FS: Palcom px-7 with 8 Laserdisc games

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By dimmuborgir

Resident (37)

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15-11-2008, 15:44


Buying Cave shooter PCB:s to play. The true Rolls Royce of gaming...

By Bas040

Master (212)

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10-04-2009, 20:42

I have entered last month the world of MSX LD games. Bought a PX-V60, LD700 and 2 LDs

to dimmuborgir: Still LD games for sale? I'm very interested!

to everybody: Somebody wants to get rid of his/her LD games?

I'm anxious to play more LD games!

b_tilborghs @ hotmail dot com

By SLotman

Paragon (1240)

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11-04-2009, 18:31

Someone should dump this LD games... so they can be properly emulated (the ones on Daphne, for what I heard are arcade versions, not the MSX ones!)

By Sd-Snatcher

Hero (582)

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12-04-2009, 10:37

Dump = Digitize. Tongue

By SLotman

Paragon (1240)

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12-04-2009, 18:21

Not only digitize... there are small programs on some of them (at least a basic code to load the game - and the games overlay sprites on video, so there is at least some code to control the sprites), and are the PX7 ROMs dumped too? Or there are no ROM to control the laserdisc at all? (So little information on how it actually works...)

By Randam

Paragon (1430)

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12-04-2009, 20:16

great idea SLotman. I was also wondering why none of the emulators like BlueMSX or OpenMSX emulate these MSXes, or why laserdisk images aren't supported. Too little documentation on how those work or is there another reason?

By seanyoung

Resident (58)

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12-04-2009, 22:43

Noone has so far worked out these systems work, at least well enough to emulate. I'm working on this right now, actually. I can play Badlands in my openMSX build with sound but no video so it's very hard. Smile

The Palcom MSX contains an 8KiB ROM, some control logic for the LD interface and a superimposing unit. As far as I can work out, the data traveling to the Laserdisc is much like the infrared remote control protocol. There is a "command complete/seek done" feedback though. The Daphne documentation does not describe the LD-700 protocol, so I had to reverse engineer it.

The beginning of right audio channel contains the code for the game -- when you load a laserdisc game with "call ld" the right channel is muted, you'll notice. An simple audio dump will suffice for that -- my current implementation uses vorbis and the data block survives the vorbis encoding and decoding fine. There is some ugly hardware kludge to make the right audio channel connected to the tape in. However, this has a custom format so regular bload or so won't work.

Note that simply capturing the video and audio of a laserdisc is not enough to emulate it. The laserdisc contains information on frame numbers and chapter numbers, also the laserdisc can pause at certain frames (Cosmos Circuit does this at the beginning of chapter 2,3,4,5). This information (pause/frame/chapter) is encoded in the VBI as well, so when capturing laserdiscs the VBI must be captured too and processed into some format the future emulators can understand.

By SLotman

Paragon (1240)

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13-04-2009, 02:21

Wow, first "real" info about how it works... nice!!

apart from all those problems reported by seanyoung, emulators will also have to be adapted, to draw the screen normaly, then to render the video on top of it, and then render sprites on top of it all! Or does the LD games uses the super-imposing features of the VDP, and so this won't be a problem for emulators...?

Good luck to you Sean, I would love to see LD games on emulated some day Smile

By Manuel

Ascended (18699)

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13-04-2009, 13:49

SLotman: the PX-7 does superimpose, all MSX stuff is on top of the video image.

By Gradius2

Hero (639)

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20-08-2009, 08:33


It doesn't just superimpose the video, but the audio as well.

Can you please post the program audio capture (48KHz @ 16-bit in flac with WinRAR) on Internet seanyoung ?

So a lot more would be able to do reverse engineer. Badlands isn't hard at all to emule on DVD player, I'm 99% sure I can do that, but I need to look the code, it uses almost no sprites, only the score part would be hard to put as DVD-Video standard.

Perhaps the best solution would be to adapt openMSX just to run those LDs games, like openMSXLD or something. The video can be mpeg2, but I prefer h.264 these days.


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