Add getting-started to part 2

src/SUMMARY.md

@@ -23,6 +23,7 @@
 
 # Part Ⅱ — Our first game
 
+- [Getting started](part2/getting-started.md)
 - [Work in progress](part2/wip.md)
 
 # Part Ⅲ — Our second game

src/part2/getting-started.md

@@ -0,0 +1,118 @@
+# Getting started
+
+In this lesson we will start a new project from scratch, a [Breakout](https://en.wikipedia.org/wiki/Breakout_%28video_game%29) (also known as [Arkanoid](https://en.wikipedia.org/wiki/Arkanoid)) clone called "Unbricked"! (Or any other name you like, as this is *your* project)
+
+Open a terminal and make a new directory (`mkdir unbricked`), and then enter it (`cd unbricked`), just like you did for "Hello, world!".
+
+Start by creating a file called `main.asm`, and include `hardware.inc` in your code.
+
+```
+line 1
+```
+
+Then create a header. Remember from part 1 that the header includes some information the Game Boy relies on, so you don't wanna accidentally leave it out.
+
+```
+lines 3-7
+```
+
+The header jumps to `EntryPoint`, so let's write that now:
+
+```
+lines 9-18
+```
+
+The next few lines wait until "VBlank".
+VBlank basically means that the Game Boy's PPU has gone to sleep for a short time, during which we can do things like turning off the screen. 
+
+Turning off the screen is important because the PPU may wake back up at while we're still working.
+By turning the screen off completely, we ensure that our code won't be interrupted.
+You can only load new graphics while the PPU is sleeping, so this gives us as much time as we need to load our tiles.
+
+Speaking of tiles, we're going to load some into VRAM next, using the following code:
+```
+lines 20-31
+```
+
+This loop might look familiar if you've read part 1.
+It copies `Tiles` to `$9000`, which is the part of VRAM where tiles are stored.
+To get the length of `Tiles` we use another label at the end, called `TilesEnd`, and subtract the two to find the difference.
+
+Note that our code still doesn't have a lable called `Tiles`.
+We'll get to that later!
+
+We're almost done now.
+Next, write another loop, this time for copying the tilemap, which will organize our tiles on the screen.
+
+```
+lines 33-44
+```
+
+You might notice that while this code is exactly the same, the 3 values loaded into `de`, `hl`, and `bc` are different.
+These determine the source, destination, and size of the copy, respectively.
+
+Finally, we are going to turn the screen back on and initialize a background palette.
+hardware.inc provides the constants `LCDCF_ON` and `LCDCF_BGON`, which enable the screen and the background.
+We must "combine" these together using `|` (the or operator).
+
+```
+lines 46-55
+```
+
+There's one last thing we need before we can build the rom, and that's our graphics.
+We're going to be drawing the following screen:
+
+![Layout of unbricked](https://github.com/ISSOtm/gb-asm-tutorial-part2/blob/main/tilemap.png?raw=true)
+
+In the "Hello, world!" lesson, you saw graphics which were written out by hand in hexadecimal.
+This time, we're going to write our graphics in a more friendly way; by assigning a character to each shade.
+To do this, type `dw`, followed by a space, a backtick (\`) and a series of 8 characters; by default these are 0, 1, 2, and 3, going from lightest to darkest.
+This defines a row of 8 pixels.
+
+```rgbasm,linenos
+; For example:
+Tiles:
+	dw `01230123
+```
+
+(A note about OPT g could be added here?)
+
+We already have tiles made for this project, so you can copy [this premade file](https://github.com/ISSOtm/gb-asm-tutorial-part2/raw/main/tileset.asm), and paste it at the end of your code.
+
+Then copy the tilemap from [this file](https://github.com/ISSOtm/gb-asm-tutorial-part2/raw/main/tilemap.asm), and paste it after the `TilesEnd` label.
+
+You can try building the rom at this point, using the following commands in your terminal:
+
+```console
+$ rgbasm -L -o main.o main.asm
+$ rgblink -o unbricked.gb main.o
+$ rgbfix -v -p 0xFF unbricked.gb
+```
+
+If you run this in your emulator, you should see the following:
+
+(Screenshot pending :P)
+
+That white square seems to be missing!
+If you paid attention to your tiles earlier, you may have noticed this comment:
+
+```
+lines 135-140
+```
+
+The logo tiles were left intentionally blank so that you could customize this project.
+If you feel up to it, you can try creating your own logo by hand, or you can copy one of the following logos into your code:
+
+## RGBDS Logo
+[Source](https://github.com/ISSOtm/gb-asm-tutorial-part2/raw/main/rgbds.asm)
+![The RGBDS Logo](https://github.com/ISSOtm/gb-asm-tutorial-part2/blob/main/rgbds.png?raw=true)
+
+## Duck
+[Source](https://github.com/ISSOtm/gb-asm-tutorial-part2/raw/main/duck.asm)
+![A pixel-art duck](https://github.com/ISSOtm/gb-asm-tutorial-part2/blob/main/duck.png?raw=true)
+
+## Tail
+[Source](https://github.com/ISSOtm/gb-asm-tutorial-part2/raw/main/tail.asm)
+![A silhouette of a tail](https://github.com/ISSOtm/gb-asm-tutorial-part2/blob/main/tail.png?raw=true)
+
+Build your game again and your logo of choice should appear in the bottom right!