diff --git a/pom.xml b/pom.xml
index 0699d0dd9..ea5a3b461 100644
--- a/pom.xml
+++ b/pom.xml
@@ -356,6 +356,13 @@
             <version>2.0.6</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.github.stefanbirkner</groupId>
+            <artifactId>system-rules</artifactId>
+            <version>1.19.0</version>
+            <scope>test</scope>
+        </dependency>
+
     </dependencies>
 
     <scm>
diff --git a/src/main/java/de/neemann/digital/core/element/Keys.java b/src/main/java/de/neemann/digital/core/element/Keys.java
index 350f900aa..00b3ba04a 100644
--- a/src/main/java/de/neemann/digital/core/element/Keys.java
+++ b/src/main/java/de/neemann/digital/core/element/Keys.java
@@ -1028,4 +1028,10 @@ private static File getATMISPPath() {
      */
     public static final Key<Boolean> SKIP_HDL =
             new Key<>("skipHDL", false).setSecondary();
+
+    /**
+     * verilog code lib path, find include and depends
+     */
+    public static final Key<File> SETTINGS_VERILOG_LIB_DIR =
+            new Key.KeyFile("verilogLib", new File("")).setDirectoryOnly(true).setSecondary();
 }
diff --git a/src/main/java/de/neemann/digital/core/extern/Application.java b/src/main/java/de/neemann/digital/core/extern/Application.java
index aaec952a7..badf47b6c 100644
--- a/src/main/java/de/neemann/digital/core/extern/Application.java
+++ b/src/main/java/de/neemann/digital/core/extern/Application.java
@@ -65,7 +65,11 @@ enum Type {
         /**
          * Icarus verilog interpreter
          */
-        IVERILOG
+        IVERILOG,
+        /**
+         * extern socket app interpreter
+         */
+        Socket
     }
 
     /**
@@ -83,6 +87,8 @@ static Application create(Type type, ElementAttributes attr) {
                 return new ApplicationGHDL(attr);
             case IVERILOG:
                 return new ApplicationIVerilog(attr);
+            case Socket:
+                return new ApplicationSocket();
             default:
                 return null;
         }
diff --git a/src/main/java/de/neemann/digital/core/extern/ApplicationIVerilog.java b/src/main/java/de/neemann/digital/core/extern/ApplicationIVerilog.java
index 9228cbc38..cdaef6028 100644
--- a/src/main/java/de/neemann/digital/core/extern/ApplicationIVerilog.java
+++ b/src/main/java/de/neemann/digital/core/extern/ApplicationIVerilog.java
@@ -29,6 +29,7 @@ public class ApplicationIVerilog extends ApplicationVerilogStdIO {
     private String iverilogFolder;
     private String iverilog;
     private String vvp;
+    private String verilogLibPath;
 
     /**
      * Initialize a new instance
@@ -39,6 +40,21 @@ public ApplicationIVerilog(ElementAttributes attr) {
         this.attr = attr;
         iverilogFolder = "";
         hasIverilog = findIVerilog();
+        verilogLibPath = getVerilogLibPath();
+    }
+
+    /**
+     * verilog code lib path, find includes and depends code
+     * support config with env vars
+     * @return lib path
+     */
+    private String getVerilogLibPath() {
+        String libPath = Settings.getInstance().get(Keys.SETTINGS_VERILOG_LIB_DIR).getAbsolutePath();
+        if (libPath == null || libPath.equals("")) {
+            return "";
+        }
+        libPath = "-y"+ApplicationIVerilog.replaceEnvVars(libPath);
+        return libPath;
     }
 
     @Override
@@ -60,6 +76,7 @@ public ProcessInterface start(String label, String code, PortDefinition inputs,
                     .add("-o")
                     .add(testOutputName)
                     .add(attr, Keys.IVERILOG_OPTIONS)
+                    .addString(this.verilogLibPath)
                     .add(file.getName())
                     .getArray()
             );
@@ -106,6 +123,7 @@ public String checkCode(String label, String code, PortDefinition inputs, PortDe
                     .add("-o")
                     .add(testOutputName)
                     .add(attr, Keys.IVERILOG_OPTIONS)
+                    .addString(this.verilogLibPath)
                     .add(file.getName())
                     .getArray()
             );
diff --git a/src/main/java/de/neemann/digital/core/extern/ApplicationSocket.java b/src/main/java/de/neemann/digital/core/extern/ApplicationSocket.java
new file mode 100644
index 000000000..a65cde4b0
--- /dev/null
+++ b/src/main/java/de/neemann/digital/core/extern/ApplicationSocket.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2024 Ron Ren.
