diff --git a/firmware/FIRMWARE.ZX2 b/firmware/FIRMWARE.ZX2
index 94c084a..5baf190 100644
Binary files a/firmware/FIRMWARE.ZX2 and b/firmware/FIRMWARE.ZX2 differ
diff --git a/firmware/FIRMWARE.ZXD b/firmware/FIRMWARE.ZXD
index bdc48f0..398b4e1 100644
Binary files a/firmware/FIRMWARE.ZXD and b/firmware/FIRMWARE.ZXD differ
diff --git a/firmware/firmware.asm b/firmware/firmware.asm
index b028c05..cc08ab0 100644
--- a/firmware/firmware.asm
+++ b/firmware/firmware.asm
@@ -1068,8 +1068,20 @@ conti   di
         jr      z, ccon0
 runbit  ld      b, h
         call    calbit
-
+      IF  version=2 OR version=3
+        push    hl
+        wreg    flash_cs, 0     ; activamos spi, enviando un 0
+        wreg    flash_spi, 6    ; envío write enable
+        wreg    flash_cs, 1     ; desactivamos spi, enviando un 1
+        wreg    flash_cs, 0     ; activamos spi, enviando un 0
+        wreg    flash_spi, $c5  ; envío wrear
+        out     (c), a
+        wreg    flash_cs, 1     ; desactivamos spi, enviando un 1
+        dec     b
+        pop     hl
+      ELSE
         ld      bc, zxuno_port
+      ENDIF
         ld      e, core_addr
         out     (c), e
         inc     b
@@ -3173,11 +3185,10 @@ calbi1    ld      a, b        ;1-69
           jr      c, calbi2   ;<35 c n
           ld      b, a        ;>=35 nc n-35
 calbi2    ld      hl, $0240
-          ret     z
+          jr      z, calbi4
           ld      de, $0740
 calbi3    add     hl, de
           djnz    calbi3
-          ret
         ELSE
 calbi1    ld      a, b        ;1-40
           sub     20
@@ -3188,8 +3199,13 @@ calbi2    ld      hl, $fec0
           ld      de, $0c40
 calbi3    add     hl, de
           djnz    calbi3
-          ret
+          dec     a
         ENDIF
+calbi4    rlca
+          sbc     a, a
+          inc     a
+          ld      (alto highb+1), a
+          ret
       ENDIF
     ENDIF
 
diff --git a/firmware/strings.asm b/firmware/strings.asm
index 9ddb651..77a4507 100644
--- a/firmware/strings.asm
+++ b/firmware/strings.asm
@@ -4,8 +4,8 @@ cad1    defb    'http://zxuno.speccy.org', 0
       ELSE
 cad1    defb    'http://zxdos.forofpga.es', 0
       ENDIF
-        defb    'ZX-Uno BIOS v0.83', 0
-        defb    'Copyleft ', 127, ' 2020 ZX-Uno Team', 0
+        defb    'ZX-Uno BIOS v0.84', 0
+        defb    'Copyleft ', 127, ' 2021 ZX-Uno Team', 0
         defb    'Processor: Z80 3.5MHz', 0
         defb    'Memory:    '
 cadmem  defb    '512K Ok', 0
@@ -41,7 +41,7 @@ cad8    defb    $10, '                         ', $10, '              ', $10, 0
 cad9    defb    $14, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11
         defb    $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $18, $11
         defb    $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $15, 0
-        defb    '   BIOS v0.83    ', $7f, '2020 ZX-Uno Team', 0
+        defb    '   BIOS v0.84    ', $7f, '2021 ZX-Uno Team', 0
       ELSE
         defb    'Press <Edit> to Setup',0
         defb    '      <Break> Boot Menu', 0
@@ -72,7 +72,7 @@ cad8    defb    $10, '                              ', $10, 0
 cad9    defb    $14, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11
         defb    $11, $11, $11, $11
         defb    $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $11, $15, 0
-        defb    ' BIOS v0.83 ', $7f, '2020 ZX1 Team', 0
+        defb    ' BIOS v0.84 ', $7f, '2021 ZX1 Team', 0
         defs    $66
       ENDIF
 cad10   defb    'Hardware tests', 0