DOS ain't dead

EMS64 - EMS 4.0 simulator (Announce)

posted by Japheth , Germany (South), 13.10.2018, 14:15

> The driver temporarily is switching over to the long mode without
> interrupts in order to copy the memory to/from the page frame. The paging
> tables are being initiated after the run a driver (using unreal mode) only
> once and can be in an extended memory.

I see. So unreal mode is just used to fill the page tables.

During my (brief) tests I noticed:

1. Uninstall works, but the driver uninstalles even if there is still EMS memory allocated. This shouldn't be.

2. Page frame address is just paragraph aligned ( according to docs "should" be 16 kB aligned ). Some programs won't run in such an environment.

3. The driver assumes that it is the only consumer of RAM beyond the 4 GB boundary. That's a bit reckless, for example there's CWSDPMI v7, which may also use this RAM ( via PSE ). The driver should intercept Int 15, ax=e820h and ensure that the memory it used is no longer reported as "available".

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MS-DOS forever!

Complete thread:

• EMS64 - EMS 4.0 simulator - CandyMan, 06.10.2018, 18:24 (Announce)
  • EMS64 - EMS 4.0 simulator - RayeR, 07.10.2018, 23:09
  • EMS64 - EMS 4.0 simulator - RayeR, 10.10.2018, 23:12
  • EMS64 - EMS 4.0 simulator - Japheth, 11.10.2018, 13:59
    • EMS64 - EMS 4.0 simulator - CandyMan, 12.10.2018, 19:18
      • EMS64 - EMS 4.0 simulator - Japheth, 13.10.2018, 14:15
        • EMS64 - EMS 4.0 simulator - CandyMan, 13.10.2018, 22:35