JVC HC-90
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| The Victor HC-90(T), one of the two later versions with 256 KB of RAM and the V9958 video chip | |
| Specifications | |
|---|---|
| Manufacturer | Victor Company of Japan (JVC) |
| Type | MSX2 personal computer |
| Released | 10 March 1986[1] |
| Intro price | From ¥168,000[1] |
| CPU | Z80A (Sharp LH0080A, later NEC µPD780C-1), 3.58 MHz; Hitachi HD64180, 6.144 MHz, in turbo mode |
| Memory | 64 KB RAM (256 KB in the (V) and (T) versions), 128 KB video RAM |
| Storage | One 3.5-inch 720 KB floppy drive; one cartridge slot |
| Display | Yamaha V9938 (V9958 in the (V) and (T) versions) |
| Sound | Yamaha YM2149 (PSG) |
| Power | 100 V AC ±10%, 50/60 Hz |
| OS / Firmware | — |
| Model no. | HC-90, HC-90(A), HC-90(B), HC-90(V), HC-90(T) |
The JVC HC-90 is an MSX2 computer made by the Victor Company of Japan and sold in Japan under the Victor name from 1986. It has two processors: a Z80A for normal MSX use and a Hitachi HD64180 (a Z180) at 6.144 MHz for a turbo mode, selected one at a time by a switch on the front. It also has a built-in superimposer and frame grabber, and was sold with video titling software. The keyboard is separate and plugs into the back. The HC-95 is the same machine with two floppy drives in place of one.[1]
Versions
[edit | edit source]| Version | RAM | Video chip | Outputs | Front switches | Keyboard connector |
|---|---|---|---|---|---|
| HC-90 | 64 KB | V9938 | RF | Colour enhancer | 20-pin |
| HC-90(A) | 64 KB | V9938 | RF | Colour enhancer | 20-pin |
| HC-90(B) | 64 KB | V9938 | RF | Colour enhancer; search switch added | 20-pin |
| HC-90(V) | 256 KB with memory mapper | V9958 | Composite video and mono audio in place of RF | Through switch in place of the enhancer; search switch | D-sub |
| HC-90(T) | 256 KB with memory mapper | V9958 | Composite video and mono audio | Through switch; search switch | D-sub |
[1] The HC-90(A) changed the floppy controller board and the main board slightly. The (B) changed the floppy controller board, the analog circuit and the power supply. The (V) was sold mainly to professional users with titling software, and the (T) differs from it in the floppy drive, a shield cover and a few other details.[1] The MSX Resource Center's table gives the V9958 to both the (V) and the (T); its infobox gives it to the (T) only.[1]
Victor's parts change list for the HC-90 and HC-95 shows the processor on the digital main board changed from a Sharp LH0080A to an NEC µPD780C-1, the 74LS393 counter at IC1015 changed to a 74HC393, the two system ROMs at IC1040 and IC1052 changed from issue 00B to 00E, and EMI filters added.[2]
Hardware
[edit | edit source]_main_board.jpg)
The machine is built from several boards. Victor's circuit diagrams cover four of them:[3]
- Digital main board, EA-1020A in the first HC-90 and HC-95 and EA-1021A in the (A) versions: the two processors, the YM2149 sound chip, the 8255 peripheral interface, an 8251 serial chip and an 8253 timer for the RS-232C port, the Ricoh RP5C01 clock chip with its backup battery, and the printer, cassette, joystick and keyboard interfaces.[3]
- Analog main board, EA-5020A: the V9938 video chip, its four µPD41464C-12 video RAM chips and the video circuits, with two analog sub boards, EA-6020A and EA-6021A.[3]
- Fan motor board, EA-8020A: a small driver circuit that runs the cooling fan from the +12 V rail.[4]
The main RAM, the memory mapper and interrupt control, and the floppy disk controller sit on boards plugged into four 40-pin connectors on the digital board (CN011 to CN014). Two of them, CN013 and CN014, take RAM boards of up to 128 KB each.[1] RAM can be expanded to 256 KB or 512 KB with the HC-A801MJ kit.[1] The floppy controller is a Fujitsu MB8877A.[1] The power supply has its own board, which the circuit diagrams do not cover.[3][5]
The main RAM is in slot 0-2, which can crash badly written software, and the common POKE workaround for software that mishandles subslots freezes this machine.[1]
Turbo mode and firmware
[edit | edit source]The mode switch on the front selects the Z80 (normal) or the HD64180 (turbo). It also switches the main and sub ROMs, so it must only be moved with the computer turned off.[1] Holding a key during start-up changes the defaults:[1]
- BS: start with the RS-232C software enabled (it is off by default).
