Subject: Re: What do you think?
To: None <David@ixibbs.iximd.com>
From: Marcus Comstedt <marcus@idonex.se>
List: port-dreamcast
Date: 04/30/2001 18:03:21
>>>>> "David" == David  <David@ixibbs.iximd.com> writes:

  David> If you look at this schematic:
  David> http://members.nbci.com/_bitmaster_/dc/dc-ide.pdf
  David> You will see that the only thing he has hooked up to the DC-Port is an
  David> IDE port,

If you look at it yourself, you'll see that there is a bunch of buffer
circuits and gates as well.


  David> which means that IDE is in there if you want to try an atapi
  David> based device.

AFAICT, it only means that you can build a primitive IDE interface
with a few buffers and gates.  IDE isn't really rocket science.


  David> The problem that I see is that Harddrives need a bios of somesort to
  David> actually run (unless I'm wrong).  Atapi drives like CD-ROM's and ZIP
  David> drives don't need a BIOS on the controller.

Uh?  Any device will need a driver (generic or specific) of some sort
to talk to it, or it will not do anything.


  David> Can someone tell me how you have the GD-ROM driver working?  I mean is
  David> there a way to find out if it is SCSI or IDE? (It has to be one or the
  David> other doesn't it)

The interface is IDE-like, but the actual commands are not standard
SCSI/ATAPI commands.  (Before you ask:  The GD-ROM is not connected to
the same bus as the expansion port.  If you take a look at
http://www.segatech.com/technical/dcblock/index.html you'll see the G2
bus as labeled "16b x 25M", and connected to the sound subsystem and
the white "IF" box which is the expansion port.  The GD interface has
it's own connection to the System ASIC, as indicated by the unlabeled
arrow.)


  David> At this site he also has a Pin-Out of a SoCalled CD-ROM port:
  David> members.nbci.com/_bitmaster_/dc-index.htm

  David> Would this be the actual port that the GD-ROM is hooked to?

Probably, although the address listed isn't the one you use to access
the GD-ROM.


  // Marcus