Sony HBD-50
This page was last modified 23:55, 26 August 2019 by Rderooy. Based on work by Mars2000you and Zeilemaker54 and others.


The HBD-50 is a single sided 360kB 3.5" floppy disk drive with interface adapter, released by Sony in 1984. It supports up to two drives. It was sometimes advertised as having a storage capacity of 500Kbytes, but in reality after formatting this is reduced to 360kB.

This drive was also released by 2 other companies: see Yamaha FD-01 and Toshiba HX-F100. However Philips had a few samples too!

The interface includes a ROM with version 1 of the Disk BASIC commands.

Part of the interface electronics are in the cartridge, and part are in the drive enclosure. As such the cartridge and drive enclosure must be used together and cannot be used with a different enclosure or interface unit.


  • The Disk ROM with driver version SNYJX121 has a bug in the DSKFMT routine. After a FORMAT there will be 3kB less capacity then there should be. This issue is documented in the Dutch language MSX Club Magazine 32 on page 8-9, including a small program to recover the lost 3kB.
  • The Disk ROM with driver version SNYJX130 does not have the bug of the SNYJ121 but has another bug in the DSKFMT routine. The second FAT copy is written incorrectly, but this is less of a problem. As soon as a file is written to disk, the second FAT copy is updated and becomes consistent.
Brand Sony
Type HBD-50
Year 1984
Region JP, Europe
Official price DE: 1098 DM
JP: ¥89,800
UK: £349.95
Package content HBD-50 interface
HBD-50 drive
Data cable
Operating instructions
Emulation ROM dumped, and emulated


Sony HBD-50 interface
Sony HBD-50 disk drive + interface
Sony HBD-50 disk drive
Sony HBD-50 disk drive (back)
Sony HBD-50 disk drive (underside)