diff --git a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_if_disk.h b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_if_disk.h
index de72895..a5a4d0a 100644
--- a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_if_disk.h
+++ b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_if_disk.h
@@ -26,7 +26,7 @@
  */
 
 /*
- * $Id: wdc_if_disk.h,v 1.10 2013/05/04 15:40:14 olivleh1 Exp $
+ * $Id: wdc_if_disk.h,v 1.11 2013/05/09 12:30:25 olivleh1 Exp $
  */
 
 #ifndef WDC_IF_DISK_H_
@@ -56,6 +56,8 @@ t_drv_write_block      drv_write_block;
 t_drv_read_multiblock  drv_read_multiblock;
 t_drv_write_multiblock drv_write_multiblock;
 
+#define wdc_number_of_disks() 1
+
 #define WDC_BLOCKLEN 512
 
 #endif /* WDC_IF_DISK_H_ */
\ No newline at end of file
diff --git a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_if_p8000.c b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_if_p8000.c
index 64ec847..aa134d3 100644
--- a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_if_p8000.c
+++ b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_if_p8000.c
@@ -26,7 +26,7 @@
  */
 
 /*
- * $Id: wdc_if_p8000.c,v 1.16 2013/05/04 15:40:15 olivleh1 Exp $
+ * $Id: wdc_if_p8000.c,v 1.17 2013/05/09 12:30:25 olivleh1 Exp $
  */
 
 #include "wdc_config.h"
@@ -38,11 +38,11 @@
 
 void wdc_wait_for_reset ()
 {
-    while ( isset_info_reset() ) {
-        port_data_set ( DATA_CLEAR );
-        port_info_set ( INFO_CLEAR );
-        wdc_set_initialized ( 1 );
-    }
+    port_data_set ( DATA_CLEAR );
+    port_info_set ( INFO_CLEAR );
+    wdc_set_initialized ( 1 );
+
+    while ( isset_info_reset() ) {}
 }
 
 uint8_t wdc_read_data_from_p8k ( uint8_t *buffer, uint16_t count, uint8_t wdc_status )
diff --git a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_main.c b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_main.c
index af134d3..bbd9342 100644
--- a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_main.c
+++ b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_main.c
@@ -27,7 +27,7 @@
 
 
 /*
- * $Id: wdc_main.c,v 1.35 2013/05/09 00:16:04 olivleh1 Exp $
+ * $Id: wdc_main.c,v 1.36 2013/05/09 12:30:25 olivleh1 Exp $
  *
  */
 
@@ -165,6 +165,22 @@ main ( void )
                 } else {
                     wdc_send_error();
                 }
+                /* if the specified drive exceeds the number of drives, no drive commands are allowed */
+            } else if ( cmd_buffer[1] >= wdc_number_of_disks()
+                        && ( cmd_buffer[0] == CMD_RD_SECTOR
+                             || cmd_buffer[0] == CMD_FMTRD_TRACK
+                             || cmd_buffer[0] == CMD_RD_BLOCK
+                             || cmd_buffer[0] == CMD_WR_BLOCK
+                             || cmd_buffer[0] == CMD_FMTBTT_TRACK
+                             || cmd_buffer[0] == CMD_VER_TRACK
+                             || ( cmd_buffer[0] == CMD_RD_BTTAB && !wdc_get_btt_cleared() )
+                           )
+                      ) {
+                if ( cmd_buffer[0] == CMD_RD_BTTAB ) {
+                    wdc_send_errorcode ( ERR_BTT_INVALID );
+                } else {
+                    wdc_send_errorcode ( ERR_DRIVE_NOT_READY );
+                }
             } else {
 
                 switch ( cmd_buffer[0] ) {
diff --git a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_main.h b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_main.h
index 9954c46..32a2327 100644
--- a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_main.h
+++ b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_main.h
@@ -26,7 +26,7 @@
  */
 
 /*
- * $Id: wdc_main.h,v 1.14 2013/05/04 15:40:15 olivleh1 Exp $
+ * $Id: wdc_main.h,v 1.15 2013/05/09 12:30:25 olivleh1 Exp $
  */
 
 #ifndef MAIN_H_
@@ -59,8 +59,10 @@
 #define CMD_ST_PARBTT         0xc2              /* store Parameter block and BTT on hard disk       */
 
 #define ERR_STANDARD          0x01
+#define ERR_DRIVE_NOT_READY   0x03
 #define ERR_SECT_N_ON_SURFACE 0x0A
 #define ERR_BTT_FULL          0x16
+#define ERR_BTT_INVALID       0x18
 #define ERR_NO_DRIVE_READY    0x27
 #define ERR_CYL0_NOT_READABLE 0x31
 
diff --git a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_par.c b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_par.c
index bb099fa..d4c0d6e 100644
--- a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_par.c
+++ b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_par.c
@@ -26,7 +26,7 @@
  */
 
 /*
- * $Id: wdc_par.c,v 1.9 2013/05/04 15:40:15 olivleh1 Exp $
+ * $Id: wdc_par.c,v 1.10 2013/05/09 12:30:25 olivleh1 Exp $
  */
 
 #include <avr/pgmspace.h>
@@ -104,6 +104,7 @@ const uint8_t
 
 uint8_t valid_disk = 1;
 uint8_t initialized;
+uint8_t btt_cleared = 0;
 
 void wdc_read_par_table ( uint8_t *buffer, uint16_t count )
 {
@@ -146,6 +147,7 @@ void wdc_del_wdc_btt ()
     }
 
     par_table[122 + POS_PAR_WDC_BTT] = 0xff;
+    btt_cleared = 1;
 }
 
 void wdc_read_wdc_btt ( uint8_t *buffer, uint16_t count )
@@ -277,4 +279,9 @@ void wdc_set_initialized ( uint8_t num )
 uint8_t wdc_get_initialized ()
 {
     return initialized;
+}
+
+uint8_t wdc_get_btt_cleared ()
+{
+    return btt_cleared;
 }
\ No newline at end of file
diff --git a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_par.h b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_par.h
index a1d2a4c..b765685 100644
--- a/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_par.h
+++ b/P8000_WDC_Emulator/P8000_WDC_Emulator/wdc_par.h
@@ -26,7 +26,7 @@
  */
 
 /*
- * $Id: wdc_par.h,v 1.6 2013/05/04 15:40:15 olivleh1 Exp $
+ * $Id: wdc_par.h,v 1.7 2013/05/09 12:30:25 olivleh1 Exp $
  */
 
 #ifndef WDC_PAR_H_
@@ -52,6 +52,7 @@ extern void     wdc_set_no_disk ();
 extern uint8_t  wdc_get_num_of_drvs ();
 extern void     wdc_set_initialized ( uint8_t num );
 extern uint8_t  wdc_get_initialized ();
+extern uint8_t  wdc_get_btt_cleared ();
 
 #define POS_PAR_VERSION     0           /* defines at which position in the PAR table the WDC version string starts */
 #define POS_PAR_WDC_PAR     8           /* defines at which position in the PAR table the WDC parameter section starts */