DOS ain't dead

DarkDebugger (Users)

posted by Japheth , Germany (South), 23.06.2022, 17:05

I'm currently checking an old graphics app in a vga 16-color mode. This app used to work, but on newer cards the output is "scattered" ( or perhaps it's not the "newer cards", but the "newer cpus").

As it has turned out, I had to make this change:


;    mov     al,ah
;    xchg    al,[bx]
    mov al,[bx]
    mov [bx],ah


Using XCHG with memory operands is usually a bad idea, but even more so in the vga "plane" modes. Better do a clean read to fill the "latch" register, then the write. I guess it's also "significantly" faster.

---
MS-DOS forever!

Complete thread:

• JEMM386 v5.81 hangs - CandyMan, 03.05.2022, 23:23 (Users)
  • JEMM386 v5.81 hangs - Japheth, 04.05.2022, 03:18
    • JEMM386 v5.81 hangs - CandyMan, 04.05.2022, 09:30
      • JEMM386 v5.81 hangs - Japheth, 04.05.2022, 10:34
        • JEMM386 v5.81 hangs - CandyMan, 04.05.2022, 16:02
          • JEMM386 v5.81 hangs - Japheth, 05.05.2022, 08:11
          • JEMM386 v5.81 hangs - RayeR, 18.05.2022, 22:48
            • JEMM386 v5.81 hangs - CandyMan, 23.05.2022, 17:43
              • DarkDebugger - RayeR, 25.05.2022, 17:59
                • JEMM386 v5.81 hangs - CandyMan, 25.05.2022, 18:55
                  • DarkDebugger - RayeR, 26.05.2022, 03:59
                    • DarkDebugger - CandyMan, 26.05.2022, 19:41
                      • DarkDebugger - RayeR, 11.06.2022, 03:26
                        • DarkDebugger - CandyMan, 12.06.2022, 19:00
                          • DarkDebugger - RayeR, 17.06.2022, 19:09
                            • DarkDebugger - CandyMan, 18.06.2022, 22:41
                              • DarkDebugger - RayeR, 23.06.2022, 00:07
                                • DarkDebugger - CandyMan, 23.06.2022, 11:27
                                  • DarkDebugger - Japheth, 23.06.2022, 17:05
        • JEMM386 v5.81 hangs - tkchia, 04.05.2022, 23:11
          • JEMM386 v5.81 hangs - Japheth, 05.05.2022, 08:42
            • JEMM386 v5.81 hangs - tkchia, 05.05.2022, 11:56
  • JEMM386 v5.81 hangs - CandyMan, 25.05.2022, 18:59
    • JEMM386 v5.81 hangs - Japheth, 27.05.2022, 17:10
      • JEMM386 v5.81 hangs - CandyMan, 28.05.2022, 19:27
        • JEMM386 v5.81 hangs - Japheth, 29.05.2022, 04:46