What Does Modified Frequency Modulation (MFM) Mean?
Modified frequency modulation (MFM) is a method of encoding digital data on magnetic media. MFM was used with early hardware, including Control Program for Microcomputers (CP/M), IBM compatible PCs and Amiga PCs.
MFM was used on 3.5-inch and 5.25-inch disks, or floppys, with data transfer rates (DTR) of 250 to 500 kbps, as well as MFM ST-506 hard disks up to five Mbps. MFM is now obsolete, with the exception of 1.44 MB floppy disks.
Because MFM had two times the capacity of previous frequency modulation (FM) encoding, it was also known as “double density.”
Techopedia Explains Modified Frequency Modulation (MFM)
As an enhanced frequency modulation (FM) encoding scheme, MFM reduces the number of flux reversals incorporated for clock pulses, allowing for greater data density. When compared to FM, MFM doubles linear bit density and decreases lineal flux reversal density without increasing recorded magnetic density. Additionally, the recording code uses solely synchronized clock pulses if data bits are not available.
