[Coco] Virtual disk file formats

[Bill Pierce]

Dave is mostly right. There is no format on VHDs... just a pc file containg raw sector by sector data in order.
The dsk files are much the same with the exception JVC format dsks "can" have a header describing the disk size, but most people don't use it (it's optional). I think Mess and VCC ignore this (though Vcc dsks created with Vcc have a 2 byte header), but XRoar seems to like the 2 byte header, can't remember at the moment. The other exception is DMK disks which contain an "exact" image of a disk including the in between track timing marks and info. This was the native format for David Keil's Coco emulators. XRoar used this as well, but I think they slacked up on that and now allow writing to JVC disks as it used to just read them only.

For the most part, you're safe with straight sector vhds & dsks.

Blank disk images can be created with Vcc by mounting a dsk with a non-existing name including the ".dsk" extension. You will get a dialog with a choice of JVC, DMK, & VDK. Use JVC and set the sides and size to what you need. These disks can be used in all Coco emulators and DriveWire. It does not create VHDs in this manner, but I think we're going to add that feature in a future revision.

The other alternative is the ToolShed utilities. The DECB utility will create a DSK or VHD of any size/type you want. To create a VHD just specify VHD as the filename extension. Basically, it follows JVC's "no header" format.

 

 


Bill Pierce
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-----Original Message-----
From: Dave Philipsen <dave at davebiz.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Thu, Feb 18, 2016 4:08 am
Subject: Re: [Coco] Virtual disk file formats

I'm pretty sure (but I could be wrong!) that there is no format per se for these types of files.  I think they are merely straight sequential dumps of the sectors of a drive.  So, really, the format is determined by the computer or operating system.  In other words, if I had a DECB disk and I dumped the contents of each sector of that disk starting with sector zero to a file, then I would have a disk image.  The same would hold true for OS9 or any other disk format or any other type of disk whether floppy, hard disk, thumb drive, sd card, etc.DaveOn 2/17/2016 11:30 PM, Salvador Garcia wrote:> I have been reading about DSK and VHD files that correspond to virtual disks that are compatible with VCC and Drivewire (among other systems). Where can I go to learn more about their formats and how they can be created? Thanks, Salvador>>>-- Coco mailing listCoco at maltedmedia.comhttps://pairlist5.pair.net/mailman/listinfo/coco