Description

Computer

The Victor HC-90 is a personal computer with two CPUs made by JVC (Japan Victor Company) and released in 1986. It is nearly identical to the HC-95, the only difference being that the HC-90 has one disk drive and the HC-95 has two.

It was released in 6 versions (see below) and 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.

Notes:

• The RAM can be expanded to 256kB or 512kB with the HC-A801MJ expansion kit.
• S-Video output of the IF-C40SK interface does not work in models HC-90, HC-90(A) and HC-90(B).
• The Philips NMS 8260 is a prototype made by Sanyo and JVC of an MSX with built-in 20MB hard disk drive. The HDD rom of that machine includes a reference to the JVC HC-90/HC-95.

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

The launch price for each "normal" model was 168,00 yen.

Switches

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.

Versions

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):

• Differences on HC-90(A) compared to HC-90 are FDC board and main board that have received minor changes.
• Differences on HC-90(B) compared to HC-90(A) are FDC board, analog circuit and power supply that have been updated. A search switch has been added. Drive front panel cannot be seen from the outside.
• Differences on HC-90(V) compared to HC-90(B) are 256kB RAM with Memory Mapper that replace the plain 64kB RAM, update of the VDP to the MSX2+ VDP (without changing the BIOS roms), new keyboard connector (D-SUB). Sound and video outputs replace the RF converter. A through switch replaces the color enhancement switch on front. The HC-90(V) appears to have only been sold in the professional market with dedicated teloper software.
• HC-90(T) is almost the same as HC-90(V). 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.

Besides these 5 'normal' versions, according to the words of a person who worked at Victor company and a few other people, a 6th version was produced to meet the demand of cable TV, the HC-90(H) with built-in 40MB hard disk drive. At that time the Japanese cable TV channels (CATV) were local so they had a small budget. The HC-90/HC-95 was often used because relatively cheap. Victor would have simply produced the HC-90(H) for this reason.

Launching

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 wait states
• (only in Turbo mode) I/O wait : 3 wait states
• (only in Turbo mode) DRAM refresh cycle, insertion interval: 80 states

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).

Function keys

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

Firmware

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

(*) the menu proposes here the values 0, 2, 3 and 4 - it does not propose the value 1

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.

Pictures

Computer

Victor HC-90(A) front detail

Victor HC-90(T)

Victor HC-90(T) label

Victor HC-90/95 back - 1st version and version A

Victor HC-90/95 back - version B

Victor HC-90 with disk and manuals

Victor HC-90/95 back - versions V and T

Victor HC-90/95 back -versions V and T - with IF-C40SK interface

Victor HC-90/95 keyboard

Victor HC-90(A) Main board

Firmware

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

Specifications

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.

The 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

• (*) 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.

Connections

• 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
• Keyboard connector
• RS-232C connector (DB-25)
• Data Recorder connector
• Centronics compatible Parallel port for a printer
• 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)

Links

• HC-90/95 Schematics
• Slot map from the manual
• HC-90/HC-95 versions comparison and more about the variations by Hiro Yuki (Japanese)