DOS ain't dead

OS/2 extender (Developers)

posted by kerravon , Ligao, Free World North, 12.09.2025, 16:55

> Have you seen EMS64
> - EMS 4.0 simulator on FASM's forum?

I just took a look. Doesn't look like a DOS extender to me, which is what I'm after. It will most likely be an x64 DOS or OS/2 extender to run Win64 executables.

BTW, I was scratching my head to try to find out what an issue might be - and I had a thought that maybe the thinking is that OS/2 will fail to execute the code that I need to switch to LM64 because it isn't paged in.

In which case, there are a couple of solutions.

One would be to access one byte in each 4k page of the code I wish to execute and use to make sure it is paged in at the time I go to execute it.

Another would be to allocate 8K of memory from OS/2 to ensure that I have a full 4k page, and then place code there that is designed to switch to and from LM64 as well as provide 512 bytes of memory (so rwx) that can be used as a buffer for when the Win64 program wishes to write to a file.

PDOS/386 alread does everything 512 bytes at a time, switching from PM32 to RM16 to read/write a sector at a time.

Isn't an issue in practice. The biggest task I do is do optimized gcc 3.2.3 C compiles under an S/370 mainframe emulator and the bottleneck is all in the CPU (actually, memory access I believe - but it shows up as CPU). Mode switching and writing sectors to an SSD isn't an issue.

Complete thread:

• OS/2 extender - kerravon, 10.09.2025, 21:05 (Developers)
  • OS/2 extender - Rugxulo, 10.09.2025, 21:30
  • OS/2 extender - Ringding, 11.09.2025, 17:44
    • OS/2 extender - kerravon, 11.09.2025, 17:57
      • OS/2 extender - Ringding, 11.09.2025, 20:41
        • OS/2 extender - kerravon, 12.09.2025, 00:08
          • OS/2 extender - Rugxulo, 12.09.2025, 04:07
            • OS/2 extender - kerravon, 12.09.2025, 16:55
          • OS/2 extender - Ringding, 12.09.2025, 17:20
            • OS/2 extender - kerravon, 12.09.2025, 18:03