DOS ain't dead

EMS64 - EMS 4.0 simulator (Announce)

posted by CandyMan, 12.10.2018, 19:18
(edited by CandyMan on 12.10.2018, 22:34)

> Hi, I tried EMS64 and ramdisk on my system with 4GB RAM but I can make only
> ~500MB RAMDISK. If I requested bigger size it failed that not enough
> memory. I loaded the driver via devload under MSDOS 7.1 (devload EMS64.EXE,
> devload SRDEMS.SYS). Does it mean that EMS64 can use really only memory
> beyond 4GB boundary and cannot use memory below? I don't have more RAM so I
> cannot try. In my case BIOS probably remapped some RAM that would be
> overlapped by MMIO beyond 4GB...
The driver this way was constructed in order to use only a memory unavailable to DOS. if you want to use the memory below 4GB use other driver. To a maximum it can be 1GB (since can be maximum 0xFFFF of pages every for 16KB)

> Could you be a bit more specific as to how the driver works. You mention
> "unreal mode", but also "paging tables" in XMS-memory. How does both fit
> together?
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.

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