Mail Archives: opendos/2000/10/30/01:37:11
See below ...
Joe.
> -----Original Message-----
> From: Patrick Moran [SMTP:pmoran22 AT yahoo DOT com]
> Sent: Friday, 27 October 2000 7:01
> To: opendos AT delorie DOT com
> Subject: Re: DRDOS FDISK
>
---- snip ----
> other OSes can use logical drives in an extended partition. However,
> people
> having older mother boards with older BIOS have a limit of 1024 cylinders
> in
> which you may boot from. So often times people will make small primary
> partitions so that the boot files needed to boot the OS will be within the
> first 1024 cylinders of a drive. For example. a lot of people make a small
> primary partition for the Linux /boot directory of about 8MB and install
> LILO in that boot record and make sure thst the entire partition is within
> the first 1024 cylinders. The OS/2 boot manager or any other boot manager
> must be within the first 1024 cylinders. In later BIOS, you do not need to
> worry about this. many people are still using 286/386/486 machines and
> most
> of these BIOS have this limitation. Many of the Pentium I and II system
> may
> also have this limitation. It would cost more to update these BIOS than it
> would cost to get a good late model new or used motherboard.
>
> I don't know what the limitation is on my BIOS, but all my drives are less
> than 1024 cyl or they lie to the BIOS and show less than 1024. Some people
> even run much older systems such as 8088/80286 and would rather run DOS
> 3.3
> on them. MSDOS 3.3 has a maximum size of 32MB per primary or logical
> drive.
> Nobody I know uses MSDOS 4.0.) The reason they do this is because the
> system
> files and many of the DOS files are much smaller and take less disk space.
>
---- snip ----
[da Silva, Joe]
Actually, it's not the drive that lies to the BIOS (well, it does
that too,
but that's a different story), it's the BIOS that lies to the O/S.
For recent
BIOSes, when you select either Extended (IIRC) CHS, or LBA settings,
what you are saying is for the BIOS to translate O/S (Int 13) CHS
parameters to/from either the Extended CHS or LBA parameters of the
drive. For older BIOSes, you need to load a sort of patch to the
BIOS,
in the MBR, using Disk Manager or equivalent. This allows the O/S to
break the 504M limit (to 8G), while still operating within the Int
13 limit
of 1024 cylinders. I don't know for sure, but I think the current
versions
of Disk Manager also add Extended-Int13 services to the BIOS to
break
the 8G limit (for suitable O/S only, eg. M$DOS 7.10).
As for using M$DOS 3.3 to avoid bloat, I would recommend instead,
DR-DOS 6. This gives you partitions of up to 2G (instead of just
32M),
has reasonable memory support (note - it's EMM386 has very *good*
compatibility with app's :-), yet has nice, compact executables.
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