From owner-freebsd-questions@freebsd.org Wed Oct 17 08:07:32 2018 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 1196A10CC9C1 for ; Wed, 17 Oct 2018 08:07:32 +0000 (UTC) (envelope-from smithi@exemail.com.au) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 8D576755BC for ; Wed, 17 Oct 2018 08:07:31 +0000 (UTC) (envelope-from smithi@exemail.com.au) Received: by mailman.ysv.freebsd.org (Postfix) id 4EEE610CC9BE; Wed, 17 Oct 2018 08:07:31 +0000 (UTC) Delivered-To: questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 2D39410CC9BD for ; Wed, 17 Oct 2018 08:07:31 +0000 (UTC) (envelope-from smithi@exemail.com.au) Received: from mail109.syd.optusnet.com.au (mail109.syd.optusnet.com.au [211.29.132.80]) by mx1.freebsd.org (Postfix) with ESMTP id 76126755B9 for ; Wed, 17 Oct 2018 08:07:30 +0000 (UTC) (envelope-from smithi@exemail.com.au) Received: from [10.40.157.238] (pa49-195-178-119.pa.nsw.optusnet.com.au [49.195.178.119]) by mail109.syd.optusnet.com.au (Postfix) with ESMTP id E5615D66C37; Wed, 17 Oct 2018 19:07:14 +1100 (AEDT) Date: Wed, 17 Oct 2018 19:07:08 +1100 User-Agent: K-9 Mail for Android In-Reply-To: <20181015115900.4142cede.freebsd@edvax.de> References: <50139023-EF23-4464-8E99-4958CB3A3044@exemail.com.au> <20181015115900.4142cede.freebsd@edvax.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: FreeBSD boot manager customization for single-disk multiboot (4 x DOS) To: Polytropon CC: questions@freebsd.org From: Ian Smith Message-ID: X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.2 cv=DZtnkrlW c=1 sm=1 tr=0 a=hDAvsFtYMuZurM1Ov3B5KQ==:117 a=hDAvsFtYMuZurM1Ov3B5KQ==:17 a=IkcTkHD0fZMA:10 a=x7bEGLp0ZPQA:10 a=asWo_369AAAA:8 a=zPhsVytCAAAA:8 a=92Z_Rc3yAAAA:8 a=HLTLLJWx-uXZVbMFMyMA:9 a=T2wH237lBQYjmKvn:21 a=bybI-AKwqtIAd1h2:21 a=QEXdDO2ut3YA:10 a=hMgRPY4v-A8A:10 a=YnP8LtLWTqQO9u8dPMSg:22 a=7wv77BxldzPusDp5tRd2:22 a=v3jhTiZ8Tly5EgMBTjSd:22 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 17 Oct 2018 08:07:32 -0000 On 15 October 2018 8:59:00 pm AEDT, Polytropon wrote: > On Mon, 15 Oct 2018 19:28:55 +1100, Ian Smith wrote: > > I've read the thread=2E Manish is trying to help but his DOS > > familiarity doesn=E2=80=99t go back far enough=2E I started at 2 and > > used 3=2E3 (with Desqview), later 5=2E0 for years running Fidonet > > mailer, BBS, message editor, DOS command space and other tasks > > in 6 MiB RAM =2E=2E so had to learn how to really squeeze things > > in - as did you, I gather=2E=20 >=20 > Correct=2E Started with DOS 3=2E3 (and its "foreign predecessors" > called SCP and DCP which aren't known outside former GDR), then > DOS 5=2E0 and 6=2E22 (with NDOS as COMMAND=2ECOM replacement), and > I even used Novell DOS 7 for a short time (and its UNDELETE > program was really great)=2E Oh, and I also know and still _have_ > Desqview/X (with package, books, and floppies)=2E >=20 >=20 >=20 > > Correct, you cannot boot DOS from a non-primary partition=2E > > Maybe you could use GRUB, it installs after the MBR on track > > 0 side 0 so shouldn't get in the way=2E >=20 > I think an older version of Grub might work - I don't assume > today's current version is up to the task on running on such > an old system=2E >=20 >=20 >=20 > > I dont think you need to install linux to install GRUB? >=20 > The smallest disk that I can use is 20 GB, so it would not > be a problem due to space limitation if I installed Linux=2E > For "logical space", it could even go into an extended > partition, for example like this >=20 > Whole disk: 20,000 MB >=20 > prim=2E part=2E 1 =3D DOS 5=2E0 50 MB > prim=2E part=2E 2 =3D DOS 6=2E22 500 MB > prim=2E part=2E 3 =3D data exchange (FAT) 1,000 MB > ext=2E part =3D { > log=2E vol=2E 1 =3D Windows '95 2,000 MB > log=2E vol=2E 2 =3D Windows '98 2,000 MB > log=2E vol=2E 3 =3D Linux swap 2,000 MB > log=2E vol=2E 4 =3D Linux ext2 12,000 MB > } >=20 > Disk space is not a problem=2E The replacement system does not > accept disks bigger than 20 GB, so when I say "smallest disk", > this is actually the only (!) disk I can use=2E :-) >=20 >=20 >=20 > > That said, I don't use it myself=2E To add linux to the 4-DOS > > mix would need an extended partition, leaving only 3 primaries > > for 3 x DOS=2E Same deal with OS/2, with its great boot manager=2E >=20 > Oh yes, OS/2=2E=2E=2E it wrecked my DOS installation and "shifted" > the partitions (3 became 2, 2 became 1, 1 disappeared) when > I tried to install it into partition 4=2E Luckily, with the > great Norton Disk Editor (run from DOS emergency floppy), > a handheld calculator, and pen & paper I could reconstruct > the partition table manually and "get my data back" (as it > was not overwritten, just not assigned to a partition anymore)=2E >=20 >=20 >=20 > > boot0=2Es MBR code is VERY tight with about ZERO free space as > > I recall =2E=2E however there's code there - still was at 9=2Ex I > > think - for a 1=C4=B6 (2 sector) version written by the same author > > (Robert Nordier IIRC, I don't have a system to hand)=2E That > > should have plenty of room for more lavish labels, and may > > in fact include