Re: BIOS limits on CD boot ?

From	"wolfgang kern" <nowhere@never.at>
Newsgroups	alt.os.development
Subject	Re: BIOS limits on CD boot ?
Date	2015-06-30 20:03 +0200
Organization	KESYS-development
Message-ID	<mmull1$7nc$1@speranza.aioe.org> (permalink)
References	(4 earlier) <mm3u4m$dou$1@dont-email.me> <mm5dft$i62$1@speranza.aioe.org> <mm6r9r$6eb$1@dont-email.me> <mm8fhi$dgt$1@speranza.aioe.org> <mm8q1s$9lk$1@dont-email.me>

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James Harris wrote":

 
 ...

>>> Wow! I would imagine that that would be a lot of work. The visible CD 
>>> structures are bad enough but then you have to add support for 
>>> mutliple sessions, which are normally masked from us, AFIACS.

>> Try to hide from a machine coder ?
>> yes possible, but not for too long!
 
> When you work out how multiple sessions are laid out do tell. IIRC each 
> session has a long lead-in which is presumably made up of many unused 2k 
> sectors and possibly just continues the sector numbering from where the 
> last session left off (though I am not sure how well it could do that 
> physically).
 
> I see that separate sessions were not part of the original ISO 9660 
> which was for single-session media only. (As I have complained before, 
> the standards that PC people come up with are sometimes lamentable.) I 
> do see that they later came up with something they called "Updatable" or 
> "Multi-Session" ISO 9660 (which is different from the so-called 
> Frankfurt Group Proposal for the same thing. Grr.) Anyway it seems there 
> are relative and absolute LBA addresses which probably apply. I have to 
> say that if later sessions consistently number new sectors to follow on 
> from previous ones that would be easier than I had anticipated.

I checked on bootable CD's created by Nero and figured that this Multi-
session issue is just a matter of not enough memory to write the whole 
CD/DVD at once (ie: the 2GB limit on windoze).

So this Lead IN- lead OUT-sequences may be only required for multi-
session writes (to tell the write-tool where to start next lateron).

Of course a first written image cannot know where following parts 
will reside, even it could calculate that from knowing its own size,
but additive multi-session-records can't be shown in the primary 
volume descriptors and friends ?

I'll check and try in more detail soon ...
__
wolfgang

Thread

BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-19 13:44 +0200
  Re: BIOS limits on CD boot ? "James Harris" <james.harris.1@gmail.com> - 2015-06-19 14:15 +0100
    Re: BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-19 19:07 +0200
      Re: BIOS limits on CD boot ? Melzzzzz <mel@zzzzz.com> - 2015-06-19 19:22 +0200
        Re: BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-20 08:50 +0200
      Re: BIOS limits on CD boot ? "James Harris" <james.harris.1@gmail.com> - 2015-06-20 09:07 +0100
        Re: BIOS limits on CD boot ? "James Harris" <james.harris.1@gmail.com> - 2015-06-20 15:43 +0100
          Re: BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-21 06:10 +0200
            Re: BIOS limits on CD boot ? "James Harris" <james.harris.1@gmail.com> - 2015-06-21 18:13 +0100
              Re: BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-22 09:55 +0200
                Re: BIOS limits on CD boot ? "James Harris" <james.harris.1@gmail.com> - 2015-06-22 12:04 +0100
                Re: BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-30 20:03 +0200
                Re: BIOS limits on CD boot ? "James Harris" <james.harris.1@gmail.com> - 2015-07-01 11:19 +0100
  Re: BIOS limits on CD boot ? "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-06-19 10:56 -0700
    Re: BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-20 08:55 +0200
  Re: BIOS limits on CD boot ? "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-06-19 18:15 -0400
    Re: BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-20 09:18 +0200
      Re: BIOS limits on CD boot ? "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-06-20 07:43 -0700
  Re: BIOS limits on CD boot ? "wolfgang kern" <nowhere@never.at> - 2015-06-21 16:04 +0200
    Re: BIOS limits on CD boot ? "James Harris" <james.harris.1@gmail.com> - 2015-06-22 12:13 +0100

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