DOS ain't dead

For Rayer - shared resources between DOS and WinXP (Announce)

posted by RayeR , CZ, 11.07.2008, 02:53
(edited by RayeR on 11.07.2008, 03:09)

I tried a small experiment in DJGPP.
I made a simple program which dumps CS, DS, SS decriptors and show its bases. I run it under NTVDM and the result was:

CS: 1A7h, base = 029E0000h, limit = 9FFFFh, granularity = 1B
DS: 1AFh, base = 029E0000h, limit = 9FFFFh, granularity = 1B
SS: 1AFh, base = 029E0000h, limit = 9FFFFh, granularity = 1B
DOS_DS: 1AFh, base = 00000000h, limit = 0010Fh, granularity = 4096B
MSGPTR: 118E0h

I have placed magic string at offset 118E0.
Parallel with this program I launched Read & Write utility and look at physical
assress equal to base+offset but no magic string there. I searched through phys memory and found it much higher somewhere over 50000000, 60000000 and more in some instances. Hm is it messed up due to paging? Normally I would expect that segment descriptor base address is physical address... So seems a VDD is only possible way (except that damn ramdisk :)

EDIT:
Grrr, I ran muliple instances of my program and all has reported 029E0000h same base, it's impossible to be physical address.

EDIT2:
Under Win98 each instance of program got unique base addres but this is also not true physical address

CS: A7h, base = 84E9F000h, limit = 9FFFFh, granularity = 1B
DS: AFh, base = 84E9F000h, limit = 9FFFFh, granularity = 1B
SS: AFh, base = 84E9F000h, limit = 9FFFFh, granularity = 1B
DOS_DS: AFh, base = 00000000h, limit = 0010Fh, granularity = 4096B
MSGPTR: 118E0h

---
DOS gives me freedom to unlimited HW access.

Complete thread:

• For Rayer - shared resources between DOS and WinXP - Laaca, 05.07.2008, 10:08 (Announce)
  • For Rayer - shared resources between DOS and WinXP - Japheth, 05.07.2008, 11:27
    • For Rayer - shared resources between DOS and WinXP - RayeR, 06.07.2008, 13:26
      • For Rayer - shared resources between DOS and WinXP - Japheth, 07.07.2008, 09:19
        • For Rayer - shared resources between DOS and WinXP - RayeR, 08.07.2008, 14:02
          • For Rayer - shared resources between DOS and WinXP - Japheth, 08.07.2008, 17:08
            • For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 02:53
              • For Rayer - shared resources between DOS and WinXP - Japheth, 11.07.2008, 09:30
                • For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 11:18
                  • For Rayer - shared resources between DOS and WinXP - Japheth, 11.07.2008, 11:38
                    • For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 14:12
                      • For Rayer - shared resources between DOS and WinXP - Japheth, 11.07.2008, 20:39
                        • For Rayer - shared resources between DOS and WinXP - RayeR, 16.07.2008, 15:51
                          • For Rayer - shared resources between DOS and WinXP - Japheth, 17.07.2008, 08:20
                            • For Rayer - shared resources between DOS and WinXP - RayeR, 17.07.2008, 12:25
                              • For Rayer - shared resources between DOS and WinXP - Japheth, 17.07.2008, 13:38
                                • For Rayer - shared resources between DOS and WinXP - RayeR, 17.07.2008, 14:05
                                  • For Rayer - shared resources between DOS and WinXP - Rugxulo, 17.07.2008, 14:35
                                    • For Rayer - shared resources between DOS and WinXP - RayeR, 17.07.2008, 18:55
                                      • For Rayer - shared resources between DOS and WinXP - Rugxulo, 18.07.2008, 13:50
                                        • For Rayer - shared resources between DOS and WinXP - RayeR, 22.07.2008, 10:24
                                          • For Rayer - shared resources between DOS and WinXP - Rugxulo, 23.07.2008, 00:51
                                            • For Rayer - shared resources between DOS and WinXP - RayeR, 23.07.2008, 16:56
                                              • For Rayer - shared resources between DOS and WinXP - Rugxulo, 24.07.2008, 07:06
            • For Rayer - shared resources between DOS and WinXP - Rugxulo, 23.07.2008, 01:00
  • For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 23:04
    • For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 23:19
  • For Rayer - shared resources between DOS and WinXP - ho1459, 13.07.2008, 08:40