[cctalk] Re: Disk imaging n00b

3 Nov 2022

...
 > But, why do IMAGING on PC-DOS disks? 
On Thu, 3 Nov 2022, Grant Taylor via cctalk wrote:
...
  My /personal/ and primary use case is for use in
virtual machines where disk 
 images (a la dd) is best (in my experience). 
THAT is a totally valid reason for disk images, rather than file copies.

Another, less common problem, is that SOME installation programs also look 
at the disk label, in addition to the files.
Windoze, at least in 3.xx did not.  It worked fine to copy everything to a 
single directory and install from there.

...
   Other than
bootable or copy-protected, then re-creation is format a disk 
 and copy the files onto it.  I largely agree.  However being a person that plays
with different operating 
 systems in virtual machines, I need to boot and / or readily attach images to 
 the VM. 
Ah, if you are using OS's other than MS-DOS and PC-DOS, then a disk image 
is likely to be essential.
Even the 5150 also had CP/M-86 and UCSD P-System FROM IBM.
And the 5170 had Xenix (Santa Cruz Operation Unix, peddled through 
Microsoft)

...
   In what way
would "better than DD" be needed?  I'm too ignorant to be able to
answer that.  dd has served /my/ needs. 
 However I think there is some consensus, I don't know how general it is, that 
 dd or simple file copy tends to not be sufficient for some things. 
The USUAL reasoning is to reproduce variance other than content of sectors 
and files.  Such as copy-protection.

Unless you are dealing with copy-protection, or seriously alien formats, 
you are generally better off using the FDC to make your images, rather 
than flux-transition.  There are numerous FDC based imaging programs, but, 
there are also multiple formats of the image, such as metadata headers, 
etc.

OTOH, flux-transition lets you look at content below the sector level, to 
view and sometimes even repair damaged tracks.

...
  I believe it's technically possible to re-create
an MS-DOS boot disk by 
 formatting and then copying IO.SYS, MSDOS.SYS, and then COMMAND.COM to the 
 floppy disk in that order.  I think the same methodology can be used with 
 PC-DOS.  But that's /just/ /DOS/ and doesn't cover boot disks for other 
 operating systems that I play with. 
Even with MS-DOS/PC-DOS, there CAN [very rarely] be issues of boot sector.
OS other than MS-DOS/PC-DOS likely need an image.  SOME OS use system 
tracks and/or content that is NOT stored as files in the DIRectory.

--
Grumpy Ol' Fred     		cisin(a)xenosoft.com

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[cctalk] Re: Disk imaging n00b