diff --git a/src/base/abci/abc.c b/src/base/abci/abc.c
index e019d8104..3729dcf3b 100644
--- a/src/base/abci/abc.c
+++ b/src/base/abci/abc.c
@@ -33969,11 +33969,11 @@ usage:
 ***********************************************************************/
 int Abc_CommandAbc9WriteSim( Abc_Frame_t * pAbc, int argc, char ** argv )
 {
-    int c, fOutputs = 0, fTrans = 0, fVerbose = 0;
+    int c, fOutputs = 0, fTrans = 0, fBool = 0, fVerbose = 0;
     char ** pArgvNew;
     int nArgcNew;
     Extra_UtilGetoptReset();
-    while ( ( c = Extra_UtilGetopt( argc, argv, "otvh" ) ) != EOF )
+    while ( ( c = Extra_UtilGetopt( argc, argv, "otbvh" ) ) != EOF )
     {
         switch ( c )
         {
@@ -33983,6 +33983,9 @@ int Abc_CommandAbc9WriteSim( Abc_Frame_t * pAbc, int argc, char ** argv )
         case 't':
             fTrans ^= 1;
             break;
+        case 'b':
+            fBool ^= 1;
+            break;
         case 'v':
             fVerbose ^= 1;
             break;
@@ -34017,46 +34020,63 @@ int Abc_CommandAbc9WriteSim( Abc_Frame_t * pAbc, int argc, char ** argv )
     if ( fOutputs )
     {
         Vec_Wrd_t * vTemp;
+        int nWords = Vec_WrdSize(pAbc->pGia->vSimsPo) / Gia_ManCoNum(pAbc->pGia);
         assert( Vec_WrdSize(pAbc->pGia->vSimsPo) % Gia_ManCoNum(pAbc->pGia) == 0 );
         if ( fTrans )
         {
             int nSize = Vec_WrdSize(pAbc->pGia->vSimsPo);
-            int nWords = Vec_WrdSize(pAbc->pGia->vSimsPo) / Gia_ManCoNum(pAbc->pGia);
             Vec_WrdFillExtra( pAbc->pGia->vSimsPo, nWords * 64 * ((Gia_ManCoNum(pAbc->pGia) + 63)/64), 0 );
             vTemp = Vec_WrdStart( Vec_WrdSize(pAbc->pGia->vSimsPo) );
             Extra_BitMatrixTransposeP( pAbc->pGia->vSimsPo, nWords, vTemp, (Gia_ManCoNum(pAbc->pGia) + 63)/64 );
-            Vec_WrdDumpHex( pArgvNew[0], vTemp, (Gia_ManCoNum(pAbc->pGia) + 63)/64, 1 );
+            if ( fBool )
+                Vec_WrdDumpBool( pArgvNew[0], vTemp, (Gia_ManCoNum(pAbc->pGia) + 63)/64, Gia_ManCoNum(pAbc->pGia), 1, 1 );
+            else
+                Vec_WrdDumpHex( pArgvNew[0], vTemp, (Gia_ManCoNum(pAbc->pGia) + 63)/64, 1 );
             Vec_WrdShrink( pAbc->pGia->vSimsPo, nSize );
             Vec_WrdFree( vTemp );
         }
         else
-            Vec_WrdDumpHex( pArgvNew[0], pAbc->pGia->vSimsPo, Vec_WrdSize(pAbc->pGia->vSimsPo) / Gia_ManCoNum(pAbc->pGia), 1 );
+        {
+            if ( fBool )
+                Vec_WrdDumpBool( pArgvNew[0], pAbc->pGia->vSimsPo, nWords, Gia_ManCoNum(pAbc->pGia), 1, 1 );
+            else
+                Vec_WrdDumpHex( pArgvNew[0], pAbc->pGia->vSimsPo, nWords, 1 );
+        }
     }
     else
     {
         Vec_Wrd_t * vTemp;
+        int nWords = Vec_WrdSize(pAbc->pGia->vSimsPi) / Gia_ManCiNum(pAbc->pGia);
         assert( Vec_WrdSize(pAbc->pGia->vSimsPi) % Gia_ManCiNum(pAbc->pGia) == 0 );
         if ( fTrans )
         {
             int nSize = Vec_WrdSize(pAbc->pGia->vSimsPi);
-            int nWords = Vec_WrdSize(pAbc->pGia->vSimsPi) / Gia_ManCiNum(pAbc->pGia);
             Vec_WrdFillExtra( pAbc->pGia->vSimsPi, nWords * 64 * ((Gia_ManCiNum(pAbc->pGia) + 63)/64), 0 );
             vTemp = Vec_WrdStart( Vec_WrdSize(pAbc->pGia->vSimsPi) );
             Extra_BitMatrixTransposeP( pAbc->pGia->vSimsPi, nWords, vTemp, (Gia_ManCiNum(pAbc->pGia) + 63)/64 );
-            Vec_WrdDumpHex( pArgvNew[0], vTemp, (Gia_ManCiNum(pAbc->pGia) + 63)/64, 1 );
+            if ( fBool )
+                Vec_WrdDumpBool( pArgvNew[0], vTemp, (Gia_ManCiNum(pAbc->pGia) + 63)/64, Gia_ManCiNum(pAbc->pGia), 1, 1 );
+            else
+                Vec_WrdDumpHex( pArgvNew[0], vTemp, (Gia_ManCiNum(pAbc->pGia) + 63)/64, 1 );
             Vec_WrdShrink( pAbc->pGia->vSimsPi, nSize );
             Vec_WrdFree( vTemp );
         }
         else
