VOGONS


First post, by PlaneVuki

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Hi!

Sorry if this has been asked before or a very silly question.

DOS6.22 supports hard drive (or partition) up to 2gb.

So if I have a 3.2gb hard drive,

It will have problems with since thats bigger than 2gb,

But if I make two partitions, each 1.6gb, can I use whole hard drive capacity like this without problem?

Thanks in advance.

Reply 1 of 12, by Jorpho

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But of course. That is a slightly silly question.

Note that you will want to create two primary partitions, as opposed to one primary partition and one extended partition (with a logical partition therein).

With two primary partitions, you can even use the "active" flag to toggle which one you want to boot from.

Reply 2 of 12, by megatron-uk

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Yes. You can split it into 1.6 and 1.6, or 2 and 1.2, or anything you want really, as long as you don't go over 2gb for any single partition.

Without mods, Dos 6.22 can use drives up to 8gb in size. The biggest layout you could have in that case is 4x 2gb partitions.

You can have up to 4 primary partitions on the disk, or you can create a single primary partition and then any number you like (within the limits of available drive letters and base memory for your lastdrive statement!) of logical partitions in a extended partition to contain them.

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Reply 3 of 12, by Mister Xiado

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Of course, if you want to go crazy and pop in a 60GB drive and bust it up into partitions all the way up into double-letters, keep in mind that the BIOS may not like big hard drives. My first computer, with a Biostar M5ATB board with BIOS version MI BIOS 2A5KIB09C-00 has a stroke if I connect anything larger than 20GB.

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Reply 4 of 12, by Zup

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Is not that easy.

Keep in mind that, although 2 partitions of 1.6 Gb may be legal for DOS, you BIOS can have smaller limits. A limit of 528 My is typical of 486 systems.

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Reply 5 of 12, by Jo22

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Well.. Technically, MS-DOS 5 and 6.x can support up to ~4GB per partition, but..

That requires patching certain system files and
might cause compatibility issues with HDD utilities and other OSes.

So yes, in practice, 2GB per partition are the limit.
Also, MS-DOS 5/6 have got trouble with HDD geometry that goes past 8GB.

That's the same limit that the third-party FastDisk (aka 32BDFA) drivers for Windows 3. 1x have got.
But here, the BIOS plays a smaller role. These drivers may to query drive geometry directly from the HDD.
So a fake HDD geometry cannot be set up in BIOS Setup in order to limit capacity.

Edit: If you encounter trouble, you may also give MS-DOS 7 a try (for testing purposes).
It is LBA aware, supports 2TB max, 4GB files and has a much more sophisticated bootloader.

Its bootloader, for example, can find system files that are located in various locations,
including sub directories.

By contrast, in DOS 5/6, they must always be located at a fixed location.
That may cause issues, if, say, a disk defragmenter of another OS was at work.

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Reply 6 of 12, by Caluser2000

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Jo22 wrote on 2021-06-15, 03:41:

Well.. Technically, MS-DOS 5 and 6.x can support up to ~4GB per partition, but..

No they can't. NT based windows can though.

Where in the Flying Spaghetti Monsters name do you get this stuff from?

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Reply 7 of 12, by Jo22

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Caluser2000 wrote on 2021-06-15, 04:20:
Jo22 wrote on 2021-06-15, 03:41:

Well.. Technically, MS-DOS 5 and 6.x can support up to ~4GB per partition, but..

No they can't. NT based windows can though.

Where in the Flying Spaghetti Monsters name do you get this stuff from?

You're predictable, sir. I had the feeling that you're lurking around.

There's a patch for MS-DOS 5 that breaks the 1024 cylinder limit.
It depends on the BIOS being honest/compatible (12-Bit cylinder numbers via int13h).

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Reply 8 of 12, by Caluser2000

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So there's a patch blahblah.

Just kidding really. That is cool. So you create the partiition using the default fdisk?

