Victor HC-90/95 Laserdisc operation experiments

By dproldan

Resident (44)

dproldan's picture

20-03-2023, 18:50

I recently got two nice MSX related machines: A Victor HC-90 computer (without keyboard) and a Sony Lasermax LDP-3600D laserdisc player.
I've always been fascinated by the laserdisc technology and got these two devices just to try and make them work together if possible.
As I have no keyboard for the Victor, I'm using a PS2 adapter I made some time ago

To connect these two together, I used a cable as described in the Sony_LDM-G1000_Protocol_and_Command_Manual_for_Sony_LDP_Series_Videodisc_Players.pdf (You need the crossed cable) There's plenty of information related to the Sony MSX and LD connecttion in that document.

You need to boot the MSX with the "backspace" key pressed, in order to have the RS-232 port enabled.
After turning on both units, the "ext CPU" led in the LD player will stay on if the cable is correct and is connected.

I made a small program to turn on the SuperImpose function and set up a comms channel to send some commands:

Available here :

When running that program, the picture is inmediately shown on the display and you can start sending keystrokes, followed by "enter" key:
"B" to start playing from the beginning.
"*" to eject the disc
">" to fast forward
etc... There's a incomplete list here:

Some more tests I'd like to do:
1.- Load the ROM extension present in the Sony HB-G900 video utility, that provides the _LDPINIT related basic commands. I made a cartidge with that ROM file and I can indeed send a _LDPINIT command now, but it hangs the computer. I don't know the reason.

2.- Load the disc data as if it was a tape. I have extracted the audio form the correct channel and it certainly sound like a tape data, but I can't make it work in OpenMSX. I guess it's not the same format.
Audio capture available here:

Any help is appreciated. Ideas are welcome!

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