EMM386 and VDS: not quite working

The other day I set out to solve a seemingly simple problem: With a DOS extended application, lock down memory buffers using DPMI and use them for bus-mastering (BusLogic SCSI HBA, though the exact device model isn’t really relevant to the problem).

Now, DPMI does not allow querying the physical address of a memory region, although it does have provisions for mapping a given physical memory area. But that doesn’t help here–mapping physical memory is useful for framebuffers where a device memory needs to be mapped so that an application can access it. In my case, I needed the opposite, allowing a bus-mastering device to use already-allocated system memory.

I think I may have understood some of these words.


  1. 2020-03-01 7:40 pm
    • 2020-03-01 10:58 pm
      • 2020-03-02 4:46 am
      • 2020-03-02 9:56 am
  2. 2020-03-01 10:39 pm
  3. 2020-03-01 10:46 pm
    • 2020-03-02 4:54 am
      • 2020-03-02 8:42 am
  4. 2020-03-02 11:27 am