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Compaq portable 286 with EGA wonder

ghosthuntergr

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May 7, 2019
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Hi, I have a compaq portable 286 and soon I will have an EGA wonder card. I want to replace the cga of the unit with the ega wonder and connect to the internal mono display.
The problem is I don't have the compaq adapter on the EGA wonder and I haven't been able to find any information or a picture of it.
So I want to try and make one, probably through the feature connector of the card. Does anyone know about the pinouts for feature connector and for the internal monitor of the compaq?
 

Trixter

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I'm pretty sure the ATI EGA Wonder had two composite pins on it, which is what connects to the monitor internally. The feature connector is not involved.
 

Eudimorphodon

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My vague recollection is that the internal monitor on an IBM 5155 portable is composite, but is the Compaq Portable's monitor also composite? I thought it was some special dual-mode thing that supported both 200 and 350 scanlines. (Which I suppose would be technically possible with composite, but I also vaguely recall the internal connector on the Compaq video card had more than two pins.)
 

Thallanor

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My vague recollection is that the internal monitor on an IBM 5155 portable is composite, but is the Compaq Portable's monitor also composite? I thought it was some special dual-mode thing that supported both 200 and 350 scanlines. (Which I suppose would be technically possible with composite, but I also vaguely recall the internal connector on the Compaq video card had more than two pins.)
Correct. :) It's hard to tell from this picture, but it's 10 pins. (Not sure if all are in use, as I've not counted the wires on the bundle, but it's more than two.) :)
1050329.jpg
 

ghosthuntergr

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Yes it is 10 pins. It is actually a dual display offering MDA text mode and CGA graphics mode. I am trying to find what is the optional compaq connector for EGA wonder to drive the internal display but I haven't found anything. I assume that it will be something from the feature connector providing RGB signals to the internal connector.
 

ghosthuntergr

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Pinout

Pinout

Also here I have found this for the internal connector of Compaq monitor.
----------------
| 1 2 3 4 || 5 |
| 6 7 8 9 || 10|
----------------
1 - Red - VSync - Negative Pulse ~150us All Modes, 50Hz MDA, 60Hz CGA
2 - Black - CGA Mode Active? - High in CGA mode, low in MDA mode. My CRT appears to multisync
and ignore this.
3 - Orange - Analog video data - ~3V max observed
4 - Brown - Hsync - Positive Pulse ~5us All Modes, 15.7kHz CGA, 18.5kHz MDA
5 - Grounding Strap
6,7,8,9 - White - Video Ground
10 - NC
 

soviet9922

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Yes on the ibm portable the connection is directly to the ega wonder board.

But on the case on the compaq this is not possible some kind of circuit interface will be needed to get the thing working on the internal display.

This guy seems have the nak for it and done this by itself in this thread he explains:
http://www.vcfed.org/forum/showthread.php?50640-EGA-on-built-in-CRT-of-Compaq-Portable-1

The issue is that he never provided a schematic on the thread i PM him several times but seems he have been inactive on the forum for years.
 

ghosthuntergr

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Yes I have seen this post but without a schematic you can only guess... At least I want a photo of the compaq board of ega wonder to see how it is and where it is connecting
 

Eudimorphodon

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The circuit in the other thread looks like a pretty simple resistor ladder DAC to my ignorant eyes. I assume he's using the op-amp for the final output stage because the voltage levels required by the Compaq monitor is too high for resistors driven by TTL outputs to supply? (VGA analog only swings from 0 to .7v, so there are resistor-ladder circuits out there for VGA that don't have amplifiers.) Does anyone have the pinout for the EGA Wonder's connector?
 

soviet9922

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Searched high and low for the pinout and theres none only, but found this is from the ibm ega videocard i suppose the ega wonder one must be a clone of this one.
 

ghosthuntergr

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I think that the feature connector on EGA wonder has support for TTL monitors because as I have seen in the manual of EGA wonder the switches for internal Compaq monitor is around the same as for MDA monitors.
 

ghosthuntergr

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Hi, thanks but there is a major difference. The internal ibm monitor is a composite one and compaq’s is a dual sync mda &cga display. In the internal connector of the compaq monitor, there is only one video pin which somehow understands what video mode the internal video card of the portable is in and adjusts the frequency. It is referenced as analog data but when i send mda ttl video it works. When I send also one of digital rgb color of cga or ega e.g. blue it works.
E3048643-99BD-42A4-B3FB-32D9086B0B1E.jpg
 

ghosthuntergr

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I have managed to get cga and ega modes directly to the internal monitor. Here s the schematic. You will need 3 diodes for protection.

6F308C9C-FE72-46C5-83DD-6461277AF374.jpg
 

retro-pc_user

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Does that get soldered directly onto the pins on the EGA Wonder card or not really?

Sorry for bringing a close to 2 year old thread back to life here.
 

illys

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I am running in a similar challenge and I spent some time here.

Just to help future would-be-me: I do not know how good this schematics work, but it only covers CGA output of the EGA card (low resolution up to 640x200).
Indeed the ATI EGA Wonder has the switches set for a CGA monitor, so we are wasting the 640x350 capabilities of both the EGA standard and Compaq monitor.

My challenge is to connect an ATI EGA Wonder to a stand alone dual-mode monitor of a VDU Compaq Deskpro, and I suspect the VDU DB9 connector to behave very closely to the internal connector of the same VDU card (at least in high res. mode: low res. mode is actual CGA with the stand-alone monitor).

My idea to support 640x350 modes with proper Compaq frequencies (CGA 15.7 kHz + MDA 18.43 kHz): we need to set up the ATI card switches either to the specific "Compaq Internal Monitor" settings or to the "TTL Monochrome" (MDA Monitor), and then create an adapter to feed the Analog Video Data line of the Compaq monitor from either the 6 EGA color lines (best result?) or from the 2 MDA video+intensity lines (easiest circuitry?).

Need to get an oscilloscope to continue :-/
 

benoitmabille

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Apr 5, 2019
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Time flies... i have an EGA Wonder and am also puzzled what the Adapter does to connect to the portable internal display. Or what alternative hack we could do...
 
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