add README.md

.gitignore

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 *
 !*/
 !Makefile
+!README.md
 !.gitignore
 !init.sh

README.md

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+# ICS2017 Programming Assignment
+
+This project is the programming assignment of the class ICS(Introduction to Computer System) in Department of Computer Science and Technology, Nanjing University.
+
+For the guide of this programming assignment,
+refer to http://nju-ics.gitbooks.io/ics2017-programming-assignment/content/
+
+To initialize, run
+```bash
+bash init.sh
+```
+
+The following subprojects/components are included. Some of them are not fully implemented.
+* [NEMU](https://github.com/NJU-ProjectN/nemu)
+* [Nexus-am](https://github.com/NJU-ProjectN/nexus-am)
+* [Nanos-lite](https://github.com/NJU-ProjectN/nanos-lite)
+* [Navy-apps](https://github.com/NJU-ProjectN/navy-apps)