DOS ain't dead

YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) (Announce)

posted by boeckmann, Aachen, Germany, 27.09.2025, 13:12

> It depends on whether you're talking about DOS in general or FreeDOS
> specifically.

It is more about the DOS most likely using the BIOS to access the hard disk. A EDD3 specification draft (you find it under the name d1572r3-EDD3.pdf) states for the non-LBA access functions that "sector sizes shall be exactly 512 bytes". Albeit this is a draft, I never encountered a different sector size (for hard disks!). I am not sure what the situation regarding the extended disk access routines INT13.4x is. At least INT13.48 seems to expose the physical geometry of the disk. The document makes no statement regarding sector size for these functions. So it MIGHT be that these functions work on the physical sector size of the hard disk, but it MIGHT also be that there is a 512-byte emulation involved. For CDs the document clearly states that the sector size is 2048 bytes: "INT 13 Functions 41h-49h shall access the CD or DVD using non-emulated sector LBA’s in the native sector size
of the CD or DVD". Regarding the draft 1572, I was not able to find out whether there was an official release of this document.

So far for the INT13. Might be a different story when using custom DOS device drivers interacting on a more direct way with the hardware. How does your USBDRIVE handle this? Is it able to handle non-512 BPS devices? And if it is, how does it present such kind of device to the operating system?

Complete thread:

• YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - RayeR, 25.09.2025, 16:25 (Announce)
  • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - Laaca, 25.09.2025, 21:23
    • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - mceric, 25.09.2025, 22:27
      • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - Rugxulo, 26.09.2025, 04:57
        • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - mceric, 26.09.2025, 10:05
        • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - RayeR, 26.09.2025, 15:51
  • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - boeckmann, 26.09.2025, 10:53
    • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - ecm, 26.09.2025, 15:23
    • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - bretjohn, 26.09.2025, 23:48
      • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - boeckmann, 27.09.2025, 13:12
  • YSDDT 0.1.2 (DOS Toolkit for Working with Disks & Partitions) - RayeR, 26.09.2025, 15:55