-            Vec_WrdDumpHex( pArgvNew[0], pAbc->pGia->vSimsPi, Vec_WrdSize(pAbc->pGia->vSimsPi) / Gia_ManCiNum(pAbc->pGia), 1 );
+        {
+            if ( fBool )
+                Vec_WrdDumpBool( pArgvNew[0], pAbc->pGia->vSimsPi, nWords, Gia_ManCiNum(pAbc->pGia), 1, 1 );
+            else
+                Vec_WrdDumpHex( pArgvNew[0], pAbc->pGia->vSimsPi, nWords, 1 );
+        }
     }
     return 0;
 
 usage:
-    Abc_Print( -2, "usage: &sim_write [-otvh] <file>\n" );
+    Abc_Print( -2, "usage: &sim_write [-otbvh] <file>\n" );
     Abc_Print( -2, "\t         writes simulation patterns into a file\n" );
     Abc_Print( -2, "\t-o     : toggle writing output information [default = %s]\n", fOutputs? "yes": "no" );
     Abc_Print( -2, "\t-t     : toggle transposing the simulation information [default = %s]\n", fTrans? "yes": "no" );
+    Abc_Print( -2, "\t-b     : toggle dumping in boolean vs hexadecimal notation [default = %s]\n", fBool? "yes": "no" );
     Abc_Print( -2, "\t-v     : toggle printing verbose information [default = %s]\n", fVerbose? "yes": "no" );
     Abc_Print( -2, "\t-h     : print the command usage\n");
     Abc_Print( -2, "\t<file> : file to store the simulation info\n");
diff --git a/src/misc/vec/vecWrd.h b/src/misc/vec/vecWrd.h
index fdbb18666..e10ce8c56 100644
--- a/src/misc/vec/vecWrd.h
+++ b/src/misc/vec/vecWrd.h
@@ -1284,7 +1284,46 @@ static inline void Vec_WrdAppend( Vec_Wrd_t * vVec1, Vec_Wrd_t * vVec2 )
   SeeAlso     []
 
 ***********************************************************************/
-static inline void Gia_ManSimPatWriteOne( FILE * pFile, word * pSim, int nWords )
+static inline void Vec_WrdDumpBoolOne( FILE * pFile, word * pSim, int nBits, int fReverse )
+{
+    int k;
+    if ( fReverse )
+        for ( k = nBits-1; k >= 0; k-- )
+            fprintf( pFile, "%d", (pSim[k/64] >> (k%64)) & 1 );
+    else
+        for ( k = 0; k < nBits; k++ )
+            fprintf( pFile, "%d", (pSim[k/64] >> (k%64)) & 1 );
+    fprintf( pFile, "\n" );
+}
+static inline void Vec_WrdDumpBool( char * pFileName, Vec_Wrd_t * p, int nWords, int nBits, int fReverse, int fVerbose )
+{
+    int i, nNodes = Vec_WrdSize(p) / nWords;
+    FILE * pFile = fopen( pFileName, "wb" );
+    if ( pFile == NULL )
+    {
+        printf( "Cannot open file \"%s\" for writing.\n", pFileName );
+        return;
+    }
+    assert( Vec_WrdSize(p) % nWords == 0 );
+    for ( i = 0; i < nNodes; i++ )
+        Vec_WrdDumpBoolOne( pFile, Vec_WrdEntryP(p, i*nWords), nBits, fReverse );
+    fclose( pFile );
+    if ( fVerbose )
+        printf( "Written %d bits of simulation data for %d objects into file \"%s\".\n", nBits, Vec_WrdSize(p)/nWords, pFileName );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Vec_WrdDumpHexOne( FILE * pFile, word * pSim, int nWords )
 {
     int k, Digit, nDigits = nWords*16;
     for ( k = 0; k < nDigits; k++ )
@@ -1302,7 +1341,7 @@ static inline void Vec_WrdPrintHex( Vec_Wrd_t * p, int nWords )
     int i, nNodes = Vec_WrdSize(p) / nWords;
     assert( Vec_WrdSize(p) % nWords == 0 );
     for ( i = 0; i < nNodes; i++ )
-        Gia_ManSimPatWriteOne( stdout, Vec_WrdEntryP(p, i*nWords), nWords );
+        Vec_WrdDumpHexOne( stdout, Vec_WrdEntryP(p, i*nWords), nWords );
 }
 static inline void Vec_WrdDumpHex( char * pFileName, Vec_Wrd_t * p, int nWords, int fVerbose )
 {
@@ -1315,7 +1354,7 @@ static inline void Vec_WrdDumpHex( char * pFileName, Vec_Wrd_t * p, int nWords,
     }
     assert( Vec_WrdSize(p) % nWords == 0 );
     for ( i = 0; i < nNodes; i++ )
-        Gia_ManSimPatWriteOne( pFile, Vec_WrdEntryP(p, i*nWords), nWords );
+        Vec_WrdDumpHexOne( pFile, Vec_WrdEntryP(p, i*nWords), nWords );
     fclose( pFile );
     if ( fVerbose )
         printf( "Written %d words of simulation data for %d objects into file \"%s\".\n", nWords, Vec_WrdSize(p)/nWords, pFileName );