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Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem (Users)

posted by Japheth , Germany (South), 10.04.2013, 08:47

Ok, the problem is that the himems and jemm stop scanning the int 15h ax=e820h blocks once an available block of extended memory has been found.

addr 000000000, size 00009ec00, type 1 (available)
addr 00009ec00, size 000001400, type 2 (reserved)
addr 0000e0000, size 000020000, type 2 (reserved)
addr 000100000, size 01ff00000, type 1 (available) <--- makes them stop

To skip int 15h-e820h is no option, since int 15h-e801h also reports the size of the first block only.

FD himem/emm386 will behave identically, because the strategy was inherited from those tools.

I vaguely remember that there's a problem with managing multiple blocks. A simple solution might be to scan via e820h until the end and then use the largest block ( within the first 4 GB ). However, this might cause problems with SoundBlaster emulators, since, IIRC, they expect to be within the first physical 16 MB.

---
MS-DOS forever!

Complete thread:

• Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - RayeR, 09.04.2013, 20:31
  • Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - Japheth, 09.04.2013, 20:48
    • Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - RayeR, 09.04.2013, 23:03
      • Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - Japheth, 10.04.2013, 08:47
        • Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - RayeR, 10.04.2013, 10:21
          • Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - Japheth, 10.04.2013, 13:49
            • Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - RayeR, 11.04.2013, 16:23
  • Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - Zyzzle, 10.04.2013, 02:35
    • Gigabyte GA-B75M-D3V quick DOS test, XMS size detect.problem - RayeR, 10.04.2013, 10:25
  • XMGR is supposed to use all memory blocks up to 4 GB - Japheth, 21.04.2013, 09:39
    • XMGR is supposed to use all memory blocks up to 4 GB - RayeR, 22.04.2013, 01:45