look like, i.e., two parports on the back and one MKE ribbon cable pin set on the front side.


Front (MKE side)



Back (parport side)

Who said that the SNES never had a CDROM drive made for it

Heh for a second I thought you had the ASIC board made to replace the trivial octal tristate :)

What is the male connector for? Just in case someone doesn't have a male-male cable?

kyuusaku wrote:Heh for a second I thought you had the ASIC board made to replace the trivial octal tristate

What is the male connector for? Just in case someone doesn't have a male-male cable?

That other PCB is from one of my enclosures, and it has nothing to do with the CD7 clone other than the fact that I "borrowed" its layout. Most of the parallel port enclosures use a similar layout for their interface boards, which is why I based the layout on that layout: there are multiple retailers that sell enclosures that will fit this CD7 clone interface and both parport and SCSI enclosures that often sell on Ebay should also work with this CD7 clone interface.

I am not sure what the PCB in the center uses its male parport for, but it is on my layout so that it can fasten to the enclosure. If I didn't include solder holes for it, then it wouldn't adequately fasten onto the enclosure, and since I will be desoldering parts from the old interfaces, it won't be any additional cost. So on the CD7 clone, that male interface won't serve any purpose other than matching the form factor of the enclosures' original interface.

The Whole GD7 to IDE project died with the CR forums right?

I would really like to see something newer than a 10+ year old MKE drive interfaced to the CD7. Old CDROMs are anything but reliable.

Unless you have a source of never-been-used MKEs?

If you want an MKE<->IDE interface, you'll have to do it yourself. The GameStations with IDE drives do not convert MKE to IDE as previously thought; they have new IDE registers and patched the GD ROM to use that instead.

kyuusaku wrote:If you want an MKE<->IDE interface, you'll have to do it yourself. The GameStations with IDE drives do not convert MKE to IDE as previously thought; they have new IDE registers and patched the GD ROM to use that instead.

Are you saying that it is possible to wire an IDE interface to the SF7's parport, and then use the GameStation's BIOS? Has anybody successfully done something like this?

I haven't touched my CD7 cloned circuit boards since I made this thread. New job and all is keeping me from working on any side projects. Maybe next weekend... yeah, or maybe the weekend after that, I will finally get around to it...

It's not possible without using a microcontroller and latches to translate MKE to IDE. MKE is proprietary and to my knowledge barely documented online, IMO it's not really worth reverse engineering now.

Actually I've recently(ish) discovered that the IDE protocol is actually quite simple...

Instead of a CDROM, perhaps we should think about a GD7 Parrallel to IDE-CF adaptor. (plus a new BIOS, either patched in via the save-state-exploit or a whole EEPROM replacement)

I'm abit rusty on the parallel port, is it Bi Directional 8-bit or is it that 4-bits status in plus 8-bits data out? What does the GD7 support?

I finally got around to putting together my first CD7 clone. Pictures of the populated circuit board is below. Note that there is an extra dummy parport, so that the circuit board can fasten strongly to the back inside of most external drive enclosures.


MKE side


parport side

However, I am having a problem. When I power on my SF7, it says "(Load CD Games) For 562B Drive" in the upper right corner and "Insert CD Please" in the middle of the screen. Once I place a CD in the drive, it says "Waiting..." in the middle of the screen and I can hear the CD drive spinning. After roughly 5 seconds of this, the spinning stops and the middle of the screen changes to say "Disk Format Error !".

So what am I doing wrong? I made a small ISO9660 image and burnt it to a blue CDR at 1X speed. Here is the command that I used to make the image: I used the file naming scheme described here.

1. Could this be a sign of a problem with the circuit board that I made?
2. Could this be caused by the kind of CDR that I am using?
3. Is there any practical way for me to obtain a known working ISO or even better, a CD?

I have enough parts to build three more clones, but I won't do that until I can get my first clone working.

Jagasian wrote: 1. Could this be a sign of a problem with the circuit board that I made?
2. Could this be caused by the kind of CDR that I am using?
3. Is there any practical way for me to obtain a known working ISO or even better, a CD?

I have enough parts to build three more clones, but I won't do that until I can get my first clone working.

I suspect that the interface is working OK. What may not be OK is the drive- either it's bad, it does not like CDRs (did you use a CDR or CDRW?), or the image is bad.

If the interface wasn't working right, I suspect it would've failed to work at all. It sounds like it got pretty far- asked for a disk, accepted disk, spun it up, then read from it. That most likely means the interface works.

Any particular reason you're burning at 1X? I'd say to burn at maximum speed on the cheapest CD-R available, just because that would be what the burner is designed towards.

But if these old drives can't read any CD-Rs, that would suck.
I don't think they're as reflective as pressed CDs, and CD-RWs even less so.

If it's any help, I have an old CD-ROM + soundcard interface stashed away somewhere (I'm guessing it's MKE) that I could do some kind of test with. I'm kinda out of CD-Rs at the moment, though I could probably scrounge one up. I already have an old PC set up anyways.

It can certainly take CD-Rs, but probably not CD-RWs.

IIRC discs need to be Mode 1, ISO9660 only (no Joliet), 8.3 filenames (level 1), no directories. I'm not sure about the character set, you're using DOS right? I don't believe multisession settings matter.

It looks to me like your image should work... try ISO9660 charset though.

kyuusaku wrote:It can certainly take CD-Rs, but probably not CD-RWs.

IIRC discs need to be Mode 1, ISO9660 only (no Joliet), 8.3 filenames (level 1), no directories. I'm not sure about the character set, you're using DOS right? I don't believe multisession settings matter.

It looks to me like your image should work... try ISO9660 charset though.

I am not familiar with Windows. Can somebody recommend a good free CD burning program that actually lets you select the details of the ISO format? I used my wife's laptop to burn an ISO made on my Linux computer using mkisofs. I was surprised to find that the CD burning software that comes with Windows does not allow for specifying the burn format. Maybe if I just used some good software to do the burn, I wouldn't have these damn format problems.

http://www.burnatonce.com/
http://www.deepburner.com/

http://www.nero.com/ -- OLD version if you can find one

Personnaly I reccomend Nero, it does give you a fairly good set of options.

There is even a Linux version (!).

For windows apps I recommend Cdrwin by Golden Hawk Technology or ImgBurn by Lightning UK. CDmage can help you examine images and ISOBuster can help you examine a CD without making an image if you need to test the disc type.

When I last used my GDSF CDROM, I'm pretty sure I used Nero to create and burn the disc.