diff --git a/basic/source/inc/iosys.hxx b/basic/source/inc/iosys.hxx
index 4cc0f9b3314e..7134e7b6855f 100644
--- a/basic/source/inc/iosys.hxx
+++ b/basic/source/inc/iosys.hxx
@@ -45,10 +45,11 @@ class SvStream;
 #define SBSTRM_APPEND   0x0008
 #define SBSTRM_BINARY   0x0010
 
-class SbiStream {
+class SbiStream
+{
     SvStream* pStrm;
     sal_uIntPtr  nExpandOnWriteTo;  // during writing access expand the stream to this size
-    ByteString aLine;
+    rtl::OString aLine;
     sal_uIntPtr  nLine;
     short  nLen;                    // buffer length
     short  nMode;
@@ -59,11 +60,11 @@ class SbiStream {
 public:
     SbiStream();
    ~SbiStream();
-    SbError Open( short, const ByteString&, short, short, short );
+    SbError Open( short, const rtl::OString&, short, short, short );
     SbError Close();
-    SbError Read( ByteString&, sal_uInt16 = 0, bool bForceReadingPerByte=false );
+    SbError Read(rtl::OString&, sal_uInt16 = 0, bool bForceReadingPerByte=false);
     SbError Read( char& );
-    SbError Write( const ByteString&, sal_uInt16 = 0 );
+    SbError Write( const rtl::OString&, sal_uInt16 = 0 );
 
     bool IsText() const     { return (nMode & SBSTRM_BINARY) == 0; }
     bool IsRandom() const   { return (nMode & SBSTRM_RANDOM) != 0; }
@@ -78,28 +79,30 @@ public:
     SvStream* GetStrm()                { return pStrm;          }
 };
 
-class SbiIoSystem {
+class SbiIoSystem
+{
     SbiStream* pChan[ CHANNELS ];
-    ByteString  aPrompt;
-    ByteString  aIn, aOut;
+    rtl::OString aPrompt;
+    rtl::OString aIn;
+    rtl::OString aOut;
     short     nChan;
     SbError   nError;
-    void      ReadCon( ByteString& );
-    void      WriteCon( const ByteString& );
+    void      ReadCon(rtl::OString&);
+    void      WriteCon(const rtl::OString&);
 public:
     SbiIoSystem();
    ~SbiIoSystem();
     SbError GetError();
     void  Shutdown();
-    void  SetPrompt( const ByteString& r ) { aPrompt = r; }
+    void  SetPrompt(const rtl::OString& r) { aPrompt = r; }
     void  SetChannel( short n  )       { nChan = n;   }
     short GetChannel() const           { return nChan;}
     void  ResetChannel()               { nChan = 0;   }
-    void  Open( short, const ByteString&, short, short, short );
+    void  Open( short, const rtl::OString&, short, short, short );
     void  Close();
-    void  Read( ByteString&, short = 0 );
+    void  Read(rtl::OString&, short = 0);
     char  Read();
-    void  Write( const ByteString&, short = 0 );
+    void  Write(const rtl::OString&, short = 0);
     short NextChannel();
     // 0 == bad channel or no SvStream (nChannel=0..CHANNELS-1)
     SbiStream* GetStream( short nChannel ) const;
diff --git a/basic/source/runtime/iosys.cxx b/basic/source/runtime/iosys.cxx
index 79dcb0ef8b2d..63ae9feb65fd 100644
--- a/basic/source/runtime/iosys.cxx
+++ b/basic/source/runtime/iosys.cxx
@@ -562,7 +562,7 @@ void    UCBStream::SetSize( sal_uIntPtr nSize )
 
 
 SbError SbiStream::Open
-( short nCh, const ByteString& rName, short nStrmMode, short nFlags, short nL )
+( short nCh, const rtl::OString& rName, short nStrmMode, short nFlags, short nL )
 {
     nMode   = nFlags;
     nLen    = nL;
@@ -571,7 +571,7 @@ SbError SbiStream::Open
     nExpandOnWriteTo = 0;
     if( ( nStrmMode & ( STREAM_READ|STREAM_WRITE ) ) == STREAM_READ )
         nStrmMode |= STREAM_NOCREATE;
-    String aStr( rName, osl_getThreadTextEncoding() );
+    String aStr(rtl::OStringToOUString(rName, osl_getThreadTextEncoding()));
     String aNameStr = getFullPath( aStr );
 
     if( hasUno() )
@@ -642,14 +642,12 @@ SbError SbiStream::Close()
     return nError;
 }
 
