DOS ain't dead

fix (Developers)

posted by Ninho , 29.05.2011, 14:36

Just a quick passing by to announce I /fixed/ my low memory loading scheme using a bit of stolen free time. It should now be fully correct and TSR resistent, thanks in large part to CM's thought provoking comments. This is achieved without the need to first relocate the installer to the top of low memory.

Main good news :

- never execute from freed memory (duh!)

- freeing/splitting of mem blocks done by direct MCB access, protected
by CLI. (No unsafe int 21 4A nor 49)

- allocation of the final block for TSR placement is done by DOS 21/48, rather than duplicating its function in my code, still inside the section protected by CLI.
It doesn't matter that int 21 will internally do STI, since interrupting TSRs will be prepared to recognise when they were invoked in DOS (having hooked int 21 presumably) and behave accordingly. This is unlike my previous idea ("fake" INDOS while not actually in DOS, which was feeble and indeed unnecessary).

As soon as I've more free time I'll pack and upload an updated testing pack.

See you all

---
Ninho

Complete thread:

• keyb: new! memory scheme, easy TEST - Ninho, 22.05.2011, 19:10 (Developers)
  • boring - ecm, 22.05.2011, 23:58
    • boring - Ninho, 23.05.2011, 01:20
      • not that boring after all (nt) - ecm, 23.05.2011, 13:27
  • review - ecm, 23.05.2011, 13:18
    • review - Ninho, 23.05.2011, 23:10
      • review - ecm, 24.05.2011, 00:45
        • review - Ninho, 24.05.2011, 12:50
          • review - ecm, 24.05.2011, 15:20
            • of TSR powers & limits - Ninho, 25.05.2011, 11:24
              • Swap! - ecm, 25.05.2011, 14:13
                • of TSR powers & limits - Ninho, 25.05.2011, 15:14
    • fix - Ninho, 29.05.2011, 14:36
      • opinion - ecm, 29.05.2011, 14:49
        • opinion - Ninho, 29.05.2011, 16:36
          • evaluation - ecm, 29.05.2011, 17:26
            • evaluation - Ninho, 29.05.2011, 21:00
              • hardly a 100% solution - ecm, 29.05.2011, 22:17
                • hardly a 100% solution - Ninho, 30.05.2011, 19:26
                  • hardly a 100% solution - ecm, 30.05.2011, 19:33
                    • hardly a 100% solution - Ninho, 30.05.2011, 21:14
                      • hardly a 100% solution - ecm, 30.05.2011, 21:20
                        • hardly a 100% solution - Ninho, 30.05.2011, 23:50
                          • allocation no higher than the PSP - ecm, 30.05.2011, 23:56
                            • allocation no higher than the PSP - Ninho, 01.06.2011, 18:56
                              • allocation no higher than the PSP - ecm, 01.06.2011, 19:10
          • opinion - Ninho, 30.05.2011, 19:04
            • sti - ecm, 30.05.2011, 19:26