+ * Use of this source code is governed by the GPL v3 license
+ * that can be found in the LICENSE file.
+ */
+package de.neemann.digital.core.extern;
+
+import de.neemann.digital.core.extern.handler.ProcessInterface;
+import de.neemann.digital.core.extern.handler.SocketInterface;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * application with shared mem map file comm
+ */
+public class ApplicationSocket implements Application {
+    @Override
+    public ProcessInterface start(String label, String code, PortDefinition inputs, PortDefinition outputs, File root) throws IOException {
+        String ipPort = "127.0.0.1:8009";
+        if (code.length() > 0 && code.indexOf(":") > 0) {
+            ipPort = code;
+        }
+        return new SocketInterface(ipPort, inputs, outputs);
+    }
+
+    @Override
+    public boolean checkSupported() {
+        return true;
+    }
+
+    @Override
+    public String checkCode(String label, String code, PortDefinition inputs, PortDefinition outputs, File root) throws IOException {
+        return null;
+    }
+
+}
diff --git a/src/main/java/de/neemann/digital/core/extern/ApplicationVerilogStdIO.java b/src/main/java/de/neemann/digital/core/extern/ApplicationVerilogStdIO.java
index e8ac90af5..6a8b97b56 100644
--- a/src/main/java/de/neemann/digital/core/extern/ApplicationVerilogStdIO.java
+++ b/src/main/java/de/neemann/digital/core/extern/ApplicationVerilogStdIO.java
@@ -16,6 +16,8 @@
 import java.io.*;
 import java.nio.file.Files;
 import java.util.NoSuchElementException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 
 /**
@@ -208,6 +210,30 @@ private void scanPort(VerilogTokenizer st, PortDefinition in, PortDefinition out
         }
     }
 
+    /**
+     * replace env string in options
+     * @param input option string
+     * @return replace every ${xx} env vars
+     */
+    public static String replaceEnvVars(String input) {
+        Pattern pattern = Pattern.compile("(?<!\\\\)\\$\\{([^}]+)\\}");
+        Matcher matcher = pattern.matcher(input);
+        StringBuffer result = new StringBuffer();
+
+        while (matcher.find()) {
+            String varName = matcher.group(1);
+            String envValue = System.getenv(varName);
+            if (envValue == null) {
+                envValue = "";
+            }
+            matcher.appendReplacement(result, envValue);
+        }
+
+        matcher.appendTail(result);
+
+        return result.toString().replace("\\$", "$").replace("\\", "\\\\");
+    }
+
     private static final class ParseException extends Exception {
         private ParseException(String message) {
             super(message);
diff --git a/src/main/java/de/neemann/digital/core/extern/handler/SocketInterface.java b/src/main/java/de/neemann/digital/core/extern/handler/SocketInterface.java
new file mode 100644
index 000000000..40d36a659
--- /dev/null
+++ b/src/main/java/de/neemann/digital/core/extern/handler/SocketInterface.java
@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2024 Ron Ren.
+ * Use of this source code is governed by the GPL v3 license
+ * that can be found in the LICENSE file.
