Re: Why dosemu can not access internal harddisks while running from latest GRML in live CD mode?

[Paul Crawford <psc@sat.dundee.ac.uk>]

Dear Janusz,
> I do not know, how to simulate The boot from The bootable CD or DVD from
> running Dosemu, i did not understand The command sintax for this operation.
> Next isue is, if i will be able to emulate booting from boot media
> successfully, if i will not lost The opportunity to use Speakup screen

I don't think dosemu is the sort of tool that is best suited to testing 
or analysing the boot process of a CD/DVD for operating system recovery.

dosemu does not emulate every feature of a DOS PC, only the ones needed 
so far to run certain DOS programs. As far as I understand it, dosemu 
currently only emulates DMA as used in the sound cards, and not as a 
full PC behaves. If you were to enable direct hard disk access and try 
an operating system it would probably fail as it attempted to switch 
from PIO mode to DMA mode for disk I/O.

I think you should be looking at a 'virtual machine' such as VMware 
(which I have used to run DOS 6.22 and Windows 95 for testing), or one 
of the others such as Zen, VirtualBox, etc:

https://help.ubuntu.com/community/VirtualMachines

I don't know how easy it would be to make a 'live CD' with one package 
installed and configured, so I would suggest installing a Linux 
distribution on a suitable PC, maybe with a new large HDD (couple of 
times the HDD you want to emulate) and plenty of memory (say 512MB plus 
the expected memory for the tested operating system), then installing 
something like VMware player (which is free, but not open source) and 
then trying to create a new blank machine and boot your CD/DVD and see 
if it will restore the 'virtual disk' as you want it to.

The advantage of such an approach is you can simply delete the virtual 
drive and create a new on in minutes, and you can (with some versions) 
create snapshots of the system before installing patches, new software, 
etc, or just to mount them to see what the HDD looked like at that point 
in time.

dosemu is really only for running DOS software that is reasonably well 
behaved. If you do use it for direct hardware access (which we do) then 
it really works best/most reliably for non-operating system components 
such as special peripherals.

Regards,
Paul
-- 
  Dr. Paul S. Crawford
  c/o Satellite Station
  University of Dundee
  Small's Wynd, Dundee, DD1 4HN
  Email: psc@sat.dundee.ac.uk
  Tel: +44 (0)1382 38 4687
  The University of Dundee is a Scottish Registered Charity, No. SC015096