🚀 go-pugleaf

In <vanepp.719197327@sfu.ca> vanepp@fraser.sfu.ca writes:

>  doug@cc.ysu.edu (Doug Sewell) writes:
>  
>  >If we do this, then the machine will boot completely from a floppy disk.
>  >But we can't access the hard drive to fix it.  If the HD is configured
>  >in, then the machine will NOT complete a floppy-disk boot.
>  
>  I sent a reply by mail, but maybe it didn't make it. If you can boot from a 
>  floppy, then by using BIOS calls (specifically int26, Absolute disk write)

Sorry, but I think this is wrong. int25/26 do not work without the
disk properly configured, as they need the disk geometry as background
information for calculation of sector numbers. For the same reason,
you can't use DEBUG for raw-read/write on a logically uninstalled
disk. Int13 should do, but best use the already mentioned disk
managers which can access the hardware directly.


>  you should be able to write either 0s or E5s (which I believe is the format
>  data string) onto the first track of the hard disk. This of course will
>  destroy any data on the hard disk, but I assume you don't care. Haveing done

probably you want to save the master boot record (and preferrably the
whole 0th track, which is normally unused but sometimes stores
additional information or boot programs if the master block doesn't
suffice) for later off-line analysis, to see what really happened.

>  that, you should be able to enable the hard drive in the CMOS ram and 
>  partition and format the disk manually.
>  	If there is data you want on the disk, then you might try reading
>  the first few sectors (with int25) to get the partition table and then
>  write a valid partition table from another drive on a working machine onto
>  the broken drive again using int26.

I'm not absolutely sure, but I think that you can't access the
partition table with int25, only the logical drives.

MfG,
        Olaf
-- 
    o     Olaf Titz - comp.sc.student - univ of karlsruhe - germany
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