【Mitsubishi Electric】 M4863 Hard Disk Unit

This was a sealed hard disk unit with a maximum memory capacity of 10MB. It employed a 5.25-inch (13.3cm) magnetic disk and was announced by Mitsubishi Electric in 1981. It was designed for compactness and low price, and had outstanding reliability and maintainability. It was used in office computers, personal computers and various types of terminals.

This unit had the following features:

  • There were 3 models with a capacity of 3.3MB, 6.7MB and 10MB, which could be selected to suit the application.
  • Mounting was easy because it had the same external dimensions, mounting dimensions and DC power supply as mini flexible disk units.
  • It enabled high-speed access, with an average seek time of 75ms and average access time of 8.3ms, and achieved high-speed transfer at 5.0MB/s.
  • A simple, high-precision, high-reliability mechanism was realized using a positioning mechanism employing a stepping motor, and a direct spindle mechanism using a DC brushless motor.
  • It could be used without being affected by adverse dust conditions, due to its completely sealed structure and its use of a replaceable breath filter.
  • It was equipped with an industry standard interface, and could be easily connected to a controller.
Main Specifications of M4863 Hard Disk Unit
Unit memory capacity 3.33MB(model 1),6.66MB(model 2)
10.00MB(model 3)
Track capacity 10,417byte
Bit density 7,900bit/inch
Track density 256track/inch
Data transfer speed 5.0Mbit/s
Positioning time Min. 18ms,Max. 160ms,Average 75ms
Rotational delay Average 8.33ms
Rotation speed 3,600rpm
External dimensions(Width x Height x Depth) 149.4mm×85.8mm×208mm
Weight 2.5kg

M4863 Hard Disk Unit