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Added more screenshots 3, 4, 5, 6, 7
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README.md
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README.md
@ -296,6 +296,8 @@ Enter in:
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And we see the correct: `\`
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And we see the correct: `\`
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![Screenshot 3](pics/hgrfont_03.png?raw=true)
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### Half-pixel shift
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### Half-pixel shift
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Fourth, we mentioned above that when we entered in $80 that the Apple didn't display any pixels for this byte. This is because the Apple uses the high-bit as a flag to shift that group of 7 pixels over HALF a pixel. (Yes, half a pixel.) This means the monochrome *effective* resolution is a pseudo 560x192. We can't individually access every 560 pixels, only part of them so it is not a "true" 560 resolution. :-( What this means in practice is that we can use this half-pixel shift / byte to get very smooth slopes for Y, etc. :-)
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Fourth, we mentioned above that when we entered in $80 that the Apple didn't display any pixels for this byte. This is because the Apple uses the high-bit as a flag to shift that group of 7 pixels over HALF a pixel. (Yes, half a pixel.) This means the monochrome *effective* resolution is a pseudo 560x192. We can't individually access every 560 pixels, only part of them so it is not a "true" 560 resolution. :-( What this means in practice is that we can use this half-pixel shift / byte to get very smooth slopes for Y, etc. :-)
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@ -310,16 +312,43 @@ For example this will give us a "sharp" `Y`:
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3700:8
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3700:8
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3B00:8
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3B00:8
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If we change the 2nd and 4th scan line to:
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![Screenshot 4](pics/hgrfont_04.png?raw=true)
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2700:92
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If we change the 2nd and 4th scan line to use this half-pixel shift we can't just set the high bit as we won't get quite the correct image:
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2F00:8C
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We'll get a "smooth" `Y`.
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Enter in:
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2302:22
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2702:A2 ;
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2B02:14
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2F02:88 ;
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3302:8
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3702:8
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3B02:8
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![Screenshot 5](pics/hgrfont_05.png?raw=true)
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We actually _also_ need to moving the left-edge pixel over by 1 so it appears in the correct location when shifted:
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2304:22
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2704:92 ;
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2B04:14
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2F04:8C ;
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3304:8
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3704:8
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3B04:8
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Ah-ha! We've got "smooth" `Y`.
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![Screenshot 6](pics/hgrfont_06.png?raw=true)
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**Note**: The emulators `Virtual ][` and `Apple2js` are *broken* emulators. They do **not** emulate the half-pixel shift of real hardware at all. This is another reason we won't worry about it for now.
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**Note**: The emulators `Virtual ][` and `Apple2js` are *broken* emulators. They do **not** emulate the half-pixel shift of real hardware at all. This is another reason we won't worry about it for now.
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We're going to ignore the half-pixel shift since it is easy to touch up the font data later if we wish:
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We're going to ignore the half-pixel shift since it is easy to touch up the font data later if we wish.
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At the beginning we said to view the HGR screen in monochrome; Notice how the extra colors make the Hi-Res text much harder to read. If you are running on real hardware the Apple Color Composite Monitor had a push-button on the front to toggle the screen between color and monochrome. Now we know why!
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![Screenshot 7](pics/hgrfont_07.png?raw=true)
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## Font Data
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## Font Data
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BIN
pics/hgrfont_03.png
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BIN
pics/hgrfont_03.png
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After Width: | Height: | Size: 350 B |
BIN
pics/hgrfont_04.png
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BIN
pics/hgrfont_04.png
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After Width: | Height: | Size: 365 B |
BIN
pics/hgrfont_05.png
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BIN
pics/hgrfont_05.png
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After Width: | Height: | Size: 385 B |
BIN
pics/hgrfont_06.png
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BIN
pics/hgrfont_06.png
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After Width: | Height: | Size: 402 B |
BIN
pics/hgrfont_07.png
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BIN
pics/hgrfont_07.png
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After Width: | Height: | Size: 516 B |
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