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Chebucto Regional Softball Club

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  3. tandy put their sound chip on the 1A interrupt?
A forum for discussing and organizing recreational softball and baseball games and leagues in the greater Halifax area.

tandy put their sound chip on the 1A interrupt?

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  • Foone🏳️‍⚧️F Foone🏳️‍⚧️

    so like, midisnd.dat will have 12 entries, and the first 11 are 200-500 bytes each, and then the last is 3k.
    presumably it's each song and then some config info?

    Foone🏳️‍⚧️F This user is from outside of this forum
    Foone🏳️‍⚧️F This user is from outside of this forum
    Foone🏳️‍⚧️
    wrote on last edited by
    #70

    cities.dat is very interesting. There's 30 cities in total, but 491 entries in it!

    So they must be doing something odd there, that doesn't divide equally. Maybe one city-chunk gives IDs of the others?

    Foone🏳️‍⚧️F 1 Reply Last reply
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    • Foone🏳️‍⚧️F Foone🏳️‍⚧️

      cities.dat is very interesting. There's 30 cities in total, but 491 entries in it!

      So they must be doing something odd there, that doesn't divide equally. Maybe one city-chunk gives IDs of the others?

      Foone🏳️‍⚧️F This user is from outside of this forum
      Foone🏳️‍⚧️F This user is from outside of this forum
      Foone🏳️‍⚧️
      wrote on last edited by
      #71

      idea for a test: it's easy to spot which chunk in a city is the image, because it's the biggest. Here's a way to determine if it's looking up by IDs or offsets/indices: swap the IDs of two images

      Foone🏳️‍⚧️F 1 Reply Last reply
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      • Foone🏳️‍⚧️F Foone🏳️‍⚧️

        idea for a test: it's easy to spot which chunk in a city is the image, because it's the biggest. Here's a way to determine if it's looking up by IDs or offsets/indices: swap the IDs of two images

        Foone🏳️‍⚧️F This user is from outside of this forum
        Foone🏳️‍⚧️F This user is from outside of this forum
        Foone🏳️‍⚧️
        wrote on last edited by
        #72

        darn. turns out you can't just renumber the chunks, because they have to be in increasing order.

        so maybe I just need to leave the chunk indexes as is, and instead of moving the entries around, I move where they're pointing?

        Foone🏳️‍⚧️F 1 Reply Last reply
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        • Foone🏳️‍⚧️F Foone🏳️‍⚧️

          darn. turns out you can't just renumber the chunks, because they have to be in increasing order.

          so maybe I just need to leave the chunk indexes as is, and instead of moving the entries around, I move where they're pointing?

          Foone🏳️‍⚧️F This user is from outside of this forum
          Foone🏳️‍⚧️F This user is from outside of this forum
          Foone🏳️‍⚧️
          wrote on last edited by
          #73

          Bingo! I'm in Athens, but I'm seeing the image for Baghdad, and apparently with the Baghdad palette?

          So one of these other chunks must be the palette for a city. Or it selects from a selection of palettes? Maybe they've just got a couple defined.

          Link Preview Image
          Foone🏳️‍⚧️F 1 Reply Last reply
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          • Foone🏳️‍⚧️F Foone🏳️‍⚧️

            Bingo! I'm in Athens, but I'm seeing the image for Baghdad, and apparently with the Baghdad palette?

            So one of these other chunks must be the palette for a city. Or it selects from a selection of palettes? Maybe they've just got a couple defined.

            Link Preview Image
            Foone🏳️‍⚧️F This user is from outside of this forum
            Foone🏳️‍⚧️F This user is from outside of this forum
            Foone🏳️‍⚧️
            wrote on last edited by
            #74

            okay I figured out the cities.dat IDs:

            They're all 1XXYY (in decimal):
            XX is the city number (0-29), YY is the sub-chunk-id.

            So like:
            YY=0: City name
            YY=2: City image.

            They go between 00 and 22, and not all numbers need to be present.

            Foone🏳️‍⚧️F 1 Reply Last reply
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            • Foone🏳️‍⚧️F Foone🏳️‍⚧️

              okay I figured out the cities.dat IDs:

              They're all 1XXYY (in decimal):
              XX is the city number (0-29), YY is the sub-chunk-id.

              So like:
              YY=0: City name
              YY=2: City image.

              They go between 00 and 22, and not all numbers need to be present.

              Foone🏳️‍⚧️F This user is from outside of this forum
              Foone🏳️‍⚧️F This user is from outside of this forum
              Foone🏳️‍⚧️
              wrote on last edited by
              #75

              hmm, reading a buffer and then summing all the values of the bytes in it.

              suspicious behavior.

              Foone🏳️‍⚧️F 1 Reply Last reply
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              • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                hmm, reading a buffer and then summing all the values of the bytes in it.

                suspicious behavior.