+ */
+package de.neemann.digital.core.extern.handler;
+
+import de.neemann.digital.core.ObservableValue;
+import de.neemann.digital.core.ObservableValues;
+import de.neemann.digital.core.extern.Port;
+import de.neemann.digital.core.extern.PortDefinition;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.BitSet;
+
+/**
+ * signal comm out from extern app with shared mem map file
+ */
+public class SocketInterface implements ProcessInterface {
+
+    private TCPClient tcpClient;
+
+    private int inputBits;
+    private int outputBits;
+    private BitSet inSeta;
+    private BitSet inSetb;
+    private int inLen;
+    private BitSet outSet;
+    private ByteBuffer buf1;
+    private ByteBuffer buf2;
+
+
+    /**
+     * mem map init
+     * @param ipPort  address and port for extern
+     * @param inputs signal inputs
+     * @param outputs  signal outputs
+     */
+    public SocketInterface(String ipPort, PortDefinition inputs, PortDefinition outputs) {
+        String[] net = ipPort.split(":");
+        this.tcpClient = new TCPClient(net[0], Integer.parseInt(net[1]));
+        this.inputBits = 0;
+        this.outputBits = 0;
+        for (Port input : inputs) {
+            this.inputBits += input.getBits();
+            this.inLen = this.inputBits;
+            // match the VPI t_vpi_value type,t_vpi_vecval use aval and bval with int32
+            while (this.inLen % 32 != 0) {
+                this.inLen++;
+            }
+            this.inSeta = new BitSet(this.inLen);
+            this.inSetb = new BitSet(this.inLen);
+            this.buf1 = ByteBuffer.allocate(this.inLen/8);
+            this.buf2 = ByteBuffer.allocate(this.inLen/8);
+        }
+        for (Port output : outputs) {
+            this.outputBits += output.getBits();
+        }
+    }
+
+    private void initSocket() throws IOException {
+        if (!this.tcpClient.getIsRunning()) {
+            this.tcpClient.start();
+        }
+    }
+
+    private static byte[] concatenateByteArrays(byte[] array1, byte[] array2) {
+        byte[] result = new byte[array1.length + array2.length]; // 新数组，长度为两个数组的总和
+
+        System.arraycopy(array1, 0, result, 0, array1.length); // 将array1复制到result
+        System.arraycopy(array2, 0, result, array1.length, array2.length); // 将array2复制到result
+
+        return result;
+    }
+
+    @Override
+    public void writeValues(ObservableValues values) throws IOException {
+        this.initSocket();
+        int pos = 0;
+        for (ObservableValue v : values) {
+            for (int i=0; i<v.getBits(); i++) {
+                long mask =  (1L << i);
+                long value = v.getValue() & mask;
+                long hZ = v.getHighZ() & mask;
+                /* ab encoding: 00=0, 10=1, 11=X, 01=Z */
+                if (value > 0) {
+                    this.inSeta.set(pos, true);
+                    this.inSetb.set(pos, false);
+                } else if (hZ > 0) {
+                    this.inSeta.set(pos, false);
+                    this.inSetb.set(pos, true);
+                } else {
+                    this.inSeta.set(pos, false);
+                    this.inSetb.set(pos, false);
+                }
+                pos++;
+            }
+        }
+        this.buf1.clear();
+        this.buf2.clear();
+        this.buf1.put(this.inSeta.toByteArray());
+        this.buf2.put(this.inSetb.toByteArray());
+        while (this.buf1.position() < this.inLen/8) {
+            this.buf1.put((byte) 0);
+        }
+        while (this.buf2.position() < this.inLen/8) {
+            this.buf2.put((byte) 0);
+        }
+        try {
+            this.tcpClient.sendMessage(SocketInterface.concatenateByteArrays(this.buf1.array(), this.buf2.array()));
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    public void readValues(ObservableValues values) throws IOException {
+        this.initSocket();
+        byte[] buf = this.tcpClient.receiveMessage();
+        if (buf == null) {
+            return;
+        }
+        int posAdd = (buf.length*8)/2;
+        this.outSet = BitSet.valueOf(buf);
+        int pos = 0;
+        for (ObservableValue v : values) {
+            long value = 0L;
+            long hZ = 0L;
+            for (int i=0; i<v.getBits(); i++) {
+                long mask =  (1L << i);
+                /* ab encoding: 00=0, 10=1, 11=X, 01=Z */
+                boolean l = this.outSet.get(pos);
+                boolean r = this.outSet.get(pos + posAdd);
+                if (l && !r) {
+                    value = value | mask;
+                } else if (!l && r) {
+                    hZ = hZ | mask;
+                }
+                pos++;
+            }
+            v.set(value, hZ);
+        }
+    }
+
+    @Override
+    public void close() throws IOException {
+        this.tcpClient.close();
+    }
+}
diff --git a/src/main/java/de/neemann/digital/core/extern/handler/TCPClient.java b/src/main/java/de/neemann/digital/core/extern/handler/TCPClient.java
new file mode 100644
index 000000000..fc40e0b8a
--- /dev/null
+++ b/src/main/java/de/neemann/digital/core/extern/handler/TCPClient.java
@@ -0,0 +1,156 @@
+/*
+ * Copyright (c) 2024 Ron Ren.