-SbError SbiStream::Read( ByteString& rBuf, sal_uInt16 n, bool bForceReadingPerByte )
+SbError SbiStream::Read(rtl::OString& rBuf, sal_uInt16 n, bool bForceReadingPerByte)
 {
     nExpandOnWriteTo = 0;
     if( !bForceReadingPerByte && IsText() )
     {
-        rtl::OString aBuffer;
-        pStrm->ReadLine(aBuffer);
-        rBuf = aBuffer;
+        pStrm->ReadLine(rBuf);
         nLine++;
     }
     else
@@ -673,13 +671,13 @@ SbError SbiStream::Read( ByteString& rBuf, sal_uInt16 n, bool bForceReadingPerBy
 SbError SbiStream::Read( char& ch )
 {
     nExpandOnWriteTo = 0;
-    if( !aLine.Len() )
+    if (aLine.isEmpty())
     {
         Read( aLine, 0 );
-        aLine += '\n';
+        aLine = aLine + rtl::OString('\n');
     }
-    ch = aLine.GetBuffer()[0];
-    aLine.Erase( 0, 1 );
+    ch = aLine[0];
+    aLine = aLine.copy(1);
     return nError;
 }
 
@@ -705,7 +703,7 @@ void SbiStream::ExpandFile()
 
 namespace
 {
-    void WriteLines(SvStream &rStream, const ByteString& rStr)
+    void WriteLines(SvStream &rStream, const rtl::OString& rStr)
     {
         ByteString aStr( rStr );
         aStr.ConvertLineEnd( rStream.GetLineDelimiter() );
@@ -714,7 +712,7 @@ namespace
     }
 }
 
-SbError SbiStream::Write( const ByteString& rBuf, sal_uInt16 n )
+SbError SbiStream::Write( const rtl::OString& rBuf, sal_uInt16 n )
 {
     ExpandFile();
     if( IsAppend() )
@@ -722,25 +720,26 @@ SbError SbiStream::Write( const ByteString& rBuf, sal_uInt16 n )
 
     if( IsText() )
     {
-        aLine += rBuf;
+        aLine = aLine + rBuf;
         // Get it out, if the end is an LF, but strip CRLF before,
         // because the SvStrm adds a CRLF!
-        sal_uInt16 nLineLen = aLine.Len();
-        if( nLineLen && aLine.GetBuffer()[ --nLineLen ] == 0x0A )
+        sal_Int32 nLineLen = aLine.getLength();
+        if (nLineLen && aLine[--nLineLen] == 0x0A)
         {
-            aLine.Erase( nLineLen );
-            if( nLineLen && aLine.GetBuffer()[ --nLineLen ] == 0x0D )
-                aLine.Erase( nLineLen );
+            aLine = aLine.copy(0, nLineLen);
+            if (nLineLen && aLine[--nLineLen] == 0x0D)
+                aLine = aLine.copy(0, nLineLen);
             WriteLines(*pStrm, aLine);
-            aLine.Erase();
+            aLine = rtl::OString();
         }
     }
     else
     {
-        if( !n ) n = nLen;
+        if( !n )
+            n = nLen;
         if( !n )
             return nError = SbERR_BAD_RECORD_LENGTH;
-        pStrm->Write( rBuf.GetBuffer(), n );
+        pStrm->Write(rBuf.getStr(), n);
         MapError();
     }
     return nError;
@@ -774,8 +773,7 @@ SbError SbiIoSystem::GetError()
     return n;
 }
 
-void SbiIoSystem::Open
-    ( short nCh, const ByteString& rName, short nMode, short nFlags, short nLen )
+void SbiIoSystem::Open(short nCh, const rtl::OString& rName, short nMode, short nFlags, short nLen)
 {
     nError = 0;
     if( nCh >= CHANNELS || !nCh )
@@ -824,9 +822,9 @@ void SbiIoSystem::Shutdown()
     }
     nChan = 0;
     // anything left to PRINT?
-    if( aOut.Len() )
+    if( !aOut.isEmpty() )
     {
-        String aOutStr( aOut, osl_getThreadTextEncoding() );
+        rtl::OUString aOutStr(rtl::OStringToOUString(aOut, osl_getThreadTextEncoding()));
 #if defined GCC
         Window* pParent = Application::GetDefDialogParent();
         MessBox( pParent, WinBits( WB_OK ), String(), aOutStr ).Execute();
@@ -834,11 +832,11 @@ void SbiIoSystem::Shutdown()
         MessBox( GetpApp()->GetDefDialogParent(), WinBits( WB_OK ), String(), aOutStr ).Execute();
 #endif
     }
-    aOut.Erase();
+    aOut = rtl::OString();
 }
 
 
-void SbiIoSystem::Read( ByteString& rBuf, short n )
+void SbiIoSystem::Read(rtl::OString& rBuf, short n)
 {
     if( !nChan )
         ReadCon( rBuf );
@@ -853,13 +851,13 @@ char SbiIoSystem::Read()
     char ch = ' ';
     if( !nChan )
     {
-        if( !aIn.Len() )
+        if( aIn.isEmpty() )
         {
             ReadCon( aIn );
-            aIn += '\n';
+            aIn = aIn + rtl::OString('\n');
         }
-        ch = aIn.GetBuffer()[0];
-        aIn.Erase( 0, 1 );
+        ch = aIn[0];
+        aIn = aIn.copy(1);
     }
     else if( !pChan[ nChan ] )
         nError = SbERR_BAD_CHANNEL;
@@ -868,7 +866,7 @@ char SbiIoSystem::Read()
     return ch;
 }
 
