diff --git a/bootloader/main.asm b/bootloader/main.asm
index a47cc0e..9a52906 100644
--- a/bootloader/main.asm
+++ b/bootloader/main.asm
@@ -3,7 +3,7 @@ DISK_ID EQU 0x80
 KERNEL_START EQU 0x100000
 ELF_START EQU 0x8000
 
-NUM_SECTORS EQU 21
+NUM_SECTORS EQU 65
 
 org 0x7C00
 bits 16
diff --git a/docs/bootloader.md b/docs/bootloader.md
new file mode 100644
index 0000000..bb781f1
--- /dev/null
+++ b/docs/bootloader.md
@@ -0,0 +1,29 @@
+# RoBootloader
+
+## Low Memory
+
+| start   | end     | use                       |
+|---------|---------|---------------------------|
+| 0x00000 | 0x004ff | BIOS stuff, don't touch   |
+| 0x00500 | 0x06bff | _free space_              |
+| 0x06c00 | 0x07bff | **Bootloader stack**      |
+| 0x07c00 | 0x07dff | Bootloader                |
+| 0x07e00 | 0x07fff | _free space_              |
+| 0x08000 | 0x0ffff | **ELF file** (64 sectors) |
+| 0x10000 | 0x7ffff | **kernel space**          |
+| 0x80000 | 0x9ffff | EDBA, partially usable    |
+| 0xa0000 | 0xfffff | unusable                  |
+
+## Drive layout
+
+The first 512 bytes are the bootloader, right after that the 32-bit kernel ELF-file, this kernel can be 32KiB big. In the future, this "kernel" can be replaced by a second stage of the bootloader.
+
+## Known issues
+
+### USB Boot
+
+It doesn't boot the kernel from USB, as BIOS does not recognize USB as valid hard drive for int 13, only hard drives and floppies. Thus it loads sectors 2-65 from the hard drive. If this is written on a hard drive, it could work if DRIVE_ID is set correctly.
+
+### Stack setup
+
+As I don't quite get how segments work in real mode, there are most likely errors in the way I set up my stack. I'm going on a _it works on my qemu_ approach currently.