No it doesn't according to the docs. Since came out in 1991 I'm surprised it did go nuclear. Mind you ide drives were quite small back then. In the 40-around 150meg range. A lot orf that space be wasted tough do to the way fat16 operates.

Even the OS/2 installation guide recommends using fat16 for smaller drives

Last edited by Caluser2000 on 2021-06-15, 05:25. Edited 2 times in total.

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Apparently 32-bit is dead and nobody likes P4s.
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Reply 9 of 12, by Jo22

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Caluser2000 wrote on 2021-06-15, 04:50:

So there's a patch blahblah.

Just kidding really. That is cool. So you create the partiiton using the default fdisk?

Yes, the patch works with the FDISK of MS-DOS 5.

I tested it a few years ago in Virtual PC 2007.

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In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 10 of 12, by Caluser2000

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Jo22 wrote on 2021-06-15, 05:12:
Caluser2000 wrote on 2021-06-15, 04:50:

So there's a patch blahblah.

Just kidding really. That is cool. So you create the partiiton using the default fdisk?

Yes, the patch works with the FDISK of MS-DOS 5.

I tested it a few years ago in Virtual PC 2007.

Shivers. The last time I used that was on XP Pro not long after that was produced.

There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉

Reply 11 of 12, by debs3759

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Jo22 wrote on 2021-06-15, 04:45:
You're predictable, sir. I had the feeling that you're lurking around. […]
Show full quote
Caluser2000 wrote on 2021-06-15, 04:20:
Jo22 wrote on 2021-06-15, 03:41:

Well.. Technically, MS-DOS 5 and 6.x can support up to ~4GB per partition, but..

No they can't. NT based windows can though.

Where in the Flying Spaghetti Monsters name do you get this stuff from?

You're predictable, sir. I had the feeling that you're lurking around.

There's a patch for MS-DOS 5 that breaks the 1024 cylinder limit.
It depends on the BIOS being honest/compatible (12-Bit cylinder numbers via int13h).

A 3rd party patch making it possible is not the same as the OS technically supporting anything. The OS may recognise larger partitions after they have been patched (same as 2m30 allows the OS to read 3.5" floppies up to 1.78 MB or larger) but without it, DOS can't create or see them.

I've downloaded the patch to look at later. Shame it doesn't include source code 😀

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Reply 12 of 12, by Jo22

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debs3759 wrote on 2021-06-15, 05:54:
Jo22 wrote on 2021-06-15, 04:45:
You're predictable, sir. I had the feeling that you're lurking around. […]
Show full quote
Caluser2000 wrote on 2021-06-15, 04:20:

No they can't. NT based windows can though.

Where in the Flying Spaghetti Monsters name do you get this stuff from?

You're predictable, sir. I had the feeling that you're lurking around.

There's a patch for MS-DOS 5 that breaks the 1024 cylinder limit.
It depends on the BIOS being honest/compatible (12-Bit cylinder numbers via int13h).

A 3rd party patch making it possible is not the same as the OS technically supporting anything. The OS may recognise larger partitions after they have been patched (same as 2m30 allows the OS to read 3.5" floppies up to 1.78 MB or larger) but without it, DOS can't create or see them.

I've downloaded the patch to look at later. Shame it doesn't include source code 😀

Hi! Please take some time later on and read the documentation! 😀

To quote the author "Since DOS is so very close to supporting really large disks anyway,
I found it possible to patch the DOS disk device driver and eliminate the 1024-cylinder maximum."

That patch is more of a "fix" than the usual patch.

It makes DOS retrieve the drive geometry in a slightly different way and
another, optional utility then changes the state of cylinder 1023 (diagnostic cylinder).

It's MS-DOS 5 itself who's happily supporting ~4GB partitions after changing a few bytes.

With a little bit of thinkering, MS-DOS 6.22 could be made to handle this, too.

The "problem" is, that the utilities are from the early 90s and are hard-coded for English MS-DOS 5.0 (not 5.0a).
Or in other words, they don't know DOS 5.0a/6.x. Thus, they don't know the locations that must be changed in the binary files.

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In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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