-void SbiIoSystem::Write( const ByteString& rBuf, short n )
+void SbiIoSystem::Write(const rtl::OString& rBuf, short n)
 {
     if( !nChan )
         WriteCon( rBuf );
@@ -921,7 +919,7 @@ void SbiIoSystem::CloseAll(void)
 ***************************************************************************/
 
 
-void SbiIoSystem::ReadCon( ByteString& rIn )
+void SbiIoSystem::ReadCon(rtl::OString& rIn)
 {
     String aPromptStr( aPrompt, osl_getThreadTextEncoding() );
     SbiInputDialog aDlg( NULL, aPromptStr );
@@ -929,27 +927,29 @@ void SbiIoSystem::ReadCon( ByteString& rIn )
         rIn = rtl::OUStringToOString(aDlg.GetInput(), osl_getThreadTextEncoding());
     else
         nError = SbERR_USER_ABORT;
-    aPrompt.Erase();
+    aPrompt = rtl::OString();
 }
 
 // output of a MessageBox, if theres a CR in the console-buffer
 
-void SbiIoSystem::WriteCon( const ByteString& rText )
+void SbiIoSystem::WriteCon(const rtl::OString& rText)
 {
     aOut += rText;
-    sal_uInt16 n1 = aOut.Search( '\n' );
-    sal_uInt16 n2 = aOut.Search( '\r' );
-    if( n1 != STRING_NOTFOUND || n2 != STRING_NOTFOUND )
+    sal_Int32 n1 = aOut.indexOf('\n');
+    sal_Int32 n2 = aOut.indexOf('\r');
+    if( n1 != -1 || n2 != -1 )
     {
-        if( n1 == STRING_NOTFOUND ) n1 = n2;
-        else
-        if( n2 == STRING_NOTFOUND ) n2 = n1;
-        if( n1 > n2 ) n1 = n2;
-        ByteString s( aOut.Copy( 0, n1 ) );
-        aOut.Erase( 0, n1 );
-        while( aOut.GetBuffer()[0] == '\n' || aOut.GetBuffer()[0] == '\r' )
-            aOut.Erase( 0, 1 );
-        String aStr( s, osl_getThreadTextEncoding() );
+        if( n1 == -1 )
+            n1 = n2;
+        else if( n2 == -1 )
+            n2 = n1;
+        if( n1 > n2 )
+            n1 = n2;
+        rtl::OString s(aOut.copy(0, n1));
+        aOut = aOut.copy(n1);
+        while (aOut[0] == '\n' || aOut[0] == '\r')
+            aOut = aOut.copy(1);
+        String aStr(rtl::OStringToOUString(s, osl_getThreadTextEncoding()));
         {
             SolarMutexGuard aSolarGuard;
             if( !MessBox( GetpApp()->GetDefDialogParent(),
diff --git a/basic/source/runtime/methods1.cxx b/basic/source/runtime/methods1.cxx
index af2cfbc24f7b..04a21d59af73 100644
--- a/basic/source/runtime/methods1.cxx
+++ b/basic/source/runtime/methods1.cxx
@@ -3209,7 +3209,7 @@ RTLFUNC(Input)
         return;
     }
 
-    ByteString aByteBuffer;
+    rtl::OString aByteBuffer;
     SbError err = pSbStrm->Read( aByteBuffer, nByteCount, true );
     if( !err )
         err = pIosys->GetError();
@@ -3219,7 +3219,7 @@ RTLFUNC(Input)
         StarBASIC::Error( err );
         return;
     }
-    rPar.Get(0)->PutString( String( aByteBuffer, osl_getThreadTextEncoding() ) );
+    rPar.Get(0)->PutString(rtl::OStringToOUString(aByteBuffer, osl_getThreadTextEncoding()));
 }
 
 RTLFUNC(Me)
diff --git a/basic/source/runtime/step0.cxx b/basic/source/runtime/step0.cxx
index 7268d3d0e558..b5591fd1f424 100644
--- a/basic/source/runtime/step0.cxx
+++ b/basic/source/runtime/step0.cxx
@@ -1175,11 +1175,11 @@ void SbiRuntime::StepINPUT()
 
 void SbiRuntime::StepLINPUT()
 {
-    ByteString aInput;
+    rtl::OString aInput;
     pIosys->Read( aInput );
     Error( pIosys->GetError() );
     SbxVariableRef p = PopVar();
-    p->PutString( String( aInput, osl_getThreadTextEncoding() ) );
+    p->PutString(rtl::OStringToOUString(aInput, osl_getThreadTextEncoding()));
 }
 
 // end of program