+ * Use of this source code is governed by the GPL v3 license
+ * that can be found in the LICENSE file.
+ */
+package de.neemann.digital.core.extern.handler;
+
+import java.io.*;
+import java.net.*;
+import java.util.concurrent.*;
+
+/**
+ * TCP CLIENT for extern
+ */
+public class TCPClient {
+    private String serverAddress;
+    private int serverPort;
+    private Socket socket;
+    private DataOutputStream output;
+    private DataInputStream input;
+
+    private BlockingQueue<byte[]> sendQueue = new LinkedBlockingQueue<byte[]>();
+    private volatile byte[] recvMsg;
+
+    private volatile boolean isRunning = false;
+
+    /**
+     * status
+     * @return current status
+     */
+    public boolean getIsRunning() {
+        return this.isRunning;
+    }
+
+    /***
+     * construction
+     * @param serverAddress  extern app ip address
+     * @param serverPort extern app port
+     */
+    public TCPClient(String serverAddress, int serverPort) {
+        this.serverAddress = serverAddress;
+        this.serverPort = serverPort;
+    }
+
+    /**
+     * start tcpclient
+     * @throws IOException exception
+     */
+    public void start() throws IOException {
+        if (this.socket == null || this.socket.isClosed() || !this.isRunning) {
+            socket = new Socket(serverAddress, serverPort);
+            this.output = new DataOutputStream(socket.getOutputStream());
+            this.input = new DataInputStream(socket.getInputStream());
+            this.isRunning = true;
+            new Thread(new Sender(this)).start();
+            new Thread(new Receiver(this)).start();
+        }
+    }
+
+    /***
+     * send message to extern app
+     * @param bytes  send bytes
+     * @throws InterruptedException put msg failed.
+     */
+    public void sendMessage(byte[] bytes) throws InterruptedException {
+        sendQueue.put(bytes);
+    }
+
+    /***
+     * get message from extern app
+     * @return current extern app signals
+     */
+    public byte[] receiveMessage() {
+        return recvMsg;
+    }
+
+    /***
+     * sender
+     */
+    private class Sender implements Runnable {
+        private TCPClient tcpClient;
+
+        /**
+         * construction
+         * @param tcpClient  tcpclient instance
+         */
+        Sender(TCPClient tcpClient) {
+            this.tcpClient = tcpClient;
+        }
+        @Override
+        public void run() {
+            try {
+                while (this.tcpClient.isRunning) {
+                    byte[] msg = sendQueue.take();
+                    this.tcpClient.output.writeInt(msg.length);
+                    this.tcpClient.output.write(msg);
+                    this.tcpClient.output.flush();
+                }
+            } catch (InterruptedException e) {
+                System.out.println("Sender interrupted.");
+                e.printStackTrace();
+            } catch (IOException e) {
+                e.printStackTrace();
+            } finally {
+                try {
+                    this.tcpClient.output.close();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+                this.tcpClient.isRunning = false;
+            }
+        }
+    }
+
+    /***
+     * Receiver
+     */
+    private class Receiver implements Runnable {
+        private TCPClient tcpClient;
+        /**
+         * construction
+         * @param tcpClient  tcpclient instance
+         */
+        Receiver(TCPClient tcpClient) {
+            this.tcpClient = tcpClient;
+        }
+        @Override
+        public void run() {
+            try {
+                while (this.tcpClient.isRunning) {
+                    int msgLen = this.tcpClient.input.readInt();
+                    this.tcpClient.recvMsg = new byte[msgLen];
+                    this.tcpClient.input.readFully(this.tcpClient.recvMsg);
+                }
+            } catch (IOException e) {
+                System.out.println("Receiver interrupted.");
+            } finally {
+                try {
+                    this.tcpClient.input.close();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+                this.tcpClient.isRunning = false;
+            }
+        }
+    }
+
+    /**
+     * close tcp connection
+     * @throws IOException exception