                Foone🏳️‍⚧️F This user is from outside of this forum
                Foone🏳️‍⚧️F This user is from outside of this forum
                Foone🏳️‍⚧️
                wrote on last edited by
                #76

                okay I think it has a very simple 1-byte CRC check on the chunks, which are optionally not run.
                I can't make the math work but I'm reasonably sure that's what it is

                Foone🏳️‍⚧️F 1 Reply Last reply
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                • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                  okay I think it has a very simple 1-byte CRC check on the chunks, which are optionally not run.
                  I can't make the math work but I'm reasonably sure that's what it is

                  Foone🏳️‍⚧️F This user is from outside of this forum
                  Foone🏳️‍⚧️F This user is from outside of this forum
                  Foone🏳️‍⚧️
                  wrote on last edited by
                  #77

                  okay they're using a blit that's UI-aware, so it starts the coordinate system at (1,13). Fun!

                  Foone🏳️‍⚧️F 1 Reply Last reply
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                  • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                    okay they're using a blit that's UI-aware, so it starts the coordinate system at (1,13). Fun!

                    Foone🏳️‍⚧️F This user is from outside of this forum
                    Foone🏳️‍⚧️F This user is from outside of this forum
                    Foone🏳️‍⚧️
                    wrote on last edited by
                    #78

                    looking into the blitting code I managed to steal the world map out of RAM

                    Link Preview Image
                    Foone🏳️‍⚧️F 1 Reply Last reply
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                    • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                      looking into the blitting code I managed to steal the world map out of RAM

                      Link Preview Image
                      Foone🏳️‍⚧️F This user is from outside of this forum
                      Foone🏳️‍⚧️F This user is from outside of this forum
                      Foone🏳️‍⚧️
                      wrote on last edited by
                      #79

                      ugh. TODO for my eventual Good DOS Debugger:
                      Instant Video display.
                      I don't know exactly how DOSBox-X is doing it, but while single-stepping the debugger, the display never updates. I can dump the ram at A000:0000 and see what updated, but not on the screen in DOSBox

                      Foone🏳️‍⚧️F 1 Reply Last reply
                      0
                      • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                        ugh. TODO for my eventual Good DOS Debugger:
                        Instant Video display.
                        I don't know exactly how DOSBox-X is doing it, but while single-stepping the debugger, the display never updates. I can dump the ram at A000:0000 and see what updated, but not on the screen in DOSBox

                        Foone🏳️‍⚧️F This user is from outside of this forum
                        Foone🏳️‍⚧️F This user is from outside of this forum
                        Foone🏳️‍⚧️
                        wrote on last edited by
                        #80

                        found a suspicious array, which goes:
                        [
                        (-1,0),
                        (-1,1),
                        (0,1),
                        (1,1),
                        (1,0),
                        (1,-1),
                        (0, -1),
                        (-1,-1),
                        (0,0)
                        ]

                        POP QUIZ: why does the font renderer need this array? how are they being "lazy" with this array?

                        Foone🏳️‍⚧️F 1 Reply Last reply
                        0
                        • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                          found a suspicious array, which goes:
                          [
                          (-1,0),
                          (-1,1),
                          (0,1),
                          (1,1),
                          (1,0),
                          (1,-1),
                          (0, -1),
                          (-1,-1),
                          (0,0)
                          ]

                          POP QUIZ: why does the font renderer need this array? how are they being "lazy" with this array?

                          Foone🏳️‍⚧️F This user is from outside of this forum
                          Foone🏳️‍⚧️F This user is from outside of this forum
                          Foone🏳️‍⚧️
                          wrote on last edited by
                          #81

                          there's also this code in the for-loop that steps through this array:

                          if index==8:
                          color=white
                          else:
                          color=black

                          Foone🏳️‍⚧️F 1 Reply Last reply
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                          • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                            there's also this code in the for-loop that steps through this array:

                            if index==8:
                            color=white
                            else:
                            color=black

                            Foone🏳️‍⚧️F This user is from outside of this forum
                            Foone🏳️‍⚧️F This user is from outside of this forum
                            Foone🏳️‍⚧️
                            wrote on last edited by
                            #82

                            @dividuum got it:

                            they're drawing the font 9 times, offset in each of the 8 directions, and in black. then they draw it in white, with no offset.

                            It's a pixel-outliner! By drawing their pixel font offset in each direction, they get a black outline on their font.

                            Foone🏳️‍⚧️F 1 Reply Last reply
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                            • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                              @dividuum got it:

                              they're drawing the font 9 times, offset in each of the 8 directions, and in black. then they draw it in white, with no offset.

                              It's a pixel-outliner! By drawing their pixel font offset in each direction, they get a black outline on their font.

