[Coco] Another Coco Virtual Disk Util

Walt Zydhek walt at wzydhek.com
Fri Oct 18 10:52:27 EDT 2013


The biggest issue in using existing VHD images is the fact that the only way
to determine the PHYSICAL parameters of the VHD is to determine if the
drive's first partition is OS9, and get the drive parameters from its LSN0.
Otherwise, assume it is RSDOS formatted with 1 Head, 35 Tracks, 18 Sectors
and divide the VHD file length by 0x27600 bytes to determine how many
partitions.

-Walt Zydhek

-----Original Message-----
From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On
Behalf Of Robert Gault
Sent: Friday, October 18, 2013 7:13 AM
To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] Another Coco Virtual Disk Util

Wayne Campbell wrote:
> It's funny you write this now. It so happens I looked at that earlier 
> today, and I thought it odd that it showed 2 heads for a hard disk.
>
> I have used the same image for all the vhd disks I use. I start by 
> re-formatting the image, then copying files to it from floppy images. 
> So, format is not correcting lsn0?
>
> Wayne

Not sure why these images exist but for LSN0 DD.FMT (byte $10) should be
$82; hard drive one side. I'd bet your value is 3.
In any case, it makes no difference to RGBDOS in MESS or VCC and I don't
know if Walt's program does more than just report it.

You can easily change the value using ded while running NitrOS-9 or with a
PC raw file editor.

Robert



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