Sony HB-F900
 | |
| HB-F900 (cream version) and its keyboard in Sony's October 1986 catalogue | |
| Specifications | |
|---|---|
| Manufacturer | Sony |
| Type | MSX2 home computer |
| Released | 1986[1] |
| Intro price | ¥148,000[2] |
| CPU | Z80A[2] |
| Memory | 256 KB RAM, 128 KB VRAM, 192 KB ROM[2] |
| Storage | Two 3.5-inch drives, 720 KB each[1] |
| Display | Yamaha V9938[1] |
| Sound | PSG inside the Yamaha S1985 MSX-Engine[1] |
| Power | 100 V AC, 50/60 Hz[2] |
| Dimensions | 355 × 325 × 76 mm (main unit, width × depth × height)[2] |
| Weight | 5.7 kg (main unit), 1.2 kg (keyboard)[2] |
| OS / Firmware | MSX-BASIC 2.0, Disk BASIC 1.0[3] |
| Model no. | HB-F900 (B black, W cream) |
The Sony HB-F900 is an MSX2 computer that Sony sold in Japan from 1986 at ¥148,000, aimed at the professional market. It is a desk-top unit with a separate keyboard, two 3.5-inch drives, 256 KB of RAM and 128 KB of video RAM.[1][2] With Sony's HBI-F900 AV Creator connected to a video interface socket on its back, it can superimpose its own picture on an external video signal; a DSP board inside the HB-F900 handles that interface and the video and audio outputs.[1][3] It was made in black and in cream, and came with a mouse and the Wordship Japanese word processor on two disks.[1][2]
Specifications
[edit | edit source]| Item | Figure |
|---|---|
| Processor | Z80A (Sharp LH0080A or NEC μPD780C) |
| Chipset | Yamaha S1985 MSX-Engine, with the PSG sound generator inside it |
| Video | Yamaha V9938, 128 KB video RAM |
| RAM | 256 KB memory mapper in slot 3-1 |
| ROM | 192 KB: MSX2 BASIC, Disk BASIC and a JIS level 1 kanji ROM; an 8 KB video utility ROM (SonyVideo1 BASIC) |
| Floppy controller | Western Digital WD2793A-PL |
| Drives | Two 3.5-inch double-density drives, 720 KB each |
| Main unit | 355 × 325 × 76 mm, 5.7 kg |
| Keyboard | 409 × 183 × 32 mm, 1.2 kg |
| Power | 100 V AC, 50/60 Hz |
[2][1][3] The WD2793A-PL can be read on the chip in a photograph of the main board.[4]
Hardware
[edit | edit source]
Inside the case the power supply sits at the back left with its transformer, the speaker at the front left, the DSP board along the back right, and the two drives side by side at the front above the main board.[3][5] The bottom panel of the case comes off and exposes the underside of the main board without removing it.[6]
The address, data and control lines to the cartridge slots pass through buffer chips. On one machine that recognised no cartridge, two of these buffers, SN74LS367s, had failed.[6]
The clock and settings are kept by a GS sealed Ni-Cd cell on the main board, labelled 50 mAh, 2.4 V.[4] When it runs low after a long time unused, the stored settings can be corrupted, giving a coloured start-up screen or a machine that will not reach BASIC.[7]
The HB-F900 shares its chipset (the S1985, the V9938, the WD2793 floppy controller) and its 256 KB of RAM with the European Sony HB-F700, and Sony's documents give the same main unit size, 355 mm wide by 325 mm deep by 76 mm high, for both.[1][2] No service information shows whether any of their boards are the same.
Connections
[edit | edit source]The front panel carries the power switch and lamp, cartridge slot 1, drives A and B, the reset switch, a volume slider, the two joystick ports and the keyboard socket. The rear has the RF channel switch and RF output, composite video and audio outputs, the 8-pin DIN RGB output, the HBI-F900 interface connector, cartridge slot 2, an earth terminal, the printer port, the cassette socket, a 100 V AC outlet and the mains lead.[3][2] The HBI-F900 connects through a 50-pin Centronics cable wired pin to pin; one repairer reports that a Centronics SCSI cable works in its place.[6]
Known faults
[edit | edit source]Owners have reported these faults; the Sony HB-F900 Troubleshooting Guide has the details.
