[Coco] How to create an 80 track 2 sided disk with SDC

Barry Nelson barry.nelson at amobiledevice.com
Thu Dec 17 21:29:53 EST 2015

SDC-DOS may not access a double sided disk, or access more than 80 tracks, but ADOS will, or RSDOS with the proper patches. So you could load ADOS (or ADOS3 if this is for a CoCo 3) into one of the other flash banks on the CoCo SDC, say bank 3 for instance, then after you mount the disks in SDC-DOS, switch to ADOS like this…

RUN @3

Even ADOS will not access all of a 80 track double sided disk at one time, but it will access 80 tracks on one side, and assign the second side to another drive number. Since the SDC emulates the CoCo floppy controller including the side select line since it needs that for OS9, I think this should work. You could get 4 virtual disks of 80 tracks mounted this way by using SDC disks 0 and 1. Be care to never write to these disks under SDC-DOS or RSDOS or else, poof goes your data.

> Darren A mechacoco at gmail.com 
> Wed Dec 16 18:52:10 EST 2015
> On Wed, Dec 16, 2015 at 2:30 PM, Nick Marentes wrote:
> > Up until now I have been using the standard default DSK format with my
> > CoCoSDC (40 track single sided).
> >
> > How can I create an 80 track double sided DSK file on the SDC?
> >
> > I know about using the DRIVE 0,"NEWDISK",NEW command but how do I speciofy
> > an 80 track double sided drive?
> >
> > Nick
> SDC-DOS will not access the 2nd side of a double-sided DSK image. The trick
> used in DECB for floppy disks (patching the drive selects table) will not
> work.
> If you just want to create an 80 track, double-sided image for use with
> OS-9, you can try the following commands:
> DRIVE 1, 4
> DSKO$ 1,19,18,"",""
> All this does is enlarge the size of the DSK file to hold 2880 sectors (2
> sides * 80 tracks * 18 sectors-per-track).
> - Darren

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