diff --git a/Instruction-Encoding.md b/Instruction-Encoding.md
index 9e5a031..47d7a0d 100644
--- a/Instruction-Encoding.md
+++ b/Instruction-Encoding.md
@@ -20,4 +20,16 @@ Selectors are 5-bit values that determine the addressing mode and registers invo
 | MEMORY_IMM16 | `11110` | |
 | MEMORY_REG16 | | |
 | MEMORY_REG_DISP16 | | |
-| IMMEDIATE16 | `11111` | |
\ No newline at end of file
+| IMMEDIATE16 | `11111` | |
+
+### Register Indexes
+| Register | Number | Bit-pattern |
+| --- | --- | --- |
+| A | | |
+| B | | |
+| C | | |
+| D | | |
+| X | | |
+| Y | | |
+| SP | | |
+| BP | | |
\ No newline at end of file