mfrohman@digi.lonestar.org (Matthew Frohman) (10/04/90)
I am using MicroPort's implementation of Unix (sys V/386).
I have a 386/20 with a 67 MB hard disk and 5 MB of RAM.
When I install the software, it asks me if I want to save
a part of the hard disk for DOS. When I reply YES, it asks
me for the number of cylinders, 0-644. However much I
allocate, it place DOS as the first partition, starting at 1,
with the Unix partition following.
My question is, according to the documentation, NO partition
should begin at 0 or 1. That is reserved for something else.
I see no way to specify where to begin the partition.
It IS causing a problem, because after I install Unix, then
go back to DOS and format the DOS drive and set it as the
active partition, the next time I turn on my computer, the
boot sector has been wiped out and FDISK says that there are
NO partitions.
Any help???
--
----------------------------------------------------------------------------
Matthew Frohman texbell!digi!mfrohman OR mfrohman@digi.UUCP
OR mfrohman@digi.lonestar.org
----------------------------------------------------------------------------tony@mcrsys.UUCP (Tony Becker) (10/05/90)
From article <1071@digi.lonestar.org>, by mfrohman@digi.lonestar.org (Matthew Frohman): > I am using MicroPort's implementation of Unix (sys V/386). > ... > However much I > allocate, it place DOS as the first partition, starting at 1, > with the Unix partition following. This is a DOS thing, It must be the first partition. > > My question is, according to the documentation, NO partition > should begin at 0 or 1. That is reserved for something else. > I see no way to specify where to begin the partition. The first (0) sector (not partition) is the boot sector, followed by the fdisk info, I believe. Partitions don't start until the second track, which depends on your drive's sectors/track. > It IS causing a problem, because after I install Unix, then > go back to DOS and format the DOS drive and set it as the > active partition, the next time I turn on my computer, the > boot sector has been wiped out and FDISK says that there are > NO partitions. Gotcha! 1) make sure you don't allocate more then 32Mb (dos limit) of cyls to the Unix partitioner. 2) format the dos partition with dos 3.21-3.3 only. DOS4.01 may over-write the UNIX fdisk info. 3) DO NOT change the fdisk info with ANYTHING other then the original program, in this case, the UNIX partitioner. Note that if you change from Unix to dos as the active partition, you can't get back. 4) if you must boot dos, use a floppy. set up an autoexec.bat on the dos partition that sets the path and COMSPEC to C:... This feature? is do to the fact that the boot sector anf fdisk info are tied together AND that microsoft changed them from rev to rev of dos. for the sake of argument the Microport's partitioner is DOS 3 compatible. by sys-ing or fdisk-ing from dos, you run the risk of confusing either the boot code, or the fdisk info it uses. ******************************************************************************* | \ / | /=| /=| Tony Becker MCRSYS Florida \ \ / / || || uunet!mcrsys!tony (813) 799-1836 (voice) \ \ / / || || \ \/ / || || Opinions expressed are my own, and don't \ / || || necessarily reflect those of any other / \ || || members of my species. / /\ \ || || -It's nice to live in a society where this / / \ \ || || is possible, and not a capital crime! / / \ \ || || | / \ | |====| |====| *******************************************************************************
rbj@druhi.ATT.COM (Russell B. Jorgensen) (10/05/90)
in article <1071@digi.lonestar.org>, mfrohman@digi.lonestar.org (Matthew Frohman) says: > > It IS causing a problem, because after I install Unix, then > go back to DOS and format the DOS drive and set it as the > active partition, the next time I turn on my computer, the > boot sector has been wiped out and FDISK says that there are > NO partitions. > > Any help??? > -- > ---------------------------------------------------------------------------- > Matthew Frohman texbell!digi!mfrohman OR mfrohman@digi.UUCP > OR mfrohman@digi.lonestar.org > ---------------------------------------------------------------------------- I don't recall ever having a problem starting a DOS partition on cylinder 0, but I'm running on a 286 system. I wouldn't think it would make a difference, though, since DOS is DOS is DOS ... However, to overcome your immediate problem, when you install UNIX, you can allocate a DOS partition 2 cylinders larger than you need, then go back with fdisk to delete the DOS partition, and re-create it with the correct size starting at cylinder 2. I would think this would keep anything from scribbling on the first two cylinders. Russ Jorgensen AT&T Bell Laboratories Denver, CO
cpcahil@virtech.uucp (Conor P. Cahill) (10/06/90)
In article <15@mcrsys.UUCP> tony@mcrsys.UUCP (Tony Becker) writes: >From article <1071@digi.lonestar.org>, by mfrohman@digi.lonestar.org (Matthew Frohman): >> However much I >> allocate, it place DOS as the first partition, starting at 1, >> with the Unix partition following. > >This is a DOS thing, It must be the first partition. No, it is actually a UNIX thing. DOS doesn't care where it sits on the disk drive as long as the fdisk table correctly maps it out. UNIX usually enforces that DOS be first because it then allows unix to use up the rest of the disk (including any cylinders beyond 1024 - which doss couldn't access) >1) make sure you don't allocate more then 32Mb (dos limit) of cyls to > the Unix partitioner. should be "to the DOS partition when using the Unix partitioner" >4) if you must boot dos, use a floppy. set up an autoexec.bat on the dos > partition that sets the path and COMSPEC to C:... I know many people that have a program/shell that changes the "active" partition and reboots the system so that they can reboot to dos and vice-versa. -- Conor P. Cahill (703)430-9247 Virtual Technologies, Inc., uunet!virtech!cpcahil 46030 Manekin Plaza, Suite 160 Sterling, VA 22170
pjh@mccc.uucp (Pete Holsberg) (10/07/90)
In article <1990Oct06.123144.10914@virtech.uucp> cpcahil@virtech.UUCP (Conor P. Cahill) writes:
=I know many people that have a program/shell that changes the "active"
=partition and reboots the system so that they can reboot to dos and
=vice-versa.
