DOS ain't dead

Device drivers: Changing the attribute word at install time? (Developers)

posted by mbbrutman , Washington, USA, 02.10.2023, 23:47

I'm writing my first device driver and I'd like it to run on DOS 2.1 and up without providing different versions. (I'm going to ignore DOS 4.x here.)

All of the documentation that I'm reading implies that the attribute word of the device header is read only. Except for the book "Writing MS-DOS Device Drivers" by Robert S. Lai, which talks about an advanced method where the install routine queries DOS and then modifies the attribute word based on what is needed.

For me I'm interested in bit 1 which indicates if 32 bit block addressing is available. This makes sense for DOS 5 but not for older versions of DOS.

Is modifying the attribute word a legitimate way to handle this? Do you know of any device drivers that do this? I suppose it works but that assumes that DOS evaluates it after the initialization routine, and I can't find anything that says when the attribute word is evaluated.


-Mike

Complete thread:

• Device drivers: Changing the attribute word at install time? - mbbrutman, 02.10.2023, 23:47 (Developers)
  • Device drivers: Changing the attribute word at install time? - glennmcc, 03.10.2023, 03:43
  • Device drivers: Changing the attribute word at install time? - mbbrutman, 03.10.2023, 20:21
    • Device drivers: Changing the attribute word at install time? - ecm, 03.10.2023, 20:56
      • Device drivers: Changing the attribute word at install time? - mbbrutman, 03.10.2023, 21:26
        • Device drivers: Changing the attribute word at install time? - tkchia, 03.10.2023, 21:32
          • Device drivers: Changing the attribute word at install time? - mbbrutman, 03.10.2023, 22:48
          • Device drivers: Changing the attribute word at install time? - tom, 04.10.2023, 23:43
  • Device drivers: Changing the attribute word at install time? - tkchia, 03.10.2023, 21:28
    • Device drivers: Changing the attribute word at install time? - mbbrutman, 03.10.2023, 22:51
      • Device drivers: Changing the attribute word at install time? - bretjohn, 06.10.2023, 21:35
        • Device drivers: Changing the attribute word at install time? - mbbrutman, 07.10.2023, 20:42
          • Device drivers: Changing the attribute word at install time? - bretjohn, 09.10.2023, 19:17
            • Device drivers: Changing the attribute word at install time? - mbbrutman, 02.11.2023, 19:39
  • Device drivers: Changing the attribute word at install time? - Rugxulo, 23.11.2023, 22:15