-@item disk.c
-@itemx disk.h
-Supports reading and writing sectors on up to 4 IDE disks. This won't
-actually be used until project 2.
+@item block.c
+@itemx block.h
+An abstraction layer for @dfn{block devices}, that is, random-access,
+disk-like devices that are organized as arrays of fixed-size blocks.
+Out of the box, Pintos supports two types of block devices: IDE disks
+and partitions. Block devices, regardless of type, won't actually be
+used until project 2.
+
+@item ide.c
+@itemx ide.h
+Supports reading and writing sectors on up to 4 IDE disks.
+
+@item partition.c
+@itemx partition.h
+Understands the structure of partitions on disks, allowing a single
+disk to be carved up into multiple regions (partitions) for
+independent use.