News Group Posts

biosgeom 1023 cylinder boot

This kind of problem doesn't exist in modern computer equipment but I leave it here for historical interest.

From: buckler@yahoo.com (Dan Buckler)
Newsgroups: comp.unix.sco.misc
Subject: Re: 1023 Cylinder Limit
Message-ID: <38b8aee5.27207581@localhost> 
References: <886alq$9rd$1@neptunium.btinternet.com>
<38A6AF47.B0A208F9@aplawrence.com>
<8871b1$1n0$1@neptunium.btinternet.com> 
Date: Sun, 27 Feb 2000 05:03:21 GMT

The problem you cite is limited to IDE or ATA hard drives as far as I
know. The root of the problem is the CHS addressing scheme 
(Cylinder - Head - Sector). The problem is that the number of bits 
need to represent the number of Cylinders exceeds the number of 
bits set aside for this purpose in the bios. To overcome this problem
the ATA hardware vendors introduced LBA (Logical Block Addessing)
To make SCO work 5.0.5 work is not very hard actually. Try this:

1) find out the number of cylinder, heads and sectors from reading the

    top of the drive, or from the drive vendors web site.

2) Do this at boot prompt: (substiture the values you found)

        boot
        : defbootstr biosgeom=(#cyl, #heads, #sectors)

- Dan

On Sun, 13 Feb 2000 19:39:07 -0800, "Steve Morris"
<Stephen.Morris@btinternet.com> wrote:

>Thanks for claryfying this for me.
>
>Looking at Adaptecs UNIX Q & A web page, they say that cylinder 1023 falls
>withing the first 1Gb of disk space. If this is the case, then I am going to
>have to re-install all my Windows stuff again.
>
>Does this sound right to you - do you have any suggestions?
>
>Thank you.
>
>--
>Regards
>
>Steve
>"Tony Lawrence" <tony@aplawrence.com> wrote in message
>news:38A6AF47.B0A208F9@aplawrence.com...
>> Steve Morris wrote:
>>
>> > This apparently relates to an old limitation that I was aware of years
>ago
>> > with regard to the root filesystem having to reside with the first 1023
>> > cylinders of your hard disk.
>> >
>> > However, I had thought that by the  release of 5.0.5 that this would've
>been
>> > a thing of the past.
>>
>> It's nothing to do with OSR5.  That's a BIOS limitation,
>> period.   In other words, the hardware is at fault, not SCO.
>>
>> --
>> Tony Lawrence (tony@aplawrence.com)
>> SCO/Linux articles, help, book reviews, tests,
>> job listings and more : 
>>
>
>--
>Regards
>
>Steve
>"Tony Lawrence" <tony@aplawrence.com> wrote in message
>news:38A6AF47.B0A208F9@aplawrence.com...
>> Steve Morris wrote:
>>
>> > This apparently relates to an old limitation that I was aware of years
>ago
>> > with regard to the root filesystem having to reside with the first 1023
>> > cylinders of your hard disk.
>> >
>> > However, I had thought that by the  release of 5.0.5 that this would've
>been
>> > a thing of the past.
>>
>> It's nothing to do with OSR5.  That's a BIOS limitation,
>> period.   In other words, the hardware is at fault, not SCO.
>>
>> --
>> Tony Lawrence (tony@aplawrence.com)
>> SCO/Linux articles, help, book reviews, tests,
>> job listings and more : 
>
>

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