DOS ain't dead

comment on flushing predecode queue (pre-Pentium) (DOSX)

posted by Ninho , 23.04.2008, 20:22

> This might be true, but I don't own a working 80386 system and cannot
> change working code just because theory suggests that it may have troubles
> on a 80386. I need facts. (Just in case, your second name isn't Eric?)

Hey! This is not a theory, it's one of the few things consistently and correctly documented in Intel manuals; and it's not just the 386, the 486 as well needs it - I used to have the printed Intel manual. Mind you, I'm not sure whether it even is not still officially recommended, or required, for some later processors (not just Intel's). When doing a mode switch, in general you'll need both : a near jump (to flush the queue) and a far transfer (to fully load CS and its attributes). Of course, in this particular piece of code, you don't want the far jump, since you're only setting up "big real" mode, but you need the short jmp.

I'm really surprised you are not aware of this point, considering the depth of your experience.

And no, I'm not an Eric ;=)

Regards...

---
Ninho

Complete thread:

• comment on flushing predecode queue (pre-Pentium) - Ninho, 23.04.2008, 10:06 (DOSX)
  • comment on flushing predecode queue (pre-Pentium) - Japheth, 23.04.2008, 19:54
    • comment on flushing predecode queue (pre-Pentium) - Ninho, 23.04.2008, 20:22
      • comment on flushing predecode queue (pre-Pentium) - Japheth, 23.04.2008, 21:04
        • comment on flushing predecode queue (pre-Pentium) - Ninho, 23.04.2008, 23:32
          • comment on flushing predecode queue (pre-Pentium) - Rugxulo, 24.04.2008, 19:18
            • comment on flushing predecode queue (pre-Pentium) - RayeR, 24.04.2008, 22:34
              • comment on flushing predecode queue (pre-Pentium) - Ninho, 25.04.2008, 08:11
                • comment on flushing predecode queue (pre-Pentium) - Japheth, 25.04.2008, 08:58
                  • comment on flushing predecode queue (pre-Pentium) - Ninho, 25.04.2008, 09:23
                    • comment on flushing predecode queue (pre-Pentium) - Japheth, 25.04.2008, 09:31
                      • comment on flushing predecode queue (pre-Pentium) - Ninho, 25.04.2008, 09:52
                        • comment on flushing predecode queue (pre-Pentium) - rr, 25.04.2008, 10:00
                          • comment on flushing predecode queue (pre-Pentium) - Ninho, 25.04.2008, 10:09
                          • comment on flushing predecode queue (pre-Pentium) - Steve, 25.04.2008, 11:05
                        • comment on flushing predecode queue (pre-Pentium) - Steve, 25.04.2008, 11:04
                          • comment on flushing predecode queue (pre-Pentium) - rr, 25.04.2008, 11:11
                            • comment on flushing predecode queue (pre-Pentium) - Japheth, 25.04.2008, 11:18
                              • comment on flushing predecode queue (pre-Pentium) - rr, 25.04.2008, 11:21
                                • comment on flushing predecode queue (pre-Pentium) - Japheth, 25.04.2008, 11:24
                                  • comment on flushing predecode queue (pre-Pentium) - rr, 25.04.2008, 11:41
                                    • comment on flushing predecode queue (pre-Pentium) - Japheth, 25.04.2008, 13:57
                                      • comment on flushing predecode queue (pre-Pentium) - rr, 25.04.2008, 14:34
                            • comment on flushing predecode queue (pre-Pentium) - Ninho, 25.04.2008, 11:34
                              • comment on flushing predecode queue (pre-Pentium) - Steve, 25.04.2008, 11:55
                                • comment on flushing predecode queue (pre-Pentium) - Ninho, 25.04.2008, 13:09
                                  • comment on flushing predecode queue (pre-Pentium) - Steve, 25.04.2008, 14:18
                      • comment on flushing predecode queue (pre-Pentium) - Rugxulo, 25.04.2008, 20:55
                • comment on flushing predecode queue (pre-Pentium) - RayeR, 26.04.2008, 00:54
                  • comment on flushing predecode queue (pre-Pentium) - Japheth, 26.04.2008, 09:49
                    • comment on flushing predecode queue (pre-Pentium) - Ninho, 26.04.2008, 10:29
                      • comment on flushing predecode queue (pre-Pentium) - Rugxulo, 26.04.2008, 20:57
                    • comment on flushing predecode queue (pre-Pentium) - RayeR, 27.04.2008, 01:52
                      • comment on flushing predecode queue (pre-Pentium) - Rugxulo, 27.04.2008, 05:36
                        • comment on flushing predecode queue (pre-Pentium) - RayeR, 27.04.2008, 13:20
                          • comment on flushing predecode queue (pre-Pentium) - Rugxulo, 27.04.2008, 20:20
                            • comment on flushing predecode queue (pre-Pentium) - flox, 27.04.2008, 22:08
                              • comment on flushing predecode queue (pre-Pentium) - Steve, 28.04.2008, 02:44
                        • comment on flushing predecode queue (pre-Pentium) - marcov, 27.04.2008, 15:46
                      • comment on flushing predecode queue (pre-Pentium) - Ninho, 27.04.2008, 10:10
                        • comment on flushing predecode queue (pre-Pentium) - Japheth, 28.04.2008, 11:50
                    • comment on flushing predecode queue (pre-Pentium) - tom, 27.04.2008, 14:46
                    • HIMEMX bug - DOS386, 01.05.2008, 05:48
                      • HIMEMX bug - Japheth, 01.05.2008, 09:20