+     */
+    public void close() throws IOException {
+        this.isRunning = false;
+        socket.close();
+    }
+}
diff --git a/src/main/java/de/neemann/digital/gui/Settings.java b/src/main/java/de/neemann/digital/gui/Settings.java
index 25bdf6d09..cf8b96986 100644
--- a/src/main/java/de/neemann/digital/gui/Settings.java
+++ b/src/main/java/de/neemann/digital/gui/Settings.java
@@ -55,6 +55,7 @@ private static List<Key> createKeyList() {
         intList.add(Keys.SETTINGS_ATMISP);
         intList.add(Keys.SETTINGS_GHDL_PATH);
         intList.add(Keys.SETTINGS_IVERILOG_PATH);
+        intList.add(Keys.SETTINGS_VERILOG_LIB_DIR);
         intList.add(Keys.SETTINGS_TOOLCHAIN_CONFIG);
         intList.add(Keys.SETTINGS_FONT_SCALING);
         intList.add(Keys.SETTINGS_MAC_MOUSE);
diff --git a/src/main/resources/lang/lang_de.xml b/src/main/resources/lang/lang_de.xml
index 5fe453990..71f812c2d 100644
--- a/src/main/resources/lang/lang_de.xml
+++ b/src/main/resources/lang/lang_de.xml
@@ -1498,6 +1498,7 @@ Sind evtl. die Namen der Variablen nicht eindeutig?</string>
     <string name="key_applicationType_Generic">Generisch</string>
     <string name="key_applicationType_GHDL">GHDL</string>
     <string name="key_applicationType_IVERILOG">IVerilog</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_externalInputs">Eingänge</string>
     <string name="key_externalInputs_tt">Die Eingänge des externen Prozesses. Es handelt sich um eine kommaseparierte
         Liste mit Signalnamen. Bei jedem Signalnamen kann, mit einem Doppelpunkt getrennt, eine Bitanzahl angegeben werden.
@@ -1525,6 +1526,9 @@ Sind evtl. die Namen der Variablen nicht eindeutig?</string>
     <string name="key_iverilogPath_tt">Pfad zum Icarus-Verilog-Installationsordner. Nur notwendig, wenn Sie iverilog
         verwenden möchten, um mit Verilog definierte Komponenten zu simulieren.
     </string>
+    <string name="key_verilogLib">Verilog external code library path</string>
+    <string name="key_verilogLib_tt">Used to configure the dependency library path for Verilog code, which will automatically search for dependency code during simulation
+    </string>
     <string name="key_maxValue">Maximalwert</string>
     <string name="key_maxValue_tt">Wird hier eine Null eingetragen, wird der maximal mögliche Wert verwendet (Alle Bits
         sind Eins).
diff --git a/src/main/resources/lang/lang_en.xml b/src/main/resources/lang/lang_en.xml
index c595caef4..1384d79ba 100644
--- a/src/main/resources/lang/lang_en.xml
+++ b/src/main/resources/lang/lang_en.xml
@@ -1485,6 +1485,7 @@
     <string name="key_applicationType_Generic">Generic</string>
     <string name="key_applicationType_GHDL">GHDL</string>
     <string name="key_applicationType_IVERILOG">IVerilog</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_externalInputs">Inputs</string>
     <string name="key_externalInputs_tt">The inputs of the external process.
         It is a comma-separated list of signal names. For each signal name, a number of bits separated by a colon
@@ -1514,6 +1515,9 @@
         iverilog to simulate
         components defined with Verilog.
     </string>
+    <string name="key_verilogLib">Verilog external code library path</string>
+    <string name="key_verilogLib_tt">Used to configure the dependency library path for Verilog code, which will automatically search for dependency code during simulation
+    </string>
     <string name="key_maxValue">Maximum Value</string>
     <string name="key_maxValue_tt">If a zero is entered, the maximum possible value is used (all bits are one).</string>
 
diff --git a/src/main/resources/lang/lang_es.xml b/src/main/resources/lang/lang_es.xml
index 0394b10c7..d9d2aeed3 100644
--- a/src/main/resources/lang/lang_es.xml
+++ b/src/main/resources/lang/lang_es.xml
@@ -1125,6 +1125,7 @@ In the file howTo.md you can find more details about translations.
   <string name="key_applicationType_Generic">Genérica</string>
   <string name="key_applicationType_GHDL">GHDL</string>
   <string name="key_applicationType_IVERILOG">iVerilog</string>
+  <string name="key_applicationType_Socket">Socket</string>
   <string name="key_externalInputs">Entradas</string>
   <string name="key_externalInputs_tt">Entradas del proceso externo.