                              Foone🏳️‍⚧️F This user is from outside of this forum
                              Foone🏳️‍⚧️F This user is from outside of this forum
                              Foone🏳️‍⚧️
                              wrote on last edited by
                              #83

                              The Answer to the DRM questions for Where in the world is Carmen Sandiego? Enhanced (DOS, 1990) are, in no particular order:

                              23
                              Kent
                              dragon
                              calcium
                              1796
                              Warren
                              revenue
                              1792
                              Willard
                              1937
                              Crater
                              Tanzania
                              Hartford
                              Duluth
                              London
                              Gem
                              Silent
                              squeaker

                              Foone🏳️‍⚧️F 1 Reply Last reply
                              0
                              • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                                The Answer to the DRM questions for Where in the world is Carmen Sandiego? Enhanced (DOS, 1990) are, in no particular order:

                                23
                                Kent
                                dragon
                                calcium
                                1796
                                Warren
                                revenue
                                1792
                                Willard
                                1937
                                Crater
                                Tanzania
                                Hartford
                                Duluth
                                London
                                Gem
                                Silent
                                squeaker

                                Foone🏳️‍⚧️F This user is from outside of this forum
                                Foone🏳️‍⚧️F This user is from outside of this forum
                                Foone🏳️‍⚧️
                                wrote on last edited by
                                #84

                                if ((0x80 >> ((byte)local_4 & 7) &
                                (int)(char)*(byte *)((int)((int *)param_1 + 1) + (local_4 >> 3))) != 0) {

                                COULD YOU USE SOME MORE CASTS MAYBE?

                                Foone🏳️‍⚧️F 1 Reply Last reply
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                                • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                                  if ((0x80 >> ((byte)local_4 & 7) &
                                  (int)(char)*(byte *)((int)((int *)param_1 + 1) + (local_4 >> 3))) != 0) {

                                  COULD YOU USE SOME MORE CASTS MAYBE?

                                  Foone🏳️‍⚧️F This user is from outside of this forum
                                  Foone🏳️‍⚧️F This user is from outside of this forum
                                  Foone🏳️‍⚧️
                                  wrote on last edited by
                                  #85

                                  oh it's because ghidra's near/far pointer support is shit.

                                  I had param2 defined as a byte*32 and it was casting it to a byte* before using it

                                  Foone🏳️‍⚧️F 1 Reply Last reply
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                                  • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                                    oh it's because ghidra's near/far pointer support is shit.

                                    I had param2 defined as a byte*32 and it was casting it to a byte* before using it

                                    Foone🏳️‍⚧️F This user is from outside of this forum
                                    Foone🏳️‍⚧️F This user is from outside of this forum
                                    Foone🏳️‍⚧️
                                    wrote on last edited by
                                    #86

                                    if I define it as byte* and let the calling convention implicitly define it as 32bit, it doesn't do the cast

                                    Foone🏳️‍⚧️F 1 Reply Last reply
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                                    • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                                      if I define it as byte* and let the calling convention implicitly define it as 32bit, it doesn't do the cast

                                      Foone🏳️‍⚧️F This user is from outside of this forum
                                      Foone🏳️‍⚧️F This user is from outside of this forum
                                      Foone🏳️‍⚧️
                                      wrote on last edited by
                                      #87

                                      well I found the decompression method.

                                      as always, I hate it. decompression routines are probably my least favorite thing to reverse engineer

                                      Foone🏳️‍⚧️F 1 Reply Last reply
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                                      • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                                        well I found the decompression method.

                                        as always, I hate it. decompression routines are probably my least favorite thing to reverse engineer

                                        Foone🏳️‍⚧️F This user is from outside of this forum
                                        Foone🏳️‍⚧️F This user is from outside of this forum
                                        Foone🏳️‍⚧️
                                        wrote on last edited by
                                        #88

                                        I think this compression is specifically designed for ASCII text, which is annoying because they've also got compressed images... which probably use a DIFFERENT COMPRESSION!

                                        Foone🏳️‍⚧️F 1 Reply Last reply
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                                        • Foone🏳️‍⚧️F Foone🏳️‍⚧️

                                          I think this compression is specifically designed for ASCII text, which is annoying because they've also got compressed images... which probably use a DIFFERENT COMPRESSION!

                                          Foone🏳️‍⚧️F This user is from outside of this forum
                                          Foone🏳️‍⚧️F This user is from outside of this forum
                                          Foone🏳️‍⚧️
                                          wrote on last edited by
                                          #89

                                          it looks like this chunk has length 256, which means 253 usable bytes, and it expands to 374 bytes.

                                          Not the greatest compression. a little better than just doing 6-bit ASCII.

                                          Foone🏳️‍⚧️F 1 Reply Last reply
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