Do you think that one of them would be willing to share his/her code
with us? Does one of them have a "screen blanker" of the sort that
turns off the screen after N minutes of no keystrokes at the console? Thanks.
Pete
--
Prof. Peter J. Holsberg Mercer County Community College
Voice: 609-586-4800 Engineering Technology, Computers and Math
UUCP:...!princeton!mccc!pjh 1200 Old Trenton Road, Trenton, NJ 08690
Internet: pjh@mccc.edu Trenton Computer Festival -- 4/20-21/91mfrohman@digi.lonestar.org (Matthew Frohman) (10/08/90)
>From my original posting. . . >> I am using MicroPort's implementation of Unix (sys V/386). >> ... >> >> My question is, according to the documentation, NO partition >> should begin at 0 or 1. That is reserved for something else. >> I see no way to specify where to begin the partition. >> >> It IS causing a problem, because after I install Unix, then >> go back to DOS and format the DOS drive and set it as the >> active partition, the next time I turn on my computer, the >> boot sector has been wiped out and FDISK says that there are >> NO partitions. Well, I stumbled across the answer myself. Thanks for all of the responses, but the correct answer is the following: The disk is formatted with the first partition as DOS and the second as UNIX. If you are running UNIX and wish to change the active partition, you MUST use the UNIX FDISK. If you are using DOS and wish to change the active partition, you MUST use the DOS FDISK. I had been running under UNIX and I placed an MS-DOS boot disk in drive A and reset the machine. After is booted, I used the DOS FDISK to change the active partition. Oh well. . . I didn't know any better at the time.-- ---------------------------------------------------------------------------- Matthew Frohman texbell!digi!mfrohman OR mfrohman@digi.UUCP OR mfrohman@digi.lonestar.org ----------------------------------------------------------------------------
ie43gn1f@dingbat.fiu.edu (Student - 44) (10/10/90)
I think there is a myth about DOS4.0 and greater and Unix partitions. Despite what the documentation said, I was able to successfully install SCO Unix and DOS 4.01 on the same drive, both with bootable partitions. Maybe Dos got smart?! Unix partitions use sector 0, if possible, set up the DOS partition to start at 1. DOS 4.01 didn't give me any choice, and it worked out ok... Wolf
plocher@sally.Eng.Sun.COM (John Plocher) (10/11/90)
| > My question is, according to the documentation, NO partition | > should begin at 0 or 1. That is reserved for something else. | > I see no way to specify where to begin the partition. | | The first (0) sector (not partition) is the boot sector, | followed by the fdisk info, I believe. Partitions don't | start until the second track, which depends on your drive's sectors/track. I see by other messages that your other questions were answered, so I won't address them. But.... A) Your documentation is wrong and B) The reply you got is wrong. The MBB (Master Boot Block) is located at [0,0,0] (that is, cyl 0, head 0, sector 0) It looks like this: Byte 0 +---------+ | Boot | | code | | | ~ ~ | | |---------| |partition| | table | 512 +---------+ The IBM documentation (the one that counts :-) states that all partitions start at [*,0,0] except the first, which starts at [0,0,1] (because, of course, the MBB is already using [0,0,0] :-). The MBB boot code simply scans the partition table for the active partition's starting location, loads in the first block found there at a well known address (which, of course, I forgot), and jumps to it. This PBB code (Partition Boot Block) then does whatever is needed to bootstrap the OS that lives on that partition - like loading in the MSDOS.SYS file or the Microport Unix secondary boot code. In the uport case, this secondary boot code is what looks for, loads, and starts running the /unix program. More senile ramblings from -John Plocher
tim@maths.tcd.ie (Timothy Murphy) (10/13/90)
In <15@mcrsys.UUCP> tony@mcrsys.UUCP (Tony Becker) writes: >3) DO NOT change the fdisk info with ANYTHING other then the original > program, in this case, the UNIX partitioner. Note that if you change > from Unix to dos as the active partition, you can't get back. This isn't true in my experience. There is no problem at all in re-setting the active partition to Unix within DOS, and rebooting. In fact I do it both ways regularly. -- Timothy Murphy e-mail: tim@maths.tcd.ie