diff --git a/serialdev.txt b/serialdev.txt
index 133d715..b9cf02e 100644
--- a/serialdev.txt
+++ b/serialdev.txt
@@ -57,7 +57,7 @@ Description: reads status of the device, if applicable
 Returns:
     0x06 <status code> <0x1F> <message string> 0x17
     0x15 <status code> <0x1F> <message string> 0x17
-(see section 1.0)
+Status Code is single byte number. Also see section 1.0
 
 2. Device-specific commands
 
diff --git a/src/net/torvald/tsvm/FilesystemDelegate.kt b/src/net/torvald/tsvm/FilesystemDelegate.kt
index 3c84b55..dd3ae12 100644
--- a/src/net/torvald/tsvm/FilesystemDelegate.kt
+++ b/src/net/torvald/tsvm/FilesystemDelegate.kt
@@ -9,7 +9,7 @@ class VmFilesystemDelegate(val vm: VM, val portNo: Int) {
 
 }
 
-class DiskDriveFileInputStream(vm: VM, portNo: Int, path: String) : InputStream() {
+class DiskDriveFileInputStream(val vm: VM, val portNo: Int, val path: String) : InputStream() {
 
     private val contents: ByteArray
     private var readCursor = 0
@@ -60,7 +60,7 @@ class DiskDriveFileInputStream(vm: VM, portNo: Int, path: String) : InputStream(
     }
 
     override fun close() {
-        TODO()
+        SerialHelper.sendMessage(vm, portNo, "CLOSE".toByteArray(VM.CHARSET))
     }
 }
 
diff --git a/src/net/torvald/tsvm/SerialHelper.kt b/src/net/torvald/tsvm/SerialHelper.kt
index 9042dd6..51bb8bd 100644
--- a/src/net/torvald/tsvm/SerialHelper.kt
+++ b/src/net/torvald/tsvm/SerialHelper.kt
@@ -3,6 +3,7 @@ package net.torvald.tsvm
 import net.torvald.UnsafeHelper
 import net.torvald.terrarum.modulecomputers.virtualcomputer.tvd.toUint
 import net.torvald.tsvm.peripheral.BlockTransferInterface.Companion.BLOCK_SIZE
+import net.torvald.tsvm.peripheral.BlockTransferInterface.Companion.END_OF_SEND_BLOCK
 import java.io.ByteArrayOutputStream
 import kotlin.experimental.and
 import kotlin.experimental.or
@@ -52,6 +53,15 @@ object SerialHelper {
         return msgBuffer.toByteArray()
     }
 
+    fun getDeviceStatus(vm: VM, portNo: Int): DeviceStatus {
+        val msgStr = sendMessageGetBytes(vm, portNo, "DEVSTU$END_OF_SEND_BLOCK".toByteArray(VM.CHARSET))
+        return DeviceStatus(
+            msgStr[0] == 0x06.toByte(),
+            msgStr[1].toUint(),
+            msgStr.sliceArray(3 until msgStr.size - 1).toString(VM.CHARSET)
+        )
+    }
+
     fun waitUntilReady(vm: VM, portNo: Int) {
         while (!checkIfDeviceIsReady(vm, portNo)) { Thread.sleep(SLEEP_TIME) }
     }
@@ -87,4 +97,6 @@ object SerialHelper {
 
 
     private fun Boolean.toInt() = if (this) 1 else 0
+
+    data class DeviceStatus(val isError: Boolean, val code: Int, val message: String)
 }
\ No newline at end of file
diff --git a/src/net/torvald/tsvm/peripheral/TestDiskDrive.kt b/src/net/torvald/tsvm/peripheral/TestDiskDrive.kt
index c9083c6..2e75643 100644
--- a/src/net/torvald/tsvm/peripheral/TestDiskDrive.kt
+++ b/src/net/torvald/tsvm/peripheral/TestDiskDrive.kt
@@ -12,6 +12,7 @@ class TestDiskDrive(private val driveNum: Int) : BlockTransferInterface(false, t
         const val STATE_CODE_STANDBY = 0
         const val STATE_CODE_ILLEGAL_COMMAND = 128
         const val STATE_CODE_FILE_NOT_FOUND = 129
+        const val STATE_CODE_FILE_ALREADY_OPENED = 130
         const val STATE_CODE_SYSTEM_IO_ERROR = 192
 
 
@@ -21,6 +22,7 @@ class TestDiskDrive(private val driveNum: Int) : BlockTransferInterface(false, t
             errorMsgs[STATE_CODE_STANDBY] = "READY"
             errorMsgs[STATE_CODE_ILLEGAL_COMMAND] = "SYNTAX ERROR"
             errorMsgs[STATE_CODE_FILE_NOT_FOUND] = "FILE NOT FOUND"
+            errorMsgs[STATE_CODE_FILE_ALREADY_OPENED] = "FILE ALREADY OPENED"
             errorMsgs[STATE_CODE_SYSTEM_IO_ERROR] = "IO ERROR ON SIMULATED DRIVE"
         }
     }
@@ -139,6 +141,10 @@ class TestDiskDrive(private val driveNum: Int) : BlockTransferInterface(false, t
             //startSend { it.writeout(composePositiveAns("Testtec Virtual Disk Drive")) }
             recipient?.writeout(composePositiveAns("Testtec Virtual Disk Drive"))
         else if (inputString.startsWith("OPENR\"") || inputString.startsWith("OPENW\"") || inputString.startsWith("OPENA\"")) {
+            if (file != null) {
+                stateCode = STATE_CODE_FILE_ALREADY_OPENED
+                return
+            }
 
             val openMode = inputString[4]