- DEL: start with the superimposing function keys disabled.
- ESC: open the System Control menu, which sets the RS-232C and function key options and, in turbo mode, the memory wait states, the I/O wait states and the DRAM refresh interval. The settings are not saved, and turbo settings that a program cannot work with can force a reboot; in the worst case the machine asks for normal mode.
Several programs do not run on the HD64180. One owner found that Nextor stops with kernel error 6 and SofaRun exits at once in turbo mode.[6]
Connections
[edit | edit source]_rear_panel.jpg)
- One MSX cartridge slot at the front.[1]
- RF output on the HC-90, (A) and (B) only; composite video and mono audio output on the (V) and (T) only.[1]
- Stereo audio and composite video input and output, for superimposing.[1]
- RGB output on a 25-pin D connector, wired as RGB21 on pins 1 to 21.[1][6]
- Keyboard connector, RS-232C (DB-25), data recorder, Centronics printer port and two joystick ports.[1]
- Two internal 96-pin expansion connectors.[1]
- Mains input, AC 100 V ±10%, 50/60 Hz, and an AC outlet for a monitor.[1]
The S-video output of the IF-C40SK interface does not work on the HC-90, (A) and (B).[1]
Known faults
[edit | edit source]- Power supply failure. Two HC-95(A) owners on the MSX Resource Center forum found the supply dead; one rebuilt it by replacing its capacitors, and the other was advised to replace every electrolytic in it and measure the output voltages.[7][5]
- Floppy drives not reading. One HC-95 owner found only one of the two drives booting disks, and another found both drives faulty.[8][7]
- Old backup battery. Forum members advised replacing the backup battery before it leaks, and an owner listed the 3 V lithium battery among the parts his HC-90/95 needed.[9][10]
- Software that fails in turbo mode, or because the RAM is in slot 0-2. See above.
The JVC HC-90 Troubleshooting Guide covers these.
Documentation
[edit | edit source]Victor's circuit diagrams for the digital, analog and fan boards, the parts change list, the floppy drive test instructions and the test point waveforms are hosted here as File:Victor HC-90 HC-95 schematics and parts changes.pdf and described on JVC HC-90 Schematics. They do not include the power supply or the floppy controller board.[3] No full service manual for the HC-90 is among those held by the MSX Archive.[11]
Repair guides
[edit | edit source]Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 Victor HC-90, MSX Resource Center wiki, 7 March 2026—link(accessed 2026-10-21) Community page: an MSX2 with two CPUs made by JVC and released in 1986 (infobox date 1986-03-10), nearly identical to the HC-95, which has two disk drives where the HC-90 has one; 100 V; on-board frame grabber and superimposer; Japanese keyboard, light grey; sold with software including Title editor, Telop and Wipe editor; from ¥168,000; versions HC-90, (A), (B), (V) and (T) with a reported (H) version with a 40 MB hard disk; main RAM in slot 0-2, 64 KB or 256 KB with memory mapper; 128 KB VRAM; PSG Yamaha YM2149; Z80A from NEC (µPD780C-1) at 3.58 MHz and Z180 (HD64180) at 6.144 MHz, one at a time by manual switching; MB8877A floppy disk controller; 720 KB 3.5-inch drive; RS-232C; Kanji ROM level 1; firmware System Control menu; connections listed; mains input AC 100 V ±10%, 50/60 Hz.
- ↑ Victor Company of Japan, HC-90/HC-95 board parts changes, printed page 10 (document No. 01129B; PDF page 5 of File:Victor HC-90 HC-95 schematics and parts changes.pdf). EA-1020A digital main board: IC1018 LH0080A changed to UPD780C-1; IC1015 HD74LS393P to HD74HC393P; IC1040 CED40019-00B-IC to CED40019-00E-IC; IC1052 CED40020-00B-IC to CED40020-00E-IC; R1072 resistor network changed; EMI filters K1022 to K1035 added. EA-5020A analog main board: C5573 changed from a 0.1 µF ceramic (QCZ0118-104M) to an electrolytic, part QET50JR-227; peaking coils, zener diodes and transistors changed.
