Re: MSDOS before cyl 1024

From	Peter 'Shaggy' Haywood <phaywood@alphalink.com.au>
Newsgroups	comp.os.linux.misc
Subject	Re: MSDOS before cyl 1024
Date	2023-01-22 21:33 +1100
Organization	A noiseless patient Spider
Message-ID	<21gv9j-qr1.ln1@jefferson.foo> (permalink)
References	<tqeats$456$4@reader2.panix.com> <lq7cxgrw2k.fsf@mail.soti.ca> <tqglff$2ie4h$5@dont-email.me> <tqgq6a$2k44c$2@dont-email.me> <ea7t9jx7k1.ln2@Telcontar.valinor>

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Groovy hepcat Carlos E.R. was jivin' in comp.os.linux.misc on Sun, 22
Jan 2023 12:52 am. It's a cool scene! Dig it.

> On 2023-01-21 14:43, The Natural Philosopher wrote:
>> On 21/01/2023 12:23, Marco Moock wrote:
>>> Am 21.01.2023 um 03:00:51 Uhr schrieb Vilmos Soti:
>>>
>>>> vjp2.at@at.BioStrategist.dot.dot.com writes:
>>>>
>>>>> What is this about MSDOS partition must be before cylinder 1024?
>>>>
>>>> Old BIOS constraint. Long ago, the BIOS encoded the number of
>>>> heads, cylinders, and sectors in only a few bytes. The cylinders
>>>> were encoded in 10 bits.
>>>>
>>>> This is really old stuff -- maybe 40 year old stuff.
>>>
>>> True, but I dunno when BIOS implementations were changed. I assume
>>> late 90s/early 2000s, but I dunno. Does anybody here know?
>>>
>>>>> How do you know on GParted?
>>>>
>>>> I am surprised that this pops up in 2023.
>>>
>>> Many documentation still mentions that issue, so people ask about
>>> it.
>>>
>> At one level or another faced with a disk the operating system or
>> BIOS needs to know how its laid out so there has to be one hard coded
>> sector - sector zero - to  bootstrap everything. That may contain
>> almost anything, I cant remember the boot sequence on a PC. But it
>> has to be understood by legacy BIOS as well as modern BIOS.
> 
> Old bios and software accessed disks specifying the cylinder, the
> head, and the sector. So does MsDOS.
> 
> Today they only specify the LBA sector.
> 
> Maybe FreeDos can use LBA, dunno.

  In fact, (MS)DOS has supported LBA mode for quite some time. Newer
versions of DOS added support for newer BIOS calls that had extended
(hard) drive support. When LBA support came to the BIOS, it soon came
to DOS too.
  And even before the BIOS and DOS supported LBA, DOS used it
internally, converting LBA values to their CHS equivalents before
calling CHS based BIOS routines.
  And, yes, FreeDOS does indeed support LBA.

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MSDOS before cyl 1024 vjp2.at@at.BioStrategist.dot.dot.com - 2023-01-20 15:10 +0000
  Re: MSDOS before cyl 1024 Marco Moock <mo01@posteo.de> - 2023-01-20 19:04 +0100
  Re: MSDOS before cyl 1024 Vilmos Soti <vilmos@soti.ca> - 2023-01-21 03:00 -0800
    Re: MSDOS before cyl 1024 Marco Moock <mo01@posteo.de> - 2023-01-21 13:23 +0100
      Re: MSDOS before cyl 1024 The Natural Philosopher <tnp@invalid.invalid> - 2023-01-21 13:43 +0000
        Re: MSDOS before cyl 1024 "Carlos E.R." <robin_listas@es.invalid> - 2023-01-21 14:52 +0100
          Re: MSDOS before cyl 1024 Marco Moock <mo01@posteo.de> - 2023-01-21 17:24 +0100
            Re: MSDOS before cyl 1024 "Carlos E.R." <robin_listas@es.invalid> - 2023-01-21 20:32 +0100
              Re: MSDOS before cyl 1024 Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2023-01-21 19:50 +0000
                Re: MSDOS before cyl 1024 "Carlos E.R." <robin_listas@es.invalid> - 2023-01-21 21:16 +0100
                Re: MSDOS before cyl 1024 Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2023-01-21 20:45 +0000
                Re: MSDOS before cyl 1024 The Natural Philosopher <tnp@invalid.invalid> - 2023-01-22 09:39 +0000
              Re: MSDOS before cyl 1024 "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-01-21 15:53 -0500
                Re: MSDOS before cyl 1024 "Carlos E.R." <robin_listas@es.invalid> - 2023-01-22 04:47 +0100
              Re: MSDOS before cyl 1024 The Natural Philosopher <tnp@invalid.invalid> - 2023-01-22 09:35 +0000
                Re: MSDOS before cyl 1024 "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-01-22 05:08 -0500
          Re: MSDOS before cyl 1024 Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2023-01-22 21:33 +1100
            Re: MSDOS before cyl 1024 "Carlos E.R." <robin_listas@es.invalid> - 2023-01-22 14:29 +0100
  Re: MSDOS before cyl 1024 vjp2.at@at.BioStrategist.dot.dot.com - 2023-01-22 20:13 +0000
    Re: MSDOS before cyl 1024 Marco Moock <mo01@posteo.de> - 2023-01-23 10:08 +0100
    Re: MSDOS before cyl 1024 Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2023-01-26 14:40 +1100

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