diff --git a/README.md b/README.md
index 558528d..fdfe818 100644
--- a/README.md
+++ b/README.md
@@ -7,3 +7,8 @@ http://www.tuhs.org/Archive/PDP-11/Distributions/research/McIlroy_v0/
 as the files 0*.pdf. We now need to convert these to machine-readable
 assembly code, write tools such as an assembler, a filesystem creation tool,
 and write from scratch missing things like a shell, ls etc.
+
+scans/	  holds the unmodified OCR versions of the scanned files
+src/cmd   holds the modified source code of the user-mode programs
+src/sys   holds the modified source code of the kernel
+tools/	  holds the source for the tools written to assist the project