diff --git a/src/devices/disk.py b/src/devices/disk.py
index f24adc7..fa0db18 100644
--- a/src/devices/disk.py
+++ b/src/devices/disk.py
@@ -1,4 +1,5 @@
 import sys
+import utils.misc as misc
 
 # System can have multple Disks (Floppy, Harddisks)
 # Disks can have multiple Drives (0, 1, ...)
@@ -10,6 +11,7 @@ def __init__(self, type, drives):
         self.selected_drive = -1
         self.numdrives = len(drives)
         self.drives = []
+        self.write_ena = False
         for i, fs in enumerate(drives):
             self.drives.append(Drive(i, fs))
 
@@ -43,13 +45,13 @@ def select_drive(self, i):
         assert self.selected_drive in [1, 2, 3, 4, 5, 6, 7]
 
 
+    # bad name, also used in Drive
     def readbyte(self):
         return self.drive.readbyte()
 
-
-    def write(self, byte):
-        print('write not supported')
-        sys.exit()
+    # bad name, also used in Drive
+    def writebyte(self, byte):
+        self.drive.writebyte(byte)
 
 
     def step(self, stepdir):
@@ -93,6 +95,10 @@ def __init__(self, driveno, fs): #
         self.current_byte = 0
 
 
+    def dump(self, track):
+        misc.hexdump(self.data[track], 32, 511)
+
+
     def istrack0(self):
         return self.current_track == 0
 
@@ -126,6 +132,17 @@ def readbyte(self):
         return self.data[track][byte]
 
 
+    def writebyte(self, value):
+        track = self.current_track
+        byte = self.current_byte - 3 # TODO don't understand this offset
+        d = self.data[track][byte]
+
+        assert 0 <= track < self.tracks
+        assert 0 <= byte < self.bytes_per_track, byte
+        self.data[track][byte] = value
+        self.current_byte = (self.current_byte + 1) % self.bytes_per_track
+
+
     def gettrackno(self):
         return self.current_track
 
@@ -166,6 +183,10 @@ def data_in(self) -> int:
         return val
 
 
+    def data_out(self, value):
+        self.disk.writebyte(value)
+
+
     def control1(self, val):
         drive = val & 0x7f
         side = val >> 7
@@ -189,7 +210,9 @@ def control2(self, val):
         if val & 0x20: # Step
             self.disk.step(stepdir)
         if val & 0x80:
-            self.disk.write()
+            self.disk.write_ena = True
+        else:
+            self.disk.write_ena = False
 
 
     def status(self):
diff --git a/src/devices/z80io.py b/src/devices/z80io.py
index f265388..d5f0219 100644
--- a/src/devices/z80io.py
+++ b/src/devices/z80io.py
@@ -222,6 +222,7 @@ def handle_disk_out_0b(self, val):
 
     def handle_disk_out_09(self, val):
         self.print(f'IO out - floppy (data) - (0x{val:02x})')
+        self.floppy.data_out(val)
 
 
     def handle_disk_in_0a(self):
diff --git a/src/emulator.py b/src/emulator.py
index a572b80..181bfb1 100644
--- a/src/emulator.py
+++ b/src/emulator.py
@@ -74,7 +74,7 @@ def kbd_input(self):
         kc = self.kc
         if self.key.kbhit():
             ch = ord(self.key.getch())
-            # if 32 <= ch < 127:
+            # if misc.isprintable(ch):
             #     print(f'{chr(ch)}')
             # else:
             #     print(f'{ch}')
@@ -87,10 +87,11 @@ def kbd_input(self):
                 self.int38(kc.okey(k))
             elif ch == 8224: # opt-t
                 args.decode = not args.decode
-            elif ch == 170: # opt-a FDs
-                self.ros.index()
-                self.ros.file()
-                self.ros.disk()
+            elif ch == 170: # opt-a misc debug FDs, floppy dump
+                self.io.floppy.disk.drives[1].dump(0)
+                # self.ros.index()
+                # self.ros.file()
+                # self.ros.disk()
             # Q1 Keyboard input below
             elif ch == kc.ikey("HEX"):
                 self.int38(kc.okey("HEX"))
diff --git a/src/filesys.py b/src/filesys.py
index 0007d0f..0427f75 100644
--- a/src/filesys.py
+++ b/src/filesys.py
@@ -107,7 +107,9 @@ def rawrecord(self, track, offset, data):
         i = len(data)
         d[offset + i + 0] = cksum
         d[offset + i + 1] = 0x10
-        return offset + i + 2
+        d[offset + i + 2] = 0x00 # needed by write
+        d[offset + i + 3] = 0x00 # needed by write
+        return offset + i + 4
 
 
     #
diff --git a/src/utils/misc.py b/src/utils/misc.py
new file mode 100644
index 0000000..e5ee164
--- /dev/null
+++ b/src/utils/misc.py
@@ -0,0 +1,30 @@
+
+
+
+def isprintable(value : int):
+    return 32 <= value < 127
+
+
+def ascii(value : int):
+    if isprintable(value):
+        return chr(value)
+    return '.'
+
+
+def hexdump(lst, width, maxbytes):
+    hexdp = '0000: '
+    ascii = ''
+    l = 0
+    for i, d in enumerate(lst):
+        if i > maxbytes:
+            break
+        hexdp += f'{d:02x} '
+        ascii += chr(d) if 32 <= d < 127 else '.'
+        l += 1
+        if l == width:
+            print(hexdp, ascii)
+            hexdp = f'{i+1:04x}: '
+            ascii = ''
+            l = 0
+    if len(ascii) != width:
+        print(hexdp, ascii)