Victor HC-90
This page was last modified 22:40, 4 April 2018 by Mars2000you. Based on work by Gdx and Msxholder and others.




The Victor HC-90 is a personal computer with two CPUs made by JVC (Japan Victor Company) and released in 1986.

This model uses a c13 power connector this is unusual for a non european device. it is 100 Volt.

This computer features on-board frame grabber and superimposing capabilities. It is especially useful if you use it in combination with the IF-C9C VHD interface and a VHD (Video High Density) player.

A front switch allows to run this machine in normal mode or in Turbo mode. It has indeed two CPUs, the usual Z80 and the unusual Z180. This switch must only be changed when the MSX is turned OFF because it also switches the Main-ROM and the Sub-ROM.

Besides this switch, the HC-90 has in front sliders to control the color enhancement, the audio mix and the color tint. On some versions, a switch at the back allows to enable or disable the automatic search of synchronisation for superimposing. On the two last versions, the color enhancement switch is replaced by a through switch, allowing to make transparent useless part of a picture.

If you launch this computer without pressing BS, DEL or ESC during the boot sequence, it will start with the following default parameters:

  • RS-232C disabled
  • Function keys for superimposing enabled
  • (only in Turbo mode) Memory wait: 0 millisecond
  • (only in Turbo mode) I/O wait : 3 milliseconds
  • (only in Turbo mode) DRAM refresh cycle: 80 milliseconds

To start with the RS-232C software enabled, you need to press BS when booting.

To start with the function keys for superimposing disabled, you need to press DEL when booting.

If you press ESC when booting the computer, you will access to the System Control menu (see firmware).

When the function key option is not disabled at startup, superimposing can be controlled directly with the function keys (without using MSX-BASIC instructions):

  • CTRL+F1 = display superimpose, audio is mixed
  • CTRL+F2 = display television, audio is mixed
  • CTRL+F3 = display computer, audio is NOT mixed
  • CTRL+F4 = display superimpose, color 0 is not transparant, audio is mixed
  • CTRL+F5 = display superimpose, half brightness, audio is mixed
  • CTRL+SHIFT+F1 = select RGB video input
  • CTRL+SHIFT+F2 = select BNC video input

Five versions of the HC-90 for the 'normal' users are known to exist (you need to check the label to know the exact version):

Version RAM VDP RF
CVBS + mono
audio output
HC-90 64kB V9938 Yes No Yes No No 20-pin
HC-90(A) 64kB V9938 Yes No Yes No No 20-pin
HC-90(B) 64kB V9938 Yes No Yes No Yes 20-pin
HC-90(V) 256kB V9938 No Yes No Yes Yes D-SUB
HC-90(T) 256kB V9958 No Yes No Yes Yes D-SUB

  • Differences between HC-90 and HC-90(A) are FDC board and main board that have received minor changes.
  • Differences between HC-90(A) and HC-90(B) are FDC board, analog circuit and power supply that have been updated. A search switch has been added. The front panel and floppy disk drive are different.
  • Differences between HC-90(B) and HC-90(V): 256kB RAM with Memory Mapper replace the plain 64kB RAM. Sound and video outputs replace the RF converter. A through switch replaces the color enhancement switch on front. New keyboard connector (D-SUB).
  • Main change in HC-90(T) is the update of the VDP to the MSX2+ VDP (without changing the BIOS roms). Floppy disk drive is new and a few other changes have been made (shield cover, etc). This model was made only on special request of the customers.

Note: S-Video output of the IF-C40SK interface does not work in models HC-90, HC-90(A) and HC-90(B).

Besides these 5 'normal' versions, there's a 6th version for cable TV, the HC-90(H) with built-in 40MB hard disk drive.

The HC-90 was aimed at the Japanese market and features a Japanese keyboard. It is available in light gray. It was sold with several software: Title editor, Telop (television opaque projector), Wipe editor, etc

Official price of the 'normal' versions: ¥168,000.

Brand Victor
Type HC-90
Year 1988
RAM 256kB (versions V and T) or 64kB (other versions) in slot 0-2
VRAM 128kB
Media MSX cartridges, 720kB 3,5" floppy disks
Video Yamaha V9958 (MSX2+ VDP!) (version T) or V9938 (other versions)
Audio PSG (Yamaha YM2149)
Chipset none (separate IC's)
Extras Z180 (HD64180) at 6.144 MHz as alternative CPU, CPU switch, 720kB 3,5" floppy disk drive, reset button, RS-232C interface, RS-232C BASIC, superimposition and frame grabber capacity, sliders for audio mix and color tint, Kanji-ROM level 1, firmware (system control), (only first version, A and B versions) color enhancement switch, (only B, V and T versions) search switch, (only V and T versions) through switch


The built-in firmware gives you control on the working of the computer. The System Control menu can be accessed by pressing the ESC key while booting the HC-90.

