diff --git a/modules/pcjs/lib/bus.js b/modules/pcjs/lib/bus.js
index 6f73cd589..c007d001c 100644
--- a/modules/pcjs/lib/bus.js
+++ b/modules/pcjs/lib/bus.js
@@ -41,12 +41,21 @@ if (typeof module !== 'undefined') {
 }
 
 /**
- * @class BackTrack
- * @property {Object} obj
- * @property {number} off
- * @property {number} slot
- * @property {number} refs
+ * BackTrack objects have the following properties:
+ *
+ *      obj:    a reference to the source object (eg, ROM object, Sector object)
+ *      off:    the offset within the source object that this object refers to
+ *      slot:   the slot (+1) in abtObjects which this object currently occupies
+ *      refs:   the number of memory references, as recorded by writeBackTrack()
+ *
+ * @typedef {{
+ *  obj:    Object,
+ *  off:    number,
+ *  slot:   number,
+ *  refs:   number
+ * }}
  */
+var BackTrack;
 
 /**
  * Bus(cpu, dbg)
@@ -173,14 +182,6 @@ function Bus(parmsBus, cpu, dbg)
     this.initMemory();
 
     if (BACKTRACK) {
-        /*
-         * BackTrack objects have the following properties:
-         *
-         *      obj:    a reference to the source object (eg, ROM object, Sector object)
-         *      off:    the offset within the source object that this object refers to
-         *      slot:   the slot (+1) in abtObjects which this object currently occupies
-         *      refs:   the number of memory references, as recorded by writeBackTrack()
-         */
         this.abtObjects = [];
         this.cbtDeletions = 0;
         this.ibtLastAlloc = -1;
@@ -854,9 +855,9 @@ Bus.prototype.setLongDirect = function(addr, l)
  *
  * @this {Bus}
  * @param {Object} obj
- * @param {Object} bto
+ * @param {BackTrack} bto
  * @param {number} off (the offset within obj that this wrapper object is relative to)
- * @return {Object|null}
+ * @return {BackTrack|null}
  */
 Bus.prototype.addBackTrackObject = function(obj, bto, off)
 {
@@ -910,7 +911,7 @@ Bus.prototype.addBackTrackObject = function(obj, bto, off)
  * getBackTrackIndex(bto, off)
  *
  * @this {Bus}
- * @param {Object|null} bto
+ * @param {BackTrack|null} bto
  * @param {number} off
  * @return {number}
  */
@@ -928,7 +929,7 @@ Bus.prototype.getBackTrackIndex = function(bto, off)
  *
  * @this {Bus}
  * @param {number} addr is a physical (non-segmented) address
- * @param {Object|null} bto
+ * @param {BackTrack|null} bto
  * @param {number} off
  */
 Bus.prototype.writeBackTrackObject = function(addr, bto, off)
diff --git a/modules/pcjs/lib/disk.js b/modules/pcjs/lib/disk.js
index ed663e5ed..d1700bd8c 100644
--- a/modules/pcjs/lib/disk.js
+++ b/modules/pcjs/lib/disk.js
@@ -229,26 +229,18 @@ function Disk(controller, drive, mode)
 }
 
 /**
- * @class File
- * @property {string} sPath
- * @property {string} sName
- * @property {number} bAttr
- * @property {number} cbSize
- * @property {Array.<number>} apba
- * @property {Disk} disk
+ * @typedef {{
+ *  sPath:  string,
+ *  sName:  string,
+ *  bAttr:  number,
+ *  cbSize: number,
+ *  apba:   Array.<number>,
+ *  disk:   Disk
+ * }}
  */
+var FileInfo;
 
 /**
- * @class Sector
- * @property {number} sector
- * @property {number} length
- * @property {Array.<number>} data
- * @property {number|null} pattern
- * @property {number} iCylinder
- * @property {number} iHead
- * @property {number} iModify
- * @property {number} cModify
- *
  * Every Sector object (once loaded and fully parsed) should have ALL of the following named properties:
  *
  *      'sector':   sector number
@@ -277,7 +269,19 @@ function Disk(controller, drive, mode)
  *
  * TODO: Perhaps we should also maintain a failure count and stop trying to write sectors that reach a certain
  * threshold.  Error-handling, as usual, is the thorniest problem.
+ *
+ * @typedef {{
+ *  sector:     number,
+ *  length:     number,
+ *  data:       Array.<number>,
+ *  pattern:    (number|null),
+ *  iCylinder:  number,
+ *  iHead:      number,
+ *  iModify:    number,
+ *  cModify:    number
+ * }}
  */
+var SectorData;
 
 /**
  * @class SectorInfo