- No cartridge recognised in either slot, traced to two failed SN74LS367 bus buffers.[6]
- Drives answering "Disk Offline".[7][8]
- A red or other coloured start-up screen and no BASIC, from corrupted settings when the backup cell runs low.[7]
- Drives tilted in the front panel, from a bent support bar.[6]
- Superimposing with the HBI-F900 not working, unresolved in the thread that reports it.[8]
Maintenance and repair
[edit | edit source]- Sony HB-F900 General Maintenance
- Sony HB-F900 Troubleshooting Guide
- Sony HB-F900 Capacitor Replacement Guide
Documentation
[edit | edit source]No service manual or schematic for the HB-F900 is known to be available online. The MSX Archive's collection of MSX service manuals has none for it,[9] and owners asking for schematics on the MSX Resource Center forum in 2024 received none.[8] Sony's 12-page catalogue for the HB-F900 and HBI-F900, dated October 1986, is on the Internet Archive and gives the main specifications.[2]
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Sony HB-F900, MSX Resource Center wiki, 7 May 2026—link(accessed 2026-10-21) Community page: an MSX2 for the Japanese professional market that can superimpose its picture on a video signal (genlock) through a video interface connector on the back and a DSP board; used with the HBI-F900 AV Creator; black (B) or cream (W); separate KBD-13 or KBD-13(B) keyboard of HB-F500 design; supplied with a DIN-8 to RGB21 cable, MOS-1 mouse and the Wordship word processor on two disks; 1986; ¥148,000; 256 KB of RAM in slot 3-1; 128 KB VRAM; Yamaha V9938; PSG in the Yamaha S1985 MSX-Engine; two 720 KB 3.5-inch drives, internal speaker, reset button, JIS level 1 kanji ROM; Z80A from Sharp (LH0080A) or NEC (μPD780C); Western Digital WD2793A-PL floppy controller; an 8 KB "Video Utility" ROM with SonyVideo1 BASIC; connections: analogue sound and composite video, RGB (8-pin DIN), keyboard, video interface for the HBI-F900, data recorder, Centronics printer port, two general purpose ports, two cartridge slots, AC power socket and AC plug.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 Sony, HB-F900 / HBI-F900 catalogue, Japan, dated '86.10 (October 1986), Internet Archive item sonyhbf900hbif900, page 12, "HB-F900/HBI-F900の主な仕様" (main specifications), and page 3. In Japanese. HB-F900: Z-80A; ROM 192 KB (MSX2 BASIC, MSX2 Disk BASIC and kanji ROM); main RAM 256 KB; video RAM 128 KB; interfaces: two cartridge slots, video, RGB (8-pin), RF, audio, cassette tape, two joystick ports, printer, AC outlet and 50-pin video I/F; accessories include the mouse, a video cable, a plug adapter, an antenna connector and the Wordship software; main unit 355 mm wide × 325 mm deep × 76 mm high, 5.7 kg; keyboard 409 × 183 × 32 mm, 1.2 kg; power 100 V, 50/60 Hz; price ¥148,000. HBI-F900 AV Creator ¥64,800, 100 V, 27 W. Page 3 shows the front panel: power switch, cartridge slot 1, drives A and B with IN USE lamps, reset button, computer sound slider, controller ports A and B, keyboard socket.
- ↑ 3.0 3.1 3.2 3.3 3.4 HB-F900, USB Secret Base (up-c)—link(accessed 2026-10-21) In Japanese. Specification list (Z80A at 3.57 MHz, 256 KB RAM, 128 KB VRAM with the V9938, JIS level 1 kanji ROM, MSX-JE not fitted, PSG equivalent to the AY-3-8910, two 3.5-inch 2DD drives, two cartridge slots, MSX-BASIC 2.0 and Disk BASIC 1.0) and annotated photographs. Front panel: power switch, power lamp, slot 1, reset switch, drives A and B, volume slider, joystick ports A and B, keyboard connector. Rear panel: RF channel switch, RF output, video output, audio output, RGB output, HBI-F900 interface connector, slot 2, earth terminal, printer connector, data recorder interface, AC outlet (AC 100 V), mains lead. Inside: the power supply section, the speaker, the DSP board (interface to the HBI-F900 and video and audio output), the main board and drives A and B.
