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Having 2x 2gb partition in dos 6.22

Posted: Tue Aug 22, 2023 6:44 am
by Ratburger
Hey all

I recently purchased an 'Advantage 7409' 166MMX, it had a compact flash drive already installed and I saw this as a bonus as its a hell of a lot easier to copy things from my modern machine with a simple memory card reader onto it.
Anyways, the Flash card installed is 4gb and I noticed that only 2gb of it was being used (Which I understand because DOS can only allocate a certain amount of space at a time), I did the whole disk management through windows 10 and allocated the unused space to a separate drive letter (J: in this case) and formatted it to a FAT file system.

I copied a few test files on it and put it back into the 166mmx running pure DOS 6.22 but the new partition is not showing up, only the original C:

I thought it might be something to do with not being set up in the BIOS and messed around there but its not showing up as an option as a slave.

Any tips on how I can get DOS 6.22 to recognise this drive?

Having 2x 2gb partition in dos 6.22

Posted: Tue Aug 22, 2023 1:41 pm
by MrFlibble
I suggest you ask this in the VOGONS forums.

Having 2x 2gb partition in dos 6.22

Posted: Tue Aug 22, 2023 5:31 pm
by Rwolf
DOS 6.22 natively only understands FAT16, and Windows 10 only creates FAT32 as standard.
To either create a FAT16 on Win10, or access a FAT32 partition from earlier than DOS 7.10, you need to use some 3rd-party software.

There are several ways to do this with various 3rd party partitioning software. (probably somone at Vogons can point you to the best one)
Some examples below that I just found through google, though I have not had the need to use any of them myself:

https://aesmit.org/2020/05/24/format-sd ... indows-10/

https://forum.vcfed.org/index.php?threa ... -22.34304/

Having 2x 2gb partition in dos 6.22

Posted: Wed Aug 23, 2023 6:13 am
by Ratburger
Thanks for the replies guys

I managed to figure it out myself in the end, it was not actually too difficult as I first thought.

As Rwolf pointed out, windows will only format a partition to FAT32, so DOS just sees it as a non DOS partition...even though it can see it and even recognise how much space its taking.

The simple solution - put the memory card in the DOS machine in question and simply run 'Fdisk'

after doing that delete the non-DOS partition, then create an extended DOS partition with the space that will now be available, it will assign a drive letter to this then it will simply restart and all you have to type is (in my case) Format D:
The once missing space is now ready to use.

Having 2x 2gb partition in dos 6.22

Posted: Wed Aug 23, 2023 10:35 am
by Rwolf
Good job!