diff --git a/assets/disk0/tvdos/bin/defrag.js b/assets/disk0/tvdos/bin/defrag.js
new file mode 100644
index 0000000..3589379
--- /dev/null
+++ b/assets/disk0/tvdos/bin/defrag.js
@@ -0,0 +1,18 @@
+
+let drive = _G.shell.getCurrentDrive()
+let port = _TVDOS.DRV.FS.SERIAL._toPorts(drive)
+    com.sendMessage(port[0], "CLOSE")
+for (let i = 0; i < 20; i++) {
+    com.sendMessage(port[0], "READCLUST"+i)
+    let response = com.getStatusCode(port[0])
+    if (response < 0 || response >= 128) {
+        throw Error(`Reading cluster #${i} failed with `+response)
+    }
+    let bytes = com.pullMessage(port[0])
+    print(`#${i}\t`)
+    for (let k = 0; k < 16; k++) {
+        print(bytes.charCodeAt(k).toString(16).padStart(2, '0'))
+        print(' ')
+    }
+    println()
+}
\ No newline at end of file
diff --git a/tsvm_core/src/net/torvald/tsvm/peripheral/TevdDiskDrive.kt b/tsvm_core/src/net/torvald/tsvm/peripheral/TevdDiskDrive.kt
index bcdfacd..5b90bc2 100644
--- a/tsvm_core/src/net/torvald/tsvm/peripheral/TevdDiskDrive.kt
+++ b/tsvm_core/src/net/torvald/tsvm/peripheral/TevdDiskDrive.kt
@@ -339,6 +339,15 @@ class TevdDiskDrive(private val vm: VM, private val driveNum: Int, theTevdPath:
                 fileOpenMode = -1
                 statusCode.set(STATE_CODE_STANDBY)
             }
+            else if (inputString.startsWith("READCLUST")) {
+                if (fileOpen) {
+                    statusCode.set(STATE_CODE_FILE_ALREADY_OPENED)
+                    return
+                }
+                val clustnum = inputString.substring(9 until inputString.length).toInt()
+                resetBuf()
+                messageComposeBuffer.write(DOM.getRawCluster(clustnum))
+            }
             else if (inputString.startsWith("READ")) {
                 //readModeLength = inputString.substring(4 until inputString.length).toInt()