According the machine is in normal mode or in Turbo mode, you will be able to change 2 or 5 parameters:

  • enable/disable the RS-232C software
  • enable/disable the function keys for superimposing
  • (only in Turbo mode) specify the memory wait (0, 1, 2 or 3 milliseconds)
  • (only in Turbo mode) specify the I/O wait (0, 1, 2, 3 or 4 milliseconds)
  • (only in Turbo mode) specify the DRAM refresh cycle (10, 20, 40 or 80 milliseconds)

Browsing in this menu is made with the up and down cursors, selecting with the left and right cursors. Pressing the HOME key restores the default value for the parameter corresponding to the arrow.

When you are satisfied with the selected parameters, press RETURN to launch the computer with these parameters. In case you have modified one or several Turbo parameters, the computer will first make a soft reset.

Note that

  • all these parameters are not saved by the system, it means that after switching off the machine or making a hard reset, the default parameters will be used for the next use of the computer if you don't change them at startup.
  • in Turbo mode, it can happen that a software can't work properly with the selected parameters. You need then to reboot the machine and try with other parameters. In the worst cases, the soft reset will lead to a screen inviting you to use the normal mode.



Victor HC-90(A) front detail
Victor HC-90(T)
Victor HC-90/95 back - 1st version and version A
Victor HC-90/95 back - version B
Victor HC-90/95 back - versions V and T
Victor HC-90(T) label
Victor HC-90/95 keyboard
Victor HC-90 with disk and manuals


Victor HC-90/95 settings in Z80 mode
Victor HC-90/95 settings in Turbo mode
Victor HC-90/95 warning screen in Turbo mode


The HC-90 is an MSX2 with two CPUs, a Z80A processor from NEC (PD780C-1) at 3.58 MHz and a Z180 (HD64180) at 6.144 MHz. A single CPU may be used at a time by manual switching.

Floppy Disk Controller chip is the MB8877A. The adresses 7FF8h~7FFFh of the FDC and RS-232C Roms are used to control the I/O ports of floppy disk drives, RS-232C and system.

Details about the I/O Map can be found here: Victor HC-90/95 I/O Map.

The main RAM is present on slot 0-2, a configuration that can cause poorly written software to crash. Also, with this layout, the POKE-1,(15-PEEK(-1)\16)*17 trick to workaround buggy software that does not handle subslots properly will cause this machine to freeze.

Slot Map

Slot 0-0 Slot 0-1 Slot 0-2 Slot 0-3 Slot 1 Slot 2 Slot 3
Bank C000h~FFFFh 64kB RAM
Bank 8000h~BFFFh
Bank 4000h~7FFFh Main-ROM* RS-232C &
System control
Disk ROM
Bank 0000h~3FFFh Sub-ROM*
  • (*) Rom replaced in turbo mode with turbo mode support Rom (only 0000h-3FFFh part for the Main-ROM)
  • Addresses 7FF8h~7FFFh in slots 0-1 and 3 allows to access floppy disk and system control registers.


  • RGB output (D-Sub25 connector)
  • RF output on HC-90, HC-90(A) and HC-90(B) only
  • Composite video and mono audio output on HC-90(V) and HC-90(T) only
  • Analog stereo sound & Composite video output
  • Analog stereo sound & Composite video input
  • Data Recorder connector
  • Keyboard connector
  • Centronics compatible Parallel port for a printer
  • RS-232C
  • 2 general connectors (Joysticks, Mouse, Paddle controlers, etc)
  • One MSX cartridge slot at the front
  • 2 custom connectors of 96 pins for expansion card (inside)
  • 4 custom connectors of 40 pins (inside)
    • Connectors ⓵ (CN013/CN014) for Ram board (there are two connectors that can each hold until 128kB)
    • Connector ⓶ (CN012) for Memory Mapper I/O & INT board
    • Connector ⓷ (CN011) for FDC board
  • Power plug male for main power supply (JIS C 8303 class, AC 100V +/-10% 50/60Hz)
  • AC power plug socket (for the monitor)