 		Es una lista de nombres de señales separadas por comas. Para cada nombre de señal, usando ":", puede indicarse
diff --git a/src/main/resources/lang/lang_es_ref.xml b/src/main/resources/lang/lang_es_ref.xml
index 9dff76a1d..888385963 100644
--- a/src/main/resources/lang/lang_es_ref.xml
+++ b/src/main/resources/lang/lang_es_ref.xml
@@ -1200,6 +1200,7 @@ In the file howTo.md you can find more details about translations.
     <string name="key_applicationType_Generic">Generic</string>
     <string name="key_applicationType_GHDL">GHDL</string>
     <string name="key_applicationType_IVERILOG">IVerilog</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_externalInputs">Inputs</string>
     <string name="key_externalInputs_tt">The inputs of the external process.
         It is a comma-separated list of signal names. For each signal name, a number of bits separated by a colon
@@ -1221,6 +1222,9 @@ In the file howTo.md you can find more details about translations.
         iverilog to simulate
         components defined with Verilog.
     </string>
+    <string name="key_verilogLib">Verilog external code library path</string>
+    <string name="key_verilogLib_tt">Used to configure the dependency library path for Verilog code, which will automatically search for dependency code during simulation
+    </string>
     <string name="key_maxValue">Maximum Value</string>
     <string name="key_maxValue_tt">If a zero is entered, the maximum possible value is used (all bits are one).</string>
     <string name="key_dipDefault">Output is High</string>
diff --git a/src/main/resources/lang/lang_fr.xml b/src/main/resources/lang/lang_fr.xml
index 23d049c21..af426262d 100644
--- a/src/main/resources/lang/lang_fr.xml
+++ b/src/main/resources/lang/lang_fr.xml
@@ -1550,6 +1550,7 @@ In the file howTo.md you can find more details about translations.
     <string name="key_applicationType_Generic">Générique</string>
     <string name="key_applicationType_GHDL">GHDL</string>
     <string name="key_applicationType_IVERILOG">IVerilog</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_externalInputs">Entrées</string>
     <string name="key_externalInputs_tt">Les entrées du processus externe.
         C'est une liste de noms de signaux séparée par des virgules. Pour chaque nom de signal, un nombre de bits
diff --git a/src/main/resources/lang/lang_fr_ref.xml b/src/main/resources/lang/lang_fr_ref.xml
index 8996f74dd..b2fe40f69 100644
--- a/src/main/resources/lang/lang_fr_ref.xml
+++ b/src/main/resources/lang/lang_fr_ref.xml
@@ -1418,6 +1418,7 @@ In the file howTo.md you can find more details about translations.
     <string name="key_applicationType_Generic">Generic</string>
     <string name="key_applicationType_GHDL">GHDL</string>
     <string name="key_applicationType_IVERILOG">IVerilog</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_externalInputs">Inputs</string>
     <string name="key_externalInputs_tt">The inputs of the external process.
         It is a comma-separated list of signal names. For each signal name, a number of bits separated by a colon
@@ -1442,6 +1443,9 @@ In the file howTo.md you can find more details about translations.
         iverilog to simulate
         components defined with Verilog.
     </string>
+    <string name="key_verilogLib">Verilog external code library path</string>
+    <string name="key_verilogLib_tt">Used to configure the dependency library path for Verilog code, which will automatically search for dependency code during simulation
+    </string>
     <string name="key_maxValue">Maximum Value</string>
     <string name="key_maxValue_tt">If a zero is entered, the maximum possible value is used (all bits are one).</string>
     <string name="key_dipDefault">Output is High</string>
diff --git a/src/main/resources/lang/lang_it.xml b/src/main/resources/lang/lang_it.xml
index 9f04c0d01..110b1d09d 100644
--- a/src/main/resources/lang/lang_it.xml
+++ b/src/main/resources/lang/lang_it.xml
@@ -1163,6 +1163,7 @@ In the file howTo.md you can find more details about translations.
     <string name="key_applicationType">Applicazione</string>
     <string name="key_applicationType_tt">Definisce quale applicazione utilizzare.</string>
     <string name="key_applicationType_Generic">Generica</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_externalInputs">Ingressi</string>
     <string name="key_externalInputs_tt">Gli ingressi del processo esterno.
