Merritt method

Method

An overwrite session consists of a lead-in of random write patterns, followed by patterns 2-3, executed in a random order, and a lead-out of one more random patterns followed by 00000000 and another random.

The drive is written to for all the passes even though the table below only shows the bit patterns for the passes that are specifically targeted at each encoding scheme. The end result should obscure any data on the drive so that only the most advanced physical scanning (e.g. using a magnetic force microscope) of the drive is likely to be able to recover any data.

The series of patterns is as follows:

Merritt overwrite method

Pass	Data Written		Pattern written to disk for targeted encoding scheme
	In Binary notation	In Hex notation	(1,7) RLL	(2,7) RLL	MFM
1	(Random)	(Random)
2	00000000, 10100000, 00100000
3	10100000, 00000000, 00100000, 00000000
4	(Random)	(Random)
5	00000000, Random	00000000, (Random)