DOS ain't dead

phar lap (Developers)

posted by kerravon, Ligao, Free World North, 06.06.2023, 11:13

> > But unfortunately the method of doing huge pointers
> > effectively hardcodes a 4-bit shift into executables.
>
> VC 1.52 uses "external" constants _AHINCR and _AHSHIFT, that work for both
> real-mode and protected-mode ( assuming that the protected-mode OS uses
> "selector tiling" for blocks > 64 kB ).

Thanks for that information. I was surprised to
see that it works in protected mode.

The generated code I showed above didn't use AHINCR
and didn't look like it would work in PM16.

A search found this somewhat unrelated:

http://www.delphigroups.info/2/ae/107069.html

{ AHincr is 8 in Standard and Enhanced mode, $1000 in real mode.
AHshift is 3 in Standard and Enhanced mode, 12 in real mode (2^AHshift=AHincr) }


It will take some time for me to wrap my head around
this to find out whether I can get huge memory model
DOS executables compiled with Visual Studio 1.52, but
linked with a (modified) PDPCLIB to run under a future
PDOS/286 with selectors appropriately lined up.

And hopefully on PM16 on a 386 those executables would
be able to access much more than 16 MiB of memory.

BFN. Paul.

Complete thread:

• phar lap - kerravon, 31.05.2023, 17:57 (Developers)
  • phar lap - jadoxa, 01.06.2023, 02:25
    • phar lap - kerravon, 01.06.2023, 07:40
  • phar lap - Rugxulo, 01.06.2023, 03:03
    • phar lap - kerravon, 01.06.2023, 07:39
  • phar lap - Japheth, 01.06.2023, 14:28
    • phar lap - kerravon, 06.06.2023, 11:13
    • phar lap - kerravon, 25.06.2023, 13:44
  • phar lap - neozeed, 17.06.2023, 10:59
  • phar lap - kerravon, 25.07.2023, 14:11
    • phar lap - Rugxulo, 25.07.2023, 19:29