         Questa è una lista di nomi di segnali separati da virgola. Per ogni nome, un numero di bit separato
diff --git a/src/main/resources/lang/lang_it_ref.xml b/src/main/resources/lang/lang_it_ref.xml
index 902022220..3d24c109e 100644
--- a/src/main/resources/lang/lang_it_ref.xml
+++ b/src/main/resources/lang/lang_it_ref.xml
@@ -1212,6 +1212,7 @@ In the file howTo.md you can find more details about translations.
     <string name="key_applicationType">Application</string>
     <string name="key_applicationType_tt">Defines which application to use.</string>
     <string name="key_applicationType_Generic">Generic</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_externalInputs">Inputs</string>
     <string name="key_externalInputs_tt">The inputs of the external process.
         It is a comma-separated list of signal names. For each signal name, a number of bits separated by a colon
@@ -1234,6 +1235,9 @@ In the file howTo.md you can find more details about translations.
     <string name="key_iverilogPath_tt">Path to the Icarus Verilog installation folder. Only necessary if you want to use
         iverilog to simulate
         components defined with Verilog.</string>
+    <string name="key_verilogLib">Verilog external code library path</string>
+    <string name="key_verilogLib_tt">Used to configure the dependency library path for Verilog code, which will automatically search for dependency code during simulation
+    </string>
     <string name="key_maxValue">Maximum Value</string>
     <string name="key_maxValue_tt">If a zero is entered, the maximum possible value is used (all bits are one).</string>
     <string name="key_dipDefault">Output is High</string>
diff --git a/src/main/resources/lang/lang_pt.xml b/src/main/resources/lang/lang_pt.xml
index 2b3c99bc8..57796d7f5 100644
--- a/src/main/resources/lang/lang_pt.xml
+++ b/src/main/resources/lang/lang_pt.xml
@@ -1187,6 +1187,7 @@ In the file howTo.md you can find more details about translations.
   <string name="key_applicationType_Generic">Genérico</string>
   <string name="key_applicationType_GHDL">GHDL</string>
   <string name="key_applicationType_IVERILOG">IVerilog</string>
+  <string name="key_applicationType_Socket">Socket</string>
   <string name="key_externalInputs">Entradas</string>
   <string name="key_externalInputs_tt">Entradas do processo externo.
         Lista de nomes de sinais separados por vírgulas. Após cada nome de sinal, separado por dois-pontos, um número de bits
diff --git a/src/main/resources/lang/lang_pt_ref.xml b/src/main/resources/lang/lang_pt_ref.xml
index 3ab9a376e..ab2769472 100644
--- a/src/main/resources/lang/lang_pt_ref.xml
+++ b/src/main/resources/lang/lang_pt_ref.xml
@@ -1249,6 +1249,7 @@ In the file howTo.md you can find more details about translations.
     <string name="key_applicationType_Generic">Generic</string>
     <string name="key_applicationType_GHDL">GHDL</string>
     <string name="key_applicationType_IVERILOG">IVerilog</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_externalInputs">Inputs</string>
     <string name="key_externalInputs_tt">The inputs of the external process.
         It is a comma-separated list of signal names. For each signal name, a number of bits separated by a colon
@@ -1270,6 +1271,9 @@ In the file howTo.md you can find more details about translations.
         iverilog to simulate
         components defined with Verilog.
     </string>
+    <string name="key_verilogLib">Verilog external code library path</string>
+    <string name="key_verilogLib_tt">Used to configure the dependency library path for Verilog code, which will automatically search for dependency code during simulation
+    </string>
     <string name="key_maxValue">Maximum Value</string>
     <string name="key_maxValue_tt">If a zero is entered, the maximum possible value is used (all bits are one).</string>
     <string name="key_dipDefault">Output is High</string>
diff --git a/src/main/resources/lang/lang_zh.xml b/src/main/resources/lang/lang_zh.xml
index 4c2c5639f..5c357b86f 100644
--- a/src/main/resources/lang/lang_zh.xml
+++ b/src/main/resources/lang/lang_zh.xml
@@ -512,6 +512,7 @@ In the file howTo.md you can find more details about translations.
   <string name="key_applicationType">应用</string>
   <string name="key_applicationType_tt">定义使用哪个应用</string>
   <string name="key_applicationType_Generic">通用</string>
+  <string name="key_applicationType_Socket">Socket</string>
   <string name="key_externalInputs">输入</string>
   <string name="key_externalOutputs">输出</string>
   <string name="key_Code">程序代码</string>
@@ -1709,4 +1710,6 @@ In the file howTo.md you can find more details about translations.
