Sony HBD-50
This page was last modified 16:37, 17 April 2021 by Mars2000you. Based on work by Msxholder and Rderooy and others.



The HBD-50 is a single sided 360kB 3.5" floppy disk drive with interface adapter, released by Sony in late 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.

The controller installed in the FDD is MB8847 (NMOS 4-bit single-chip microprocessor). The installed drive is the Sony MFD-33V (1DD), also used in the internal FDD unit HBD-100 added to the HB-701 computer or integated in the HB-701FD machine.

This drive was also released by 3 other companies: see Sanyo MFD-35, Toshiba HX-F100 and Yamaha FD-01. However Philips had a few samples too!

Sony released a specific version for Germany, using the reference HBD-50D. The only difference seems to be the German translation of warning texts on the drive and the interface. These texts are in Japanese or English on the other versions.

The unit comes in a box of 160 × 67 × 260 mm with a weight of 2.7 kilograms, with an internal power supply of 100 V AC and 23 Watt (Japanese model) or 220 V AC and 24 Watt (European model).

The interface includes a ROM with version 1 of the Disk BASIC commands. The controller is based on the WD2793-02 chip.

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
Model HBD-50
Year 1984-12
Region JP, Europe
Launch price DE: 1098 DM
IT: L. 950,000
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 European box and content
Sony HBD-50 disk drive
Sony HBD-50 disk drive (back)
Sony HBD-50 European box
Sony HBD-50 interface
Sony HBD-50 disk drive (EU underside)
Sony HBD-50 Japanese box and main content
Sony HBD-50 JP interface and drive (underside)
Sony HBD-50 Japanese box and full content
Sony HBD-50 disk drive + interface
Sony HBD-50 Japanese label
Sony HBD-50 European label


Sony HBD-50D disk drive
Sony HBD-50D interface
Sony HBD-50D interface (underside)
Sony HBD-50D disk drive
Sony HBD-50D label