Update README.md

README.md

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-# 6502-npp-syntax
+# Notepad++ Syntax Highlighting for 6502 Assembly
+
+## Introduction
+I started programming an NES game in 6502 assembly but couldn't find any syntax highlighting files anywhere, so I ended up making my own. 
+
+There are two files included here:
+- **npp_6502_general.xml**, which highlights opcodes, numbers, comments, etc. for the 6502 assembly language
+- **npp_6502_nesasm.xml**, which does the same thing, but also highlights assembler directives and functions for NESASM3
+
+## Installation
+1.  Download **npp_6502_general.xml** or **npp_6502_nesasm.xml**.
+1.  In Notepad++, go to *Language* -> *Define your language...*
+1.  Click *Import...* and select the file.
+1.  Restart Notepad++.
+1.  Go to *Language* and select *6502 Assembly* to load the syntax highlighting.
+1.  If you use a theme, go to *Settings* -> *Style Configurator* and check *Enable global background color*.
+
+## Features
+- Highlights opcodes, comments, numbers, and strings
+- Separate colors for integers, hex, and binary numbers
+- Special highlighting for immediate addressing symbol (#)
+- Special highlighting for registers (A, X, Y, S, P)
+- Opcodes can be entered in upper or lower case
+- Illegal opcodes are recognized and differentiated with a darker color
+
+## Notes
+I've left off the automatic extension checking for `.asm` files because it would overlap with other types of assembly files, but if you'd like to make this highlighting the default for all `.asm` files, just add **"asm"** to the *Ext.* box in *Language* -> *Define your language...*