file/data: minor updates to file systems, DNA in SGBuffet

lectures/file-and-data-systems/slides.qmd

@@ -247,10 +247,11 @@ total 24
 
 ## Links
 
-* More than one name possible ("hard links")
+* An inode may have more than one name ("hard links")
   * More than one directory with same name
   * More than one name in one directory
 * inode's life time managed by "link count"
+  * Link count 0 labels inode and blocks as recyclable
 
 ## Links in action
 
@@ -352,3 +353,15 @@ The file system becomes an independent system.
 ## Symbolic links (symlinks)
 
 _Symbolic_ links are inodes referring to _paths_ instead of data
+
+## DNA encoding of data
+
+* Repeating nucleotides are problematic
+* Using "Trits" referring to previous nucleotide
+
+| Previous | 0 | 1 | 2 |
+| - | - | - | - |
+| Thymine | A | C | G |
+| Guanine | T | A | C |
+| Cytosine | G | T | A |
+| Adenine | C | G | T |