Sony HB-G900P
This page was last modified 01:55, 26 September 2023 by Mars2000you. Based on work by Manuel and Rderooy and others.



The HB-G900P is the adaptation of the HB-F900 for the European market. This computer supports superimposition with genlock.

The special video I/F connector on the back can be used to connect the Sony HBI-G900P Videotizer, which enables you to actually record the superimposed video and can also perform digitization. Both devices were used in the Mir space station.

In addition a second internal disk drive could be added in the form of the HBD-G900.

It has a built in Video Utility ROM: Laser Disc control (using the RS-232C interface) and an MSX-BASIC extension to show large texts on the screen (useful with superimposing). Note that SonyLDP BASIC is not compatible with the Pioneer P-BASIC.

This model was a special computer aimed at the professional market. The keyboard is separate from the main unit. This model is only available in white color. The keyboard reference is KBD-12P.

Comes with a single disk (please see the manual): MSX-DOS/Character Font System and Font Disk.

Included manuals: Operating Instructions, A Guide to MSX-BASIC version 2.0, MSX-BASIC Version 2.0 Programming Reference Manual, Reference Chart, Video Utility, A Guide to RS-232C Communication.

The HB-G900P was later replaced by the more advanced model HB-G900AP.

Brand Sony
Model HB-G900P
Year 1986
Region Europe
Launch price
RAM 64kB in slot 3
VRAM 128kB
Media MSX cartridges, 2DD floppy disks
Video Yamaha V9938
Audio PSG (AY-3-8910)
Chipset none (separate IC's)
Keyboard layout QWERTY wih a "£" key + numeric keypad
Extras One or two 720kB 3.5" floppy disk drives, superimposition capacity, reset button, RS-232C interface, software, SonyLDP BASIC
Emulation ROMs dumped and emulated except for the superimpose and genlock functions


Sony HB-G900P
HB-G900P with Videotizer
Sony HB-G900P back
Sony HB-G900P & Videotizer rear


The HB-G900P is a MSX2 with a Z80A from Sharp (LH0080A) and without MSX-Engine. The floppy disk controller chip is the CXD-1032Q (Sony).

The architecture is with standard components. The RAM is 64 kb in primary slot 3. The RS-232C has an 2kb SRAM for buffer and variables.(See service manual)

The optional AV creator HBI-900 interface has been replaced by the Videotizer (HBI-G900), a simplified interface to digitize images and do superimposing for the European market.

Slot Map

Slot 0-0 Slot 0-1 Slot 0-2 Slot 0-3 Slot 1 Slot 2 Slot 3
Page C000h~FFFFh Cartridge
Slot 1
Slot 2
Page 8000h~BFFFh
Page 4000h~7FFFh Main-ROM Disk ROM RS-232C Firmware
Page 0000h~3FFFh Sub-ROM