diff --git a/ba/bacnv.cpp b/ba/bacnv.cpp
index 3f8c0be21..1bec72fd2 100755
--- a/ba/bacnv.cpp
+++ b/ba/bacnv.cpp
@@ -8,10 +8,17 @@
 #include <tabutil.h>
 #include <urldefid.h>
 #include <utility.h>
+#include <extcdecl.h>
+#if XVT_OS == XVT_OS_WIN
+#include <direct.h>
+#define RMDIR _rmdir
+#else               
+#define RMDIR rmdir
+#endif
 
 #include <rmov.h>
 
-#define usage "Errore - uso : bacnv [1|2|3] ditta"
+#define usage "Errore - uso : bacnv [1|2|3|4] ditta"
 
 class TConversione_archivi : public TApplication
 {
@@ -33,6 +40,7 @@ public:
   bool patch_uff(TRectype & rec, const char * const fnames[]);
   bool collate(TRectype & rec, const char * f1, const char * f2);
   void patch_com(void);
+  void zero_770(void);
 
   TConversione_archivi() : _oldditta(0), _codditta(0), _error(0) {}
 };
@@ -92,6 +100,9 @@ bool TConversione_archivi::menu(MENU_TAG)
   case 3:
     if (_codditta == 0)
       patch_com();
+  case 4:
+    if (_codditta == 0)
+      zero_770();
   default:
     break;  
   }
@@ -247,6 +258,37 @@ void TConversione_archivi::patch_com()
   }                                                    
 }
 
+void TConversione_archivi::zero_770()
+{ 
+  for (int i = LF_BASE ; i <= LF_DETH; i++)
+  {
+    TDir d;      
+    
+    d.get(i, _lock, _nordir, _sysdirop); 
+    d.eod() = 0L;             
+    d.eox() = 0L;
+    d.put(i,  _nordir, _sysdirop);  
+  }      
+  TToken_string files;
+  
+  if (fexist(format("%scom/770", __ptprf)))
+  {       
+    files.format("%scom/770/%s", __ptprf, "*");   
+    list_files(files);
+    for (const char * s = files.get(); s != NULL; s = files.get())
+      remove(s);               
+    RMDIR(format("%scom/770", __ptprf)); 
+  }
+  if (fexist(format("%s770", __ptprf)))
+  {       
+    files.format("%s770/%s", __ptprf, "*");   
+    list_files(files);
+    for (const char * s = files.get(); s != NULL; s = files.get())
+      remove(s);               
+    RMDIR(format("%s770", __ptprf)); 
+  }
+}
+
 ///////////////////////////////////////////////////////////
 // Programma di conversione archivi speciale
 ///////////////////////////////////////////////////////////
@@ -255,7 +297,7 @@ int main(int argc,char** argv)
 {
   const int r = (argc > 1) ? atoi(argv[1]) : 0;
   
-  if (r <= 0 || r > 3)
+  if (r <= 0 || r > 4)
   {
     error_box(usage);
     return 100;