diff --git a/demos/sdcard/apple1_sdcard/apple1_sdcard.ino b/demos/sdcard/apple1_sdcard/apple1_sdcard.ino
index a652002..6c95db1 100644
--- a/demos/sdcard/apple1_sdcard/apple1_sdcard.ino
+++ b/demos/sdcard/apple1_sdcard/apple1_sdcard.ino
@@ -175,6 +175,7 @@ const int CMD_DEL   = 11;
 const int CMD_LS    = 12;
 const int CMD_CD    = 13;
 const int CMD_MKDIR = 14;
+const int CMD_PWD   = 19;
 const int CMD_RMDIR = 15;
 
 const int ERR_RESPONSE = 255;
@@ -705,10 +706,6 @@ void comando_mkdir() {
 // **************************************************************************************
 // **************************************************************************************
 
-void send_cd_path() {
-  send_string_to_cpu(cd_path);
-}
-
 void comando_cd() {
   Serial.println(F("command CD received from CPU"));
 
@@ -722,24 +719,35 @@ void comando_cd() {
 
   // CD without arguments
   if(filename[0] == 0) {
-    // does nothing simply prints the path    
-    send_cd_path();
+    // ok response
+    send_byte_to_cpu(OK_RESPONSE);
     return;
   }
 
+  // CD ..
+  if(filename[0] == '.' && filename[1] == '.' && filename[2] == 0) {  
+    strcpy(filename, cd_path);
+    for(int t=strlen(filename)-1;t>=1;t--) {
+      int c = filename[t];
+      filename[t] = 0;
+      if(c == '/') break;        
+    }
+  }
+
   // CD /
   if(filename[0] == '/' && filename[1] == 0) {
     // changes to the root directory
     if(SD.chdir()) {
       // set root working directory
       strcpy(cd_path, filename);      
-      send_cd_path();
       Serial.print(F("dir changed to:"));
       Serial.println(cd_path);
+      send_byte_to_cpu(OK_RESPONSE);
       return;      
     }   
     else {
       Serial.println(F("error changing dir"));
+      send_byte_to_cpu(ERR_RESPONSE);
       send_string_to_cpu(CANT_CD_DIR);
       return;
     }
@@ -748,28 +756,32 @@ void comando_cd() {
   // CD dirname  
   if(SD.chdir(filename)) {
     // update working directory
-    if(filename[0] == '/') {
-      // replace cwd
-      strcpy(cd_path, filename);      
+    if(filename[0] == '/') {       
+      strcpy(cd_path, filename);     // path is absolute, replace cwd   
     }
     else {
-      // append to cwd
+      // path is relative, append to cwd
+      if(cd_path[0] == '/' && cd_path[1] == 0) {        
+        cd_path[0] = 0;  // avoid the double slash ("//DIR") when cwd is root 
+      }
       sprintf(tmp, "%s/%s", cd_path, filename);
       strcpy(cd_path, tmp);
     }
     
-    // print working directory 
-    send_cd_path();
+    
     Serial.print(F("dir changed to:"));
     Serial.println(cd_path);    
+    send_byte_to_cpu(OK_RESPONSE);
     return;
   } 
 
   // errors 
+
+  send_byte_to_cpu(ERR_RESPONSE);
   
   // check if the directory exists
   if(!SD.exists(filename)) {
-    Serial.println(F("dir not found"));
+    Serial.println(F("dir not found"));    
     send_string_to_cpu(DIR_NOT_FOUND);
     return;
   }
@@ -779,15 +791,26 @@ void comando_cd() {
   myFile.close();
   
   if(!isDir) {            
-    Serial.println(F("not a directory"));
+    Serial.println(F("not a directory"));    
     send_string_to_cpu(NOT_A_DIRECTORY);    
   }
   else {
-    Serial.println(F("error changing dir"));
+    Serial.println(F("error changing dir"));    
     send_string_to_cpu(CANT_CD_DIR);    
   }
 }
 
+// **************************************************************************************
+// **************************************************************************************
+// ********************************* @CMD_PWD *******************************************
+// **************************************************************************************
+// **************************************************************************************
+
+void comando_pwd() {
+  Serial.println(F("command PWD received from CPU"));
+  send_string_to_cpu(cd_path);
+}
+
 // **************************************************************************************
 // **************************************************************************************
 // ********************************* LOOP  **********************************************
@@ -800,12 +823,15 @@ void loop() {
   int data = receive_byte_from_cpu();
   if(TIMEOUT) return;
 
