Which laserdisc-players can be used with the MSX?

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By mohai

Paladin (932)

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27-08-2018, 18:50

Hello again.
After some resesearch and investigation, I found out that almost every Laserdisc from Pioneer can be connected to a PX-7 (or compatibles such as PX V60).
I purchased a CLD-1450 Laserdisc player but was unable to control it with a simple mono-jack cable from "output 2" from PX-7.
It seems that remote commander protocol is the same in both MSX and LD player but, as PX-7 has 3 outputs in it, 3 different wave formats are output.
"Output 2 " is not suitable for this LD model, but I think "output 3" does.
Currently, I am doing a special cable for it (from he damned U-shaped din 8 to mono jack) to check it.
Will keep you posted.

By Alexandre_Taito

Champion (325)

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28-08-2018, 20:54

I said it years ago... Smile

By Stt1

Hero (578)

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29-08-2018, 13:16

I tested these beasts quite a bit already about 20 years ago. It was really experimental back then as I couldn't ask help from anyone in the forum Smile

Conclusions back then:

PAL PX-7 + NTSC LD-700 -> kind of works, but a lot of trouble (unusable), just as you found out.
PAL PX-7 + composite NTSC -> PAL converter + NTSC LD-700 -> works better, but picture quality is degraded and still timing issues and glitches.

I didn't try to convert PX-7 from PAL to NTSC model as I didn't have any technical manual for digging info and these computers were dirt cheap (compared what they cost now) back then, it was just easier to get NTSC model to complete working setup. BTW, it seems that the prices are again slowly coming down, especially for units without keyboard.

About the communication cable. I have strong belief that the mono-cable was never actually used in gaming. I base this belief that I haven't seen any LD-1100 with the mono plug for connecting MSX. Also, there is a clear problem with this two pin cable as the third communication line is missing (input to MSX). This line comes from LD player itself and seems to contain only ACK-signal. If this is missing the "loading" continues infinitely as computer does not get the signal when certain frame has been played and program should be executed again.

Basically you should be able to command LD player (basic commands without needing the ACK) via mono-cable and IR transmitter. And as far as I have understood, even fairly new Pioneer LD players do use the same command protocol (there are few exceptions in the very late/hifi-models).

By mohai

Paladin (932)

mohai's picture

05-09-2018, 20:32

Thanks for the info.
This is what I did:

Cable from OUTPUT 3 (DIN 8) to mono jack to LD-1450 player - only using pin 7 and gnd.
A/V out from LD player to PX-7 (audio not inverted).

PX-7 is able to control the LD player from BASIC commands but only as non-LD-700, as ACK signal is not connected.
It is able to even load a game and show the menu but ...

When "genlocking" from an NTSC (or PAL60) source, VDP seems to adapt to video input frequency and shows correct screen and colours BUT, BIOS seems to freeze in a loop due to interruptions are too much to handle. Keyboard does not respond.
When external video is disconnected, MSX unfreezes and BASIC keeps on running. Nothing broken by now ! Big smile

That is the reason why PX-7 is freezing after loading a game.
After a CALL LD, the game is loaded correctly. That means that BIOS and Z80 are still running, but INTs maybe are wrong, so BIOS cannot read keyboard and I cannot start game and maybe some other odd stuff due to INTs.

I think that one solution could be to change VDP to a NTSC model (TMS9928a), but maybe some other internals need to be changed too (maybe some day I will try).
I am waiting for an NTSC-to-PAL (bi-directional) converter to keep testing.

** LD-1450 is a special model that plays both PAL and NTSC discs, converting NTSC to PAL60 ...

By mohai

Paladin (932)

mohai's picture

05-09-2018, 20:40

Stt1 wrote:

About the communication cable. I have strong belief that the mono-cable was never actually used in gaming. I base this belief that I haven't seen any LD-1100 with the mono plug for connecting MSX. Also, there is a clear problem with this two pin cable as the third communication line is missing (input to MSX). This line comes from LD player itself and seems to contain only ACK-signal. If this is missing the "loading" continues infinitely as computer does not get the signal when certain frame has been played and program should be executed again.