     <string name="key_source_dataField">存储数据</string>
     <string name="err_could_not_load_rom">未能载入 ROM 数据</string>
     <string name="msg_fixesCreated_N">修正: {0}</string>
+    <string name="key_verilogLib">Verilog 代码库路径</string>
+    <string name="key_verilogLib_tt">用于配置verilog代码的依赖库路径，在运行仿真时会自动从这个路径查找依赖代码</string>
 </resources>
diff --git a/src/main/resources/lang/lang_zh_ref.xml b/src/main/resources/lang/lang_zh_ref.xml
index c91ab22a0..fd5e7f86f 100644
--- a/src/main/resources/lang/lang_zh_ref.xml
+++ b/src/main/resources/lang/lang_zh_ref.xml
@@ -1987,6 +1987,7 @@ In the file howTo.md you can find more details about translations.
     <string name="key_activeLow_tt">If selected the output is low if the component is active.</string>
     <string name="key_applicationType_GHDL">GHDL</string>
     <string name="key_applicationType_IVERILOG">IVerilog</string>
+    <string name="key_applicationType_Socket">Socket</string>
     <string name="key_iverilogOptions">IVerilog Options</string>
     <string name="key_iverilogOptions_tt">Options that are used for all processing steps by IVerilog.</string>
     <string name="key_iverilogPath">IVerilog</string>
@@ -2163,4 +2164,7 @@ In the file howTo.md you can find more details about translations.
     <string name="key_source_dataField">stored data</string>
     <string name="err_could_not_load_rom">Could not load ROM data!</string>
     <string name="msg_fixesCreated_N">Fixtures: {0}</string>
+    <string name="key_verilogLib">Verilog external code library path</string>
+    <string name="key_verilogLib_tt">Used to configure the dependency library path for Verilog code, which will automatically search for dependency code during simulation
+    </string>
 </resources>
diff --git a/src/test/java/de/neemann/digital/core/extern/ApplicationVerilogStdIOTest.java b/src/test/java/de/neemann/digital/core/extern/ApplicationVerilogStdIOTest.java
index 3c9b86f4c..0ce50ee34 100644
--- a/src/test/java/de/neemann/digital/core/extern/ApplicationVerilogStdIOTest.java
+++ b/src/test/java/de/neemann/digital/core/extern/ApplicationVerilogStdIOTest.java
@@ -10,11 +10,19 @@
 import de.neemann.digital.core.extern.handler.ProcessInterface;
 import de.neemann.digital.hdl.hgs.Context;
 import junit.framework.TestCase;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.contrib.java.lang.system.EnvironmentVariables;
 
 import java.io.File;
+import java.lang.reflect.Field;
+import java.util.Map;
 
 public class ApplicationVerilogStdIOTest extends TestCase {
 
+
+    @Rule
+    public final EnvironmentVariables environmentVariables = new EnvironmentVariables();
     private class TestApp extends ApplicationVerilogStdIO {
 
         @Override
@@ -93,6 +101,24 @@ public void testEnsureConsistencyIndirect2() {
         assertEquals("y:5", attr.get(Keys.EXTERNAL_OUTPUTS));
     }
 
+    @Test
+    public void testReplaceEnvVars() {
+        String path = "d:\\verilogcode\\lib";
+        String pathAfterReplace = ApplicationVerilogStdIO.replaceEnvVars(path);
+        assertEquals("d:\\\\verilogcode\\\\lib",pathAfterReplace);
+
+        path = "/home/verilogcode/lib";
+        pathAfterReplace = ApplicationVerilogStdIO.replaceEnvVars(path);
+        assertEquals(path,pathAfterReplace);
+
+//        path = "${VERILOG_LIB_PATH}";
+//        environmentVariables.set("VERILOG_LIB_PATH","/home/verilogcode/lib");
+//        pathAfterReplace = ApplicationVerilogStdIO.replaceEnvVars(path);
+//        assertEquals("/home/verilogcode/lib",pathAfterReplace);
+//        environmentVariables.clear("VERILOG_LIB_PATH");
+
+    }
+
     private ElementAttributes extractParameters(String code) {
         TestApp ta = new TestApp();
         ElementAttributes attr = new ElementAttributes();