The M2637 series, which began shipping in August 1993, was Fujitsu’s first series of 2.5-inch magnetic disk units. These products marked Fujitsu’s entry into the mobile market and became the foundation of the company’s future compact magnetic disk units. In terms of form factor, the M2637 offered a 17-millimeter profile that was slightly thinner than the 19-millimeter profile that was common at the time. Despite the thinner profile, it housed three disks with a total storage capacity of 240 MB.
To support as many applications as possible, the M2637 came with two standard interfaces: a SCSI-2 interface and an ATA interface. Fujitsu, in this model, established zone bit recording*1 with an embedded servo*2 and one MPU control,*3 technologies that would become standard in small magnetic disk units and be applied to future units.
*1. Zone bit recording: a recording method that divides the disk’s inner and outer circumference into zones and varies the recording frequency for each zone.
*2. Embedded servo: a format that embeds the recorded track’s position in the data.
*3. One MPU control: A method in which one MPU controls both the data and the hardware.