DOS ain't dead - DOS specifications ("standards")

DOS specifications ("standards") - 33-bit LBA support (Developers)

posted by ecm , Düsseldorf, Germany, 23.11.2020, 10:01

> > (For a hack, we could try to support "33 bit LBA" schemes, ie the 32-bit
> > fields for start and length are kept, but it is valid for start and
> length
> > to *both* be up to FFFF_FFFFh, so (with 512 B/s) a 2 TiB - 512 B FAT32
> > partition may start at sector FFFF_FFFFh. That is, allowing to use nearly
> 4
> > TiB of hard disk space. I'm considering adding that to my early loader
> > (iniload), debugger, and kernel. Most difficult would be the boot sector
> > loaders due to space being at a premium there.)
>
> That is a reasonable stopgap solution. In fact, it might even be supported
> already by some systems, depending on whether they truncate the LBA numbers
> to 32 bits.

I added 33-bit LBA support to my lDOS boot loaders and lDebug. It was actually easier to do than I expected. The usual fields all hold a sector-in-partition, partition start, or partition length (but not sector-in-unit or partition end). So the sector read/write functions which add the sector-in-partition to the partition start are the only places which need to be patched for 33-bit LBA support.

---
l

Post reply

Complete thread:

DOS specifications ("standards") - awik, 18.11.2020, 16:57 (Developers)
- DOS specifications ("standards") - awik, 18.11.2020, 18:48
- DOS specifications ("standards") - RayeR, 18.11.2020, 20:07
  - DOS specifications ("standards") - awik, 19.11.2020, 13:32
- DOS specifications ("standards") - glennmcc, 18.11.2020, 20:22
  - DOS specifications ("standards") - awik, 19.11.2020, 13:44
- DOS specifications ("standards") - Zyzzle, 19.11.2020, 02:23
  - DOS specifications ("standards") - awik, 19.11.2020, 14:02
    - DOS specifications ("standards") - RayeR, 19.11.2020, 19:11
- DOS specifications ("standards") - Laaca, 19.11.2020, 11:27
  - DOS specifications ("standards") - awik, 19.11.2020, 15:03
  - DOS specifications ("standards") - RayeR, 20.11.2020, 02:04
- DOS specifications ("standards") - tkchia, 19.11.2020, 14:12
  - DOS specifications ("standards") - awik, 19.11.2020, 15:11
  - DOS specifications ("standards") - RayeR, 19.11.2020, 19:06
- DOS specifications ("standards") - ecm, 20.11.2020, 16:08
  - DOS specifications ("standards") - awik, 21.11.2020, 16:43
    - DOS specifications ("standards") - tkchia, 21.11.2020, 17:37
      - DOS specifications ("standards") - awik, 21.11.2020, 18:58
        DOS specifications ("standards") - tom, 22.11.2020, 14:58
    - DOS specifications ("standards") - marcov, 22.11.2020, 22:35
      - DOS specifications ("standards") - RayeR, 23.11.2020, 05:49
    - DOS specifications ("standards") - 33-bit LBA support - ecm, 23.11.2020, 10:01
  - DOS specifications ("standards") - ecm, 25.12.2020, 21:27
- Hosting/Sharing - rr, 23.11.2020, 21:19
- DOS specifications ("standards") - Ro2003, 13.01.2024, 09:06
  - DOS specifications ("standards") - awik, 16.01.2024, 11:28
    - DOS specifications ("standards") - jadoxa, 17.01.2024, 02:15
      - DOS specifications ("standards") - Rugxulo, 17.01.2024, 03:40