I do not think that ACK signal is a problem, as the PX-7 has a register to detect whether external video input is active or not so, when a "frame display" command is issued, it will always knows when the frame is ready.
This way, other players (such as the LD-1100 or modern players) can be controlled with no issues.

Stt1 wrote:

Basically you should be able to command LD player (basic commands without needing the ACK) via mono-cable and IR transmitter. And as far as I have understood, even fairly new Pioneer LD players do use the same command protocol (there are few exceptions in the very late/hifi-models).

I agree.
In some LD players you can read: "if it the "SR" log is show, then it can be connected to a device with the same logo and controlled from it".
Now, look at the front of the PX-7 (and compatibles). That "SR" logo is there ... Wink

By mohai

Paladin (932)

mohai's picture

02-10-2018, 20:51

Some updates:

mohai wrote:

Cable from OUTPUT 3 (DIN 8) to mono jack to LD-1450 player - only using pin 7 and gnd.
A/V out from LD player to PX-7 (audio not inverted).

PX-7 is able to control the LD player from BASIC commands but only as non-LD-700, as ACK signal is not connected.
It is able to even load a game and show the menu but ...

Correction: I can control Laserdisc player from BASIC using LD-700 commands (such as CALL REMOTE(0,"P+") but, as LD-700 mode seems to check /LACK pin, command is sent an then an error message is shown: "Device I/O error".

Workaround: Define a device with command CALL DEF UNIV(3,&HA8) and then use commands with device 3. No more errors are shown. (In fact, device ID A8 is the standard ID for Pioneer Laserdiscs, the same as LD-700, but /LACK pin is not checked if the device is different than LD-700).

As the 3 outputs in the PX-7 work together but, with different electrical values, any command sent to Laserdic, will be outputted in the 3 connectors at the same time.

mohai wrote:

When "genlocking" from an NTSC (or PAL60) source, VDP seems to adapt to video input frequency and shows correct screen and colours BUT, BIOS seems to freeze in a loop due to interruptions are too much to handle. Keyboard does not respond.
When external video is disconnected, MSX unfreezes and BASIC keeps on running. Nothing broken by now ! Big smile

That is the reason why PX-7 is freezing after loading a game.
After a CALL LD, the game is loaded correctly. That means that BIOS and Z80 are still running, but INTs maybe are wrong, so BIOS cannot read keyboard and I cannot start game and maybe some other odd stuff due to INTs.

I am waiting for an NTSC-to-PAL (bi-directional) converter to keep testing.

Well, NTSC-to-PAL converter finally arrived and seems to work fine.
I tested it with the Laserdic player in pure NTSC mode and the PX-7 (PAL) seems to load the games does not freeze anymore. Cool

Now, the issue is that, after loading the game, the disc seems to not stop. It keeps playing and player does not seem to respond commands sent from PX-7. Sad
If I start to play the game, the disc just keeps playing, so the images are not in sync with the game.

I know this player accepts commans to skip to a specific chapter, skip to a specific frame or time, as I tried these commands from BASIC and all of them seem to work. Maybe is the game itself that is sending old comands unknown to this model.
This is something I have to investigate ...

By mohai

Paladin (932)

mohai's picture

27-11-2018, 11:47

Hello,
Just a little update:

modern players seem to accept all the commands used in a game, such as "show frame nnnn" or "show time nnnn" or pause ...
I think the problem is that some commands could be hardcoded in the game or the Pioneer ROM itself. This is something I have to find out yet.
As I said before, working from BASIC, selecting a non- LD-700 player, such commands seem to work fine: "show frame nnnn", "show time nnnn", but, they do not work at all from the game.
Working in BASIC, if I send the command to show a specific frame, I can see the OSP form the LD player asking for the frame number and, if sent correctly, it accepts it and shows it.
This behavior is not shown when the game is running and (I guess) it should show an specific frame.
I will need to monitor what are the command codes that game sends to player and them compare to the ones send in BASIC.
If the command codes are managed by the BIOS, then maybe a patched BIOS can be done, in order to conform modern player but, if the command codes are managed directly by the game, then the game cannot be played with "any" player, but only a few specific players.
On the other hand, maybe a player can be hacked to accept different codes to conform the game codes (I am just guessing). Some kind of BIOS inside the player could be modified?

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