+  unsigned long start_time = millis();
+
        if(data == CMD_READ)  comando_read();      
   else if(data == CMD_WRITE) comando_write();      
   else if(data == CMD_DEL)   comando_del();    
   else if(data == CMD_RMDIR) comando_rmdir();    
   else if(data == CMD_MKDIR) comando_mkdir();     
   else if(data == CMD_CD)    comando_cd();      
+  else if(data == CMD_PWD)   comando_pwd();      
   else if(data == CMD_DIR)   comando_dir(data);    
   else if(data == CMD_LS)    comando_dir(data);    
   else {
@@ -813,6 +839,9 @@ void loop() {
     Serial.print(data);
     Serial.println(F(" received"));
   }
+
+  Serial.print(F("command processing time: "));
+  Serial.println(millis() - start_time);
   
   if(TIMEOUT) Serial.println(F("TIMEOUT during command"));    
 }
diff --git a/demos/sdcard/cmd_dir.h b/demos/sdcard/cmd_dir.h
index d485be5..59f2a59 100644
--- a/demos/sdcard/cmd_dir.h
+++ b/demos/sdcard/cmd_dir.h
@@ -6,5 +6,5 @@ void comando_dir(byte cmd) {
    send_string_to_MCU(filename);
    if(TIMEOUT) return;
 
-   print_string_response();   
+   print_string_response_brk();   
 }
diff --git a/demos/sdcard/cmd_dump.h b/demos/sdcard/cmd_dump.h
index 6a5df21..055c73f 100644
--- a/demos/sdcard/cmd_dump.h
+++ b/demos/sdcard/cmd_dump.h
@@ -30,11 +30,13 @@ void comando_dump() {
 
    // get file bytes   
    byte row = 0;
+   byte print_on = 1;
    for(word t=0;t!=tmpword;t++) {
       byte data = receive_byte_from_MCU();
       if(TIMEOUT) return;
 
       if(!(t>=start_address && t<=end_address)) continue;
+      if(!print_on) continue;
 
       if(row == 0) {
          woz_putc('\r');
@@ -50,7 +52,7 @@ void comando_dump() {
       
       if(apple1_readkey()) {
          woz_puts("*BRK*\r");
-         break;
+         print_on = 0;
       }
    }
 }
diff --git a/demos/sdcard/cmd_type.h b/demos/sdcard/cmd_type.h
index 572c879..df90035 100644
--- a/demos/sdcard/cmd_type.h
+++ b/demos/sdcard/cmd_type.h
@@ -22,14 +22,15 @@ void comando_type() {
    receive_word_from_mcu();
    if(TIMEOUT) return;
 
-   // get file bytes   
+   // get file bytes
+   byte print_on = 1;   
    for(word t=0;t!=tmpword;t++) {
       byte data = receive_byte_from_MCU();
       if(TIMEOUT) return;
-      woz_putc(data);
+      if(print_on) woz_putc(data);
       if(apple1_readkey()) {
          woz_puts("*BRK*\r");
-         break;
+         print_on = 0;
       }
    }
 }
diff --git a/demos/sdcard/m.bat b/demos/sdcard/m.bat
index fbba712..cce5ee4 100644
--- a/demos/sdcard/m.bat
+++ b/demos/sdcard/m.bat
@@ -1 +1,2 @@
-call ..\..\tools\build sdcard
\ No newline at end of file
+call ..\..\tools\build sdcard
+copy out\sdcard.prg ..\..\..\apple1-emu\software\sdcard.prg /y
diff --git a/demos/sdcard/sdcard.c b/demos/sdcard/sdcard.c
index bf59203..cd04003 100644
--- a/demos/sdcard/sdcard.c
+++ b/demos/sdcard/sdcard.c
@@ -114,9 +114,20 @@ void print_string_response() {
       if(TIMEOUT) break;
       if(data == 0) break;  // string terminator
       else woz_putc(data);
+   }
+}
+
+// print a string sent by the MCU, breakable via keyboard
+void print_string_response_brk() {
+   byte print_on = 1;
+   while(1) {
+      byte data = receive_byte_from_MCU();
+      if(TIMEOUT) break;
+      if(data == 0) break;  // string terminator
+      if(print_on) woz_putc(data);
       if(apple1_readkey()) {
-         woz_puts("*BRK*\r");
-         break;
+         woz_puts("*BRK*\r");         
+         print_on = 0;
       }      
    }
 }