- ↑ 3.0 3.1 3.2 3.3 3.4 Victor Company of Japan, HC-90/HC-95 circuit diagrams, restored by MSXPro. Hosted here as File:Victor HC-90 HC-95 schematics and parts changes.pdf. PDF page 1: analog main board EA-5020A with the analog sub boards EA-6020A and EA-6021A, including IC501 V9938 with four µPD41464C-12 video RAM chips, an MC1377P encoder (Vcc 12.0 V, reference 8.2 V), connector CN502 (1 +5 V, 2 ground, 3 +12 V, 4 −12 V) and the 25-pin RGB connector CN503. PDF pages 2 and 3: digital main board EA-1020A (for the HC-90 and HC-95) and EA-1021A (for the HC-90(A) and HC-95(A)), including IC004 HD64180, IC018 µPD780C-1, IC051 YM-2149 (SSG), IC038 8255, IC019 8251, IC027 8253, IC081 RP5C01 clock with crystal X001 32.768 kHz and battery BT001, reset IC IC002 RST518A with reset switch S001, mode switch S002, cassette input comparator IC057 µPC311C, connectors CN008 (MSX slot), CN010 (JVC extend slot), CN011 (FDD), CN012 (mapper and interrupt control), CN013 and CN014 (RAM boards) and CN015 (from the power supply: 1 +5 V, 2 ground, 3 +12 V, 4 SD, 5 −12 V). PDF page 4: fan motor board EA-8020A.
- ↑ File:Victor HC-90 fan motor board EA-8020A schematic.png, from PDF page 4 of File:Victor HC-90 HC-95 schematics and parts changes.pdf: +12 V and ground in from CN016 on board EA-1021A; R1 3.9 Ω; C2 1000 µF 16 V; zener D1 RD6.8ES(B3); transistors Q1 2SB861(C) and Q2 2SC1685(R,S); output to the fan on CN01.
- ↑ 5.0 5.1 Vhd interface for victor hc90/95, July 2022—link(accessed 2026-10-21) Page 8 of 31. leonlas, 2 July 2022: an HC-95A bought as working, apart from drive B and the missing keyboard, began rebooting after its first start and showed only 16 KB of RAM in a game; the owner suspected the power supply. popolon_, same day: replacing every electrolytic capacitor in the power supply should help if the problem is the supply voltages, and the voltages can be measured with the power on; the schematics linked from the MSX Resource Center wiki do not include the power supply. leonlas, 3 July 2022: the supply gives no voltage; the owner did not know what the yellow "SD" wire is.
- ↑ 6.0 6.1 The Strange case of a Victor HC-95(a) 512KB!, June 2022—link(accessed 2026-10-21) Page 2 of 5. retrocanada76, 6 June 2022: Nextor fails with kernel error 6 when switched to the Z180, and SofaRun exits at once. gdx, same day: the HC-90/95 documentation says the Z80/Z180 switch should be changed only with the computer off, and most games that access the hardware directly do not work in Z180 mode. sdsnatcher73, 4 June 2022: the 25-pin RGB connector has the RGB21 pinout on pins 1 to 21.
- ↑ 7.0 7.1 The Strange case of a Victor HC-95(a) 512KB!, June 2022—link(accessed 2026-10-21) Page 1 of 5. retrocanada76, 3 June 2022: a boxed HC-95(a) whose power supply was not working had to be reconditioned, replacing capacitors; the RAM slots held a mapper board and two 256 KB cards, giving a 512 KB mapper in slot 0-2; the VDP was a V9938; "the floppies seem busted". retrocanada76, 4 June 2022: asked for the floppy pinout, as the drives did not work. gdx, 4 June 2022: the RAM in a 0-x slot is the one thing about the machine he does not like.
- ↑ Victor/Jvc hc-95, February 2013—link(accessed 2026-10-21) Page 3 of 11. RetroTechie, 1 February 2013: the three-pin mains connector on the back is usual on 230 V equipment and unusual on a 100 V Japanese machine; a 230 to 100 V converter is the main issue; powering the machine from a PC supply would need soldering and knowledge of how to bypass the internal supply, which is not easy without a schematic. bateman82, 1 February 2013: the HC-95 worked from a step-down converter; only one of the two floppy drives booted disks.
- ↑ Victor/Jvc hc-95, November 2012—link(accessed 2026-10-21) Page 1 of 11. msxholder, 14 November 2012: the HC-95 is an MSX2 with only the PSG for sound and a second CPU, the Z180 at 6 MHz; replace the backup battery before it leaks, as it is 25 years old.
- ↑ Victor/Jvc hc-95, October 2019—link(accessed 2026-10-21) Page 10 of 11. alexito, 24 October 2019: thanks MSXPro for the schematics; his to-do list for his HC-90/95 includes replacing the 3 V lithium battery.
- ↑ Index of /pub/msx/docs/service_manuals, MSX Archive—link(accessed 2026-10-21) Directory of MSX service manuals; it lists none for JVC or Victor machines.
