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This is the pinout for the internal screen connector of a 1986 Toshiba T3100SX 'laptop'. The screen itself is a orange neon gas plasma display (although they also made some with an LCD).

enter image description here

Does anyone know what the protocol is?

This pinout comes from the maintenance manual, which is very patchy regarding technical information --- so the above is all I've got. I know that DSPV is probably +12V. PDP and COLOR will be used to tell the video hardware whether the laptop has the gas plasma or LCD screen plugged in, and I bet that BRCNTM is something to do with brightness. The numbers after the pins are significant, but I don't know what they mean yet.

The screen will display VGA with 16-colour greyscale, so it's probably really simply clocking the pixels in at the right rate. The four-bit wide buses corroborate that. I'm not sure why there are two, though; left and right? Also I'd expect to see lines for horizontal and vertical sync, so unless these are what LP and FP are, then I'm wrong.

The motherboard itself seems to use a bunch of custom ASICs to generate the signal, so there's no help there.

I'm sure someone should be able to tell at a glance what this is. Any ideas?

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    \$\begingroup\$ LP should be line pulse, FP frame pulse. Same as for STN LCDs. When there are two sets of data lines, they usually are for even/odd pixels. \$\endgroup\$ – Janka Oct 31 '17 at 23:48
  • \$\begingroup\$ I'm wondering if the numbers after the semicolons in the signal names are some kind of cross-reference to other parts of the schematic... page numbers, perhaps? \$\endgroup\$ – Dave Tweed Nov 1 '17 at 3:59
  • \$\begingroup\$ Is the device nonfunctional and fubar? If not, maybe you can observe something on the lines \$\endgroup\$ – PlasmaHH Nov 1 '17 at 8:57
  • \$\begingroup\$ @Janka: aha --- having gone and looked them up, it could well be an STN interface. It's the right era for it, and it makes sense given the screen can be swapped out for a monochrome LCD. It may be worth connecting up to a VGA socket; with positive sync pulses the voltages should (may...) be compatible, and the timing should be right. I ought to see something. Certainly worth a try; thanks! \$\endgroup\$ – David Given Nov 1 '17 at 14:24
  • \$\begingroup\$ @PlasmaHH: sadly, it's not functional. Hence why I have a spare display! \$\endgroup\$ – David Given Nov 1 '17 at 16:23

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