such code? If you have a spare system you > > could assemble that and test=2E >=20 > I haven't done assembly programming for many years=2E I can > generally understand how the boot manager works, but I don't > think I'm skilled enough for modifying it (and still get a > working version that can do what I expect)=2E The detection > and labeling magic is quite powerful in there=2E :-) >=20 >=20 >=20 > > Of course you'll have a backup MBR (directed more at other readers > :) >=20 > Luckily, that is an easy task with dd=2E In DOS, C, you'd use > the famous biosdisk() (prototype in dos=2Eh!) to get the 512 > bytes from the disk and store it to a file=2E >=20 > That reminds me to one of my first exercises in lower-level > C programming: Wrote a program that would modify the MBR to > change the start address of the 1st active primary partition > to the MBR itself, so the system would "boot into a loop"=2E > Yes, we did actually consider this both funny and educational > at that time=2E=2E=2E :-) >=20 >=20 >=20 > > One thing to watch is that esp=2E earlier versions of DOS may > > want to use the first slice explicitly? I'm not sure, but I'd > > start with earliest versions first, and test each as you go=2E=20 >=20 > Yes, I think DOS 3=2E3 and before specifically needed that=2E > I'll check how DOS 5=2E0 will react=2E From older experience, > I seem to remember that DOS 6=2E22 could be booted from a > primary partition 2, 3, or 4, and depending on the content > of the ramining partitions, "drive letters" would then be > re-arranged (as the boot disk would always be C: as assigned > by a boot manager)=2E >=20 >=20 >=20 > Interestingly, I found out that I could _maybe_ fix the > power supply of the IBM Thinkpad 755C=2E Documentation says > that it needs 20 V DC (so no 10 V DC as written on the label > of the exploded power supply)=2E I think I still have a PSU > "brick" that provides 20 V DC, and making a new cable from > the remains of the old PSU is not a problem=2E >=20 > /-------\ > + --- | o o | --- Signal > - --- | o o | --- Ground > +-------+ >=20 > Documentation suggests that "+" and "-" are the ones that > should be used, and _not_ connected to "S" and "G" in any > way=2E In case you are curious, this is the relevant documentation > that gave me hope to revive the TP 755C that has served me > so well for decades: >=20 > http://www=2Ethinkwiki=2Eorg/wiki/Power_Connector#4-Pin_hexagon >=20 > https://www=2Epowerstream=2Ecom/lta-IBM=2Ehtm >=20 > It looks like this one: >=20 > http://www=2Ethinkwiki=2Eorg/w/images/9/9f/ThinkPad755CD=2Ejpg >=20 > But instead of the optical unit, mine has the floppy disk > unit installed=2E And as I said, having access to old-fashioned > things like parallel ports, serial ports, or floppy drives > sadly is _not_ optional in this special case=2E :-) I'd have replied interspersed in my usual manner, but it's just too tediou= s on this little phone; please excuse=2E At least K9 can bottom-post =2E= =2E trim at will =2E=2E As mentioned, I have no access to a system currently - except I remembered= having ssh access to an ancient but still working 5=2E5-stable (cough) wit= h src, so I reviewed (from /usr/src): =2E/usr=2Esbin/boot0cfg/boot0cfg=2Ec =2E/sys/boot/i386/boot0/boot0=2ES =2E/sys/boot/i386/boot0/boot0ext=2ES =2E/sys/boot/i386/boot0/Makefile You'll note that adding longer labels for more OS types is the significant= difference between the two and that boot0cfg(8) -b option can choose betwe= en (eg) boot0, boot0sio and, while not mentioned explicitly, boot0ext if ac= cessible=2E=20 Check out the boot0ext code=2E On 5=2E5 it's not assembled, or at least n= ot copied into /boot=2E Not sure if this is still in 10=2Ex and up=2E Some here and certainly many on hackers@ could advise on having it also bu= ilt to /boot (or anywhere) for boot0cfg access=2E I assume you could dd it= from a memstick into place, that is if the machine can boot from USB memst= ick? Or floppy!? Now, even then you won't get distinctions like between DOS or windows vers= ions, have a look at the table in boot0ext=2E It looks easy enough to chan= ge the strings if adjusting relative offsets=2E boot0 doesn't even distinguish between DOS and windows, not at FreeBSD 8= =2E2 anyway; I have a win98 on one, labeled as DOS (only for BIOS updates i= n the past)=2E Are you sure w95 and w98 can boot from an extended partition? XP can - it'= s an NT or OS/2 filesystem - but w95/98 is 'DOS 7' so I'd test that assump= tion unless you're sure=2E US$67=2E50 is a lot for an external P/S brick=2E I bought 2 broken thinkp= ad T23s for AU$60 (~US$45) posted, off ebay years ago, with 2 working 65W P= /S, 1 good screen, 2 good 60G disks, 2 good keyboards (albeit one GB/UK) an= d importantly for T23s, 2 working CPU fans :) I bet you'd find a 755C, broken or not, for 50DM or less with a working P/= S and maybe other useful spares? Otherwise you have the plug, so wiring up another P/S brick should be ok w= ith care=2E Looks like going for 50W or more would be safest=2E=20 "it's the options that drive ya crazy" cheers, Ian