diff --git a/doc/maint/-read-.-this- b/doc/maint/-read-.-this-
index 91999c87..821cc1d4 100755
--- a/doc/maint/-read-.-this-
+++ b/doc/maint/-read-.-this-
@@ -1,2 +1,18 @@
-                  	@.dzdhe
-F __DZD
\ No newline at end of file
+This directory contains diagnostics.  This file contains some theories
+and guesses.
+
+The PART * files are probably for KA10 and KL10.  Some timestamps are
+from 1971 which is long before the KL10.  Others are from 1975 which
+is right about when MIT would have gotten their first KL10.  Some of
+the .OLD files check KA10 behavior, such as K.OLD which runs an
+overflowing AOBJN.  KS10 passes all files except PART K.  To run the
+diagnostics, load and run PART A; it will run the next part
+automatically until PART M which starts over.
+
+The PDP6 * files are for the PDP-6.
+
+The SAV files are KL10 & KI10 basic instruction diagnostics and can be
+run with DECUUO.  These work on a KA10: DEKAA, DEKAB, DEKAC, DEKAE,
+and DEKAF.  DEKAD and DEKAG work on a KS10, but not DEKAF.
+
+TST342 displays all characters supported by the Type 342 character generator.