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Booting from hard disk fails if floppy drives are disabled after installation #21

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andrewbird opened this issue Oct 29, 2017 · 1 comment
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Booting from hard disk fails if floppy drives are disabled after installation #21

andrewbird opened this issue Oct 29, 2017 · 1 comment

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@andrewbird
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If PC-MOS is installed from floppy disk to hard disk after which the floppy disks are disabled, booting from the hard disk is no longer possible as the boot process becomes confused about the location of command.com. There's a long discussion over at dosemu2/dosemu2#502, where it seems that although $MOS.SYS wants to open C:\COMMAND.COM, C: is no longer deemed valid as in the MOS BDB linked list the only drive is number '00'. This is the result:
pcmos-no-floppy-with-bootblk
stsp added a commit to stsp/pcmos386v501 that referenced this issue Nov 5, 2017
@stsp
MOSDDBLK: always reserve 2 drives for floppies [fixes roelandjansen#21]
bf31496 
This is a quick-fix that prevents HDD from moving to A:.
It is not clear why HDD does not work on A:, maybe it should?
Maybe someone else can code up the more intrusive fix.
stsp added a commit to stsp/pcmos386v501 that referenced this issue Nov 5, 2017
@stsp
MOSDDBLK: always reserve 2 drives for floppies [fixes roelandjansen#21]
1f1d7ce 
This is a quick-fix that prevents HDD from moving to A:.
It is not clear why HDD does not work on A:, maybe it should?
Maybe someone else can code up the more intrusive fix.
@roelandjansen
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thanks for the feedback

roelandjansen added a commit that referenced this issue Nov 14, 2017
@roelandjansen
Merge pull request #23 from stsp/flp_fix
21517ed 
MOSDDBLK: always reserve 2 drives for floppies [fixes #21]
the-grue added a commit to the-grue/pcmos386v501 that referenced this issue Aug 10, 2019
@the-grue
MOSDDINT: invalidate 2 drives if no floppies [fixes roelandjansen#21]
325386e 
If no floppies are installed, MOS should invalidate first 2
drives, see roelandjansen#23

Re-applied as it was removed as part of code audit.  Discovered
in v5.02 GA.  Original fix by @stas.
the-grue added a commit to the-grue/pcmos386v501 that referenced this issue Aug 10, 2019
@the-grue
make number of boot HDD configurable
a5979ca 
    This patch extends e543c1f3 to allow any boot HDD from A to C.
    It unhardcodes the value "2" for boot HDD in MOSINIT2.ASM.
    This change does not affect the floppy boot because of:

    test al,80h ; hard drive?
    jz doflpy   ; no

    in boot code.
    The number of floppies is saved into "sbcflops" var, and is
    currently not used anywhere. This is for further extensions.
    I had no success in booting from drives past C but this is
    unlikely being of any importance.

    Re-applied as it was removed as part of code audit.  Discovered
    in v5.02 GA.  Original fix by @stsp.

Also includes fix:

   MOSDDINT: invalidate 2 drives if no floppies [fixes roelandjansen#21]
    If no floppies are installed, MOS should invalidate first 2
    drives, see roelandjansen#23

    Re-applied as it was removed as part of code audit.  Discovered
    in v5.02 GA.  Original fix by @stsp.
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@andrewbird @roelandjansen