Description

VHD means Video High Density and AHD means Audio/Advanced High Density. This system, released only in Japan by JVC/Victor, is different from the LaserDisc system released by Pioneer.

Instead of being on optical disc, similar to a very large CD-ROM it is more similar to a LP record. Just like a LP it had two sides, requiring you to swap the disc over. But unlike LP it had a caddy to protect the disc.

Various movies were released in Japan on VHD format, and VHD was also marketed for use with MSX and Sharp X1. Many compatible VHD players and interfaces have the VHDpc logo. Several games were made for this system.

Youtube video about the history and operation of VHD

VHD hardware

VHD Interfaces for MSX

Several VHD interfaces for MSX support VHDpc features.

A VHDpc interface is able to read an interpreted program similar to BASIC digitally recorded onto the VHD (on the track B audio channel) that can be executed by any computers that uses an interface and associated player with the VHDpc logo. Thus no need for an external program (usually on tape) to run an interactive software on VHDpc.

(*) Notes:

• Most Japanese Toshiba computers can be used with the MSX1 interfaces when they are extended with the Toshiba HX-T330 superimpose unit
• Similar computers such as Yamaha CX5, CX5F, YIS-503, etc. can also be used with the MSX1 interfaces if you add the HC-A602S module
• The very low RAM of Victor HC-5 will prevent to run most VHD games, if you don't add at least 16kB RAM

VHD Interface description

Used I/O ports are the following.

The connector on backside of the player is a standard DIN 13-pin.

The following table is the interface board decription for the Sharp X1 VHCpc controller interface VO-20PS. The MSX interface might have a similar design to control the same VHDpc compatible players. Taken from http://x1center.org/sdx1/sdx1_0.html

VHD / VHDpc players compatible with MSX

Notes:

• It was possible to change the needle of the VHD player by using a National VDS-1100S or Victor VDS-1100 stylus replacement cartridge
• Although having the VHDpc logo, the Sharp VP-2400 and Sharp VP-X10B players are not compatible with MSX. They don't have a DIN 13 connector, but a DIN 8 connector and are aimed to be used with a Sharp X1 computer.

VHD software for MSX

Only ten software titles are known to have been commercialised for MSX. Just like the VHD hardware they are very rare and only ever released in Japan.

There are two kinds of VHD games:

• Games such as Alice in Chemical Reaction, The Players Club and VROOM are written in an interpreted (intermediate) language and are recorded on the VHD itself. This requires the computer to have an interpreter for the VHD language and has implications as to the type of games that could be developed due to the overhead of an interpreted language.

• Games such as Road Blaster, Thunder Storm and Time Gal were specific to the MSX (or Sharp X1) computers, but instead of writing the game onto the VHD, the game was provided on a system specific tape while the VHD contains only the pictures and the soundtrack(s).

Most of the VHD software for MSX has a stereo sound. The only known VHD software for MSX with mono sound is VROOM.

(*) VHD + tape
(**) 2 VHD's - MSX2 required (was tested on a dual VHD system controlled by a HC-95 computer, but probably not commercialised)

Example

Thunder Storm VHD

Thunder Storm tape for MSX

Links

• How to play Thunder Storm on PC (Japanese)