DOS ain't dead

SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? (Users)

posted by Zyzzle, 20.10.2021, 05:00

Quick question about SEEKEXT: I installed the TSR, (I'm using the Win95 OSR2 "MS-DOS" v. 7.1) thinking it would make existing DOS programs using signed longint filesizes into unsigned longint seeks. As in, it would enable DOS programs to see "negative" file sizes from 2 GiB to 4 GiB-1 as valid sizes. It did not. With the TSR installed, all programs behaved as before. With files > 2 GiB programs report strange error messages (file cannot be opened, or can't seek in file, etc) and do not work with these large files.

Do all the programs need to be recompiled (unlikely or impossible, as source isn't available) in order to work with SEEKEXT to enable longint unsigned seeks? Archivers like pkzip, RAR, or ACE only support creation of 2 GB archives in "pure" DOS.

Believe we had a discussion almost a decade ago on longseek and unsigned 32-bit and 64-bit file sizes in DOS. I know implementing 64-bit sized seeks would be much more involved than enabling unsigned (4 GiB-1) 32-bit fileseeks.

Is it a DOS limitation, or a program limitation? The only program I've found which "seems" to creat filesizes > 2 GiB is the DOS compilation of 7zip. It creates such files, reads them, but is the only such DOS program I've found that will. It uses CWSDPMI as the extender.

The Mplayer DOS port will not read large movie files from between 2 GiB and 4 GiB, failing to open them. Again, in "ms-dos" 7.1

Complete thread:

• SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - Zyzzle, 20.10.2021, 05:00 (Users)
  • SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - Rugxulo, 20.10.2021, 11:10
    • SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - Zyzzle, 20.10.2021, 14:37
      • SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - KormaX, 25.11.2021, 17:42
  • SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - ecm, 20.10.2021, 12:50
    • SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - Zyzzle, 20.10.2021, 14:51
      • SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - Oso2k, 22.10.2021, 00:39
        • SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - Zyzzle, 22.10.2021, 02:45
    • SEEKEXT and enabling unsigned 32-bit DOS int 0x21 fileseeks? - KormaX, 26.11.2021, 10:31