Xref: utzoo comp.unix.sysv386:7872 comp.unix.xenix.sco:2463 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!wuarchive!uunet!mcsun!unido!opal!gmdtub!prosun!tmh From: tmh@prosun.first.gmd.de (Thomas Hoberg) Newsgroups: comp.unix.sysv386,comp.unix.xenix.sco Subject: Re: booting DOS on ISC+SCO, and DOS filesys handling (long-ish) Message-ID: <639@bigfoot.first.gmd.de> Date: 7 May 91 16:10:43 GMT References: <1991Apr24.074220.17639@jet.uucp> Sender: news@bigfoot.first.gmd.de Reply-To: tmh@prosun.first.gmd.de (Thomas Hoberg) Followup-To: comp.unix.sysv386 Organization: GMD-FIRST, D-1000 Berlin 10 Lines: 87 In article <1991Apr24.074220.17639@jet.uucp>, cm@jet.uucp (colin manning) writes: |> Ideally, there would not be all these seemingly unnecessary restrictions |> concerning support for different partition types, sizes etc. In my opinion, |> whoever designed the fdisk partition table structure left a lot to be |> desired - why only allow at most 4 partitions on a drive ? and why restrict |> the cylinder numbers to 10 bits ? It seems to me that to have allowed a |> reasonable number of partitions (say 32) and to use 32 bit disk addressing |> would not have been too hard. The cost would have been, say, an additional |> 256 bytes or so to save a lot of hassle. I thank God they included the partition table at all. Remember that the partition table first appeared on the IBM PC/XT with DOS 2.0. The XT had a 10MB hard disk and for operating systems there was DOS, DOS and DOS. CP/M-86 was dying and Xenix was "announced" (it never *really* materialzed for the 8088, just like the multi-tasking DOS 2.5) |> |> Also, why is it that support for DOS 4 partitions is non-existant in ISC and |> SCO ? DOS 4 seems to have been around for quite long enough for support to |> have been added. Most people could live with 32MB DOS partitions and many without any. |> |> Anyway, I'd be interested in information on any of the following. I'll |> post a summary in due course if there's sufficient interest. |> |> 1. Is it possible to have an easy way of selecting between booting DOS |> or Unix on an ISC system, without having to remember to use fdisk |> every time to change the active partition ? Ideally the source to |> a boot program that could be put on a primary DOS partition would |> be nice (like the one I use with SCO). I posted a partition booter some time ago, but BOOTMENU seems to have take over the market. |> 2. Although ISC and SCO do not seem to have any support for >32Mb DOS 4+ |> filesystems: |> i. When is support for these expected from ISC and SCO ? Perhaps never, but while they are at it, why not add High Sierra, HPFS, Mac-FS, VMS, 370, Cyber, creeping featureism and melancholia. |> ii. When you use SCO, and you interrupt the auto-boot to boot DOS (by |> typing 'dos' at the : prompt), will it boot correctly off a >32Mb |> DOS 4 partition ? I hope so. |> iii. If you try to have >32Mb DOS 4 partitions on a SCO or ISC system, |> does the Unix safely ignore them even though they cant use them ? |> Yes |> 3. Is it possible to have both SCO and ISC Unix on the same machine, in |> different partitions, and have some way of selecting between the 2 |> at boot time ? ISC (and DOS 5) depend on their partitions to be active to boot. I don't know about SCO. If your partition booter rewrites the partition table it should work. |> |> 4. Does ISC recognise SCO partitions and vice-versa ? Both recognize Xenix file systems. ISC FFS and SCO 1k file system might use different magic numbers. |> |> Many thanks in advance, |> |> -- |> - Colin Manning, cm%jet.uucp@ukc.ac.uk (world) OR cm@jet.uucp (UK only) |> - Disclaimer: Please note that the above is a personal view and should not |> be construed as an official comment from the JET project. -- tom ---- Thomas M. Hoberg | UUCP: tmh@bigfoot.first.gmd.de or tmh%gmdtub@tub.UUCP c/o GMD Berlin | ...!unido!tub!gmdtub!tmh (Europe) or D-1000 Berlin 12 | ...!unido!tub!tmh Hardenbergplatz 2 | ...!pyramid!tub!tmh (World) Germany | BITNET: tmh%DB0TUI6.BITNET@DB0TUI11 or +49-30-254 99 160 | tmh@tub.BITNET