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Update SCRN_PLOT_your_sound_routine.md

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2liners/the art of 2-liners/SCRN_PLOT_your_sound_routine.md
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@ -258,16 +258,20 @@ Notice that it can be used for all kinds of subroutines .... just be aware that
How does it work ?
### PRINT
First we start from our 14 routine bytes:
```A6 07 A4 06 AD 30 C0 88 D0 FD CA D0 F5 60```
```
A6 07 A4 06 AD 30 C0 88 D0 FD CA D0 F5 60
```
We leave every number as it is, but we replace all the letters with new letters according to this:
A becomes J, B becomes K, C->L, D->M, E->N and F becomes O.
We now have
```J6 07 J4 06 JM 30 L0 88 M0 OM LJ M0 O5 60```
```
J6 07 J4 06 JM 30 L0 88 M0 OM LJ M0 O5 60
```
We now that TEXT page 1 and Lores page 1 share the same memory location, it starts in $400. Also one line of text is represented as 2 lines of lores graphics.
We know that TEXT page 1 and Lores page 1 share the same memory location, it starts in $400. Also one line of text is represented as 2 lines of lores graphics.
We are going to print every low-nibble (4 bits) of each character on line 1 of TEXT (which is line 0 of GR), this means we rearrange all characters in even positions in the string in another string.
```
@ -288,7 +292,7 @@ If you watch closely, you'll notice that the low nibble is already in place in $
We must find a way to leave unchanged the low nibble of each byte in line 1 and use the low nibble of each byte in line 2 as the high nibble of each byte in line 1.
### SCRN, COLOR & PLOT
As you know, SCRN will return the color of a "point" in Lo-res. You also know that one TEXT character is represented as 2 "vertical" points of various colors in lores.
As you know, ``SCRN`` will return the color of a "point" in Lo-res. You also know that one TEXT character is represented as 2 "vertical" points of various colors in lores.
Here's what our two PRINTs look like in GR:
@ -313,6 +317,11 @@ Here's the code:
4 COLOR = SCRN(I,2): REM +15+1 chars = 63 chars we have a value 0-15
5 PLOT I,1: REM +7+1 chars = 71 chars we PLOT it on line 1, actually adding 16*color to the byte in $400+I
6 NEXT : REM +4 chars = 75 chars
100 REM LET'S HEAR SOMETHING
120 FOR I = 0 TO 255
130 POKE 6,I: POKE 7, 10 : CALL 1024
140 NEXT
```
Even with the ``HOME`` statement at first (which is needed but might already be included in your 2-liner), we have 75+4+1 chars = 80 chars