diff --git a/tools/mem_read.py b/tools/mem_read.py
index f0e676e2f..0e30fddb4 100755
--- a/tools/mem_read.py
+++ b/tools/mem_read.py
@@ -7,6 +7,14 @@ from trezorlib.transport_hid import HidTransport
 import binascii
 import sys
 
+# usage examples
+# read entire bootloader: ./mem_read.py 8000000 8000
+# read initial stack pointer: ./mem_read.py 8000000 4
+# an entire bootloader can be later disassembled with:
+# arm-none-eabi-objdump -D -b binary -m arm -M force-thumb memory.dat
+# note that in order for this to work, your trezor device must
+# be running a firmware that was built with debug link enabled
+
 def main():
     # List all connected TREZORs on USB
     devices = HidTransport.enumerate()
@@ -24,9 +32,16 @@ def main():
     client = TrezorClient(transport)
     debug = DebugLink(debug_transport)
 
-    mem = debug.memory_read(int(sys.argv[1],16), int(sys.argv[2],16))
+    arg1 = int(sys.argv[1], 16)
+    arg2 = int(sys.argv[2], 16)
+    step = 0x400 if arg2 >= 0x400 else arg2
+
     f = open('memory.dat', 'w')
-    f.write(mem)
+
+    for addr in range(arg1, arg1 + arg2, step):
+      mem = debug.memory_read(addr, step)
+      f.write(mem)
+
     f.close()
 
     client.close()