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diff --git a/decoders/mfm/__init__.py b/decoders/mfm/__init__.py
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+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2023 Eric Anderson <ejona86@gmail.com>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, see <http://www.gnu.org/licenses/>.
+##
+
+'''
+FM and MFM is a combined clock/data encoding used on floppy disks. The bit
+stream requires a stacked decoder to detect a format-specific sync pattern to
+determine the byte boundaries and to separate the clock and data.
+
+The necessary sampling frequency is often 8x the data rate, so sampling at
+least at 16x the data rate is recommended.
+
+There are various interfaces with floppy disk drives, but most are very similar
+in principal to the Shugart interface. They use open-drain signals with events
+signaled with falling edges. Decoding the data is mostly done with the Read
+Data (RDATA, RD) and Write Data (WDATA, WD) lines, with optional help from
+Index (IDX), Write Gate (WG), and other lines. The "Enable low" and "Enable
+high" channels are most directly used by setting one of the channels to WG to
+enable decoding only when writing or reading. But they can also be used with
+other signals like Disk Select, Step, Track 0, and Side Select.
+'''
+
+from .pd import Decoder