- ↑ 4.0 4.1 File:Sony HB-F900 main board.jpg, photograph of the main board of a black HB-F900, uploaded to the MSX Resource Center wiki by Gdx on 20 March 2016. Read from it: Yamaha V9938, Sharp LH0080 Z80, WD2793A-PL floppy controller, and at the left a GS sealed Ni-Cd battery labelled 50 mAh, 2.4 V (Japan Storage Battery Co.). The values of the electrolytic capacitors cannot be read in the photograph.
- ↑ USB Secret Base, "HB-F900", annotated photograph of the inside (http://usbsecretbase.michikusa.jp/hb-f900/index.html, retrieved 2026-10-21). Read from it: the power supply at the back left with its transformer, heatsinks and a large reservoir capacitor; the speaker at the front left; the DSP board along the back right, with many small electrolytics; the two drives side by side at the front, over the main board.
- ↑ 6.0 6.1 6.2 6.3 6.4 O MSX Sony HB-F900 que não aceitava cartuchos...– Alexandre Souza, 15 August 2018—link(accessed 2026-10-21) In Portuguese. Repair of an HB-F900 that recognised no cartridge in either the front or the rear slot. The HB-F900 and the HBI-F900 are joined by a 50-pin Centronics cable wired pin to pin, so a Centronics SCSI cable works. The bottom panel comes off to expose the underside of the main board without removing it. The main board is held by six screws plus connectors; removing it completely also means unsoldering a grey coaxial cable to the video output board, so note its connections. The drives are held by four screws at the back; the bar that supports them is commonly bent so the drives sit tilted at the front, and can be removed and straightened; the drives do not use a belt. In his experience the power supply does not normally need recapping. All address, data and control signals to the slots are buffered; with an oscilloscope he found two signals present on the inputs of the buffers and missing on the outputs, and replaced a pair of SN74LS367 chips, fitting them in sockets; he blames a faulty cartridge.
- ↑ 7.0 7.1 7.2 Instructions to repair or replace HB-F900 Floppy Drive(s)?, May 2021—link(accessed 2026-10-21) Thread by BitSquad: the HB-F900's drive answers "Disk Offline" to FILES. sdsnatcher73, 12 May 2021: a PC drive converted for MSX with the READY signal works; without it, on an HB-F700, the machine freezes when booting into BASIC until a formatted disk is inserted, while games and DOS boot normally. Manuel, 12 May 2021: Sony machines use the WD2793; if the HB-F900's drive is like the HB-G900P's, it has a standard 34-pin Shugart connector. BitSquad, 13 May 2021: the machine then started with a red screen and did not reach BASIC; Manuel: the stored settings were corrupt, cured with SHIFT+F1, SET TITLE "", SET SCREEN and a reset, which worked; Grauw: the start-up colour is a setting, SET TITLE "",1 gives the blue screen; sdsnatcher73: this happens when the backup battery is low after long disuse and the clock memory is corrupted. BitSquad, 15 May 2021: a new Mitsumi drive lit its LED continuously until the cable was turned round, then answered "Disk Offline"; Manuel: a continuously lit LED means the cable is upside down; meits: bridge pins 33 and 34 to provide READY, without touching pin 32, and one drive is enough; jltursan: on the cable, swap lines 10 and 12 and join 33 and 34 to make a PC drive into drive A with a constant READY. sdsnatcher73, 16 May 2021: a red screen with "@ D" under the logo means the backup battery is dying; remove it. Accumulator, 10 March 2023: a Mitsumi D359T5 worked in an HB-F700.
- ↑ 8.0 8.1 8.2 HB-F900 + HBI-F900 troubleshooting, May 2024—link(accessed 2026-10-21) Post by drone, 11 May 2024: an HB-F900 with an HBI-F900; cartridges work but the drives do not; the HB-F900 can change HBI-F900 settings from BASIC, but video from the HBI-F900 input does not come through for superimposing; he asks for any service documents or schematics, including Japanese ones, and none are posted.
- ↑ Index of /pub/msx/docs/service_manuals, MSX Archive—link(accessed 2026-10-21) Directory of MSX service manuals; it holds Sony manuals for the HB-101, HB-D30, HB-D50, HB-F1XD, HB-F9P, HB-F500, HB-F700P, HB-G900AP, HB-G900P, HB-K30, HB-M232, HB-M512 and others, and none for the HB-F900.