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ibmapc
April 29th, 2010, 05:50 PM
I'm thinking about getting a "Diamond Speedstar VGA with ET4000 chipset " as listed in the wiki as an 8 bit friendly vga card . Will I be able to use this card in my IBM 5155 Portable together with the original CGA card? I want to be able to continue to use the internal monitor, although I don't need to have the internal monitor active at the same time as the VGA. When I looked into putting an IBM EGA card in it way back in 1986, the CGA would have to come out first and since the internal monitor is conected to the CGA card I decided to pass on the EGA card. If the CGA and VGA cards can not reside at the same time, does anyone have a suggestion for upgrading the video without loosing use of the internal monitor?

Greg

vwestlife
April 29th, 2010, 07:45 PM
If you want to use a VGA card together with existing CGA video, then the VGA card will only be able to display monochrome text, and possibly Hercules emulation monochrome graphics. You can't use CGA and color VGA in the same computer, because they would try to both use the same addressing and video memory mapping, and the system would get terribly confused.

ibmapc
April 29th, 2010, 08:35 PM
That's what I was afraid of. Anyone know where I can find an ATI EGA WONDER. I could replace the CGA with it and connect the internal monitor to it.

Anonymous Coward
May 1st, 2010, 12:08 PM
I am pretty sure that CGA and VGA cards cannot be installed simultaneously, because their bioses both require use of the same location in memory.

In theory it would be possible to connect a VGA card to the composite display in the 5155, but you would have to build a VGA to composite converter circuit and do a little soldering.

Chuck(G)
May 1st, 2010, 01:35 PM
There do exist VGA cards with connectors for CGA as well as VGA. I think I've got a Video 7 version somewhere...

ibmapc
May 1st, 2010, 04:09 PM
There do exist VGA cards with connectors for CGA as well as VGA. I think I've got a Video 7 version somewhere...
Would you be able to tell me how to connect the 5155's display to the CGA on a Video 7? Mind you I'm not very skilled with a solder iron. Would probably have to have someone do the soldring for me. (if required)

Thanks,

Greg

Chuck(G)
May 1st, 2010, 05:14 PM
I'm going to beg off of that one. My feeling is that for someone experienced in such stuff that this would be pretty simple. Maybe another forum member wants to guide you through this one.

southbird
May 1st, 2010, 06:00 PM
There also exists just off-the-shelf VGA -> TV (Composite) conversion devices. I have one, runs off 5V, can easily integrate with a 5155. (I actually had one set up with it briefly until I broke the yoke of the internal monitor D: ) That's really the easiest and most guaranteed route, I think. In my experience the internal monitor works fine though there are some clarity problems in 640x480 VGA... (After all, there's only 200 lines on the display, right? It is 640 wide, though!) But if you're keeping the system pure, you're not likely to be doing a lot in 640x480 VGA anyway. Also it's not unreadable, just a tad fuzzy vertically.

Mike Chambers
May 1st, 2010, 06:43 PM
There do exist VGA cards with connectors for CGA as well as VGA. I think I've got a Video 7 version somewhere...

i've got a cirrus logic that has both connectors.

vwestlife
May 2nd, 2010, 08:58 AM
i've got a cirrus logic that has both connectors.

I think that was just for convenience with the early Multisync monitors which only used a 9-pin connector, so you wouldn't need to use a 9-pin-to-15-pin adapter. The signal being output through the 9-pin port is still regular VGA, not a downconversion of VGA to CGA or EGA (unless it's an VGA/EGA combo board and you're running it in EGA mode).

JohnElliott
May 2nd, 2010, 01:46 PM
I am pretty sure that CGA and VGA cards cannot be installed simultaneously, because their bioses both require use of the same location in memory.

CGA cards don't have a BIOS. But if you do have both cards, the VGA one can only use mono modes, because in colour modes it uses the same I/O address space as the CGA.

mikey99
May 2nd, 2010, 03:57 PM
I think that was just for convenience with the early Multisync monitors which only used a 9-pin connector, so you wouldn't need to use a 9-pin-to-15-pin adapter. The signal being output through the 9-pin port is still regular VGA, not a downconversion of VGA to CGA or EGA (unless it's an VGA/EGA combo board and you're running it in EGA mode).

The "ATI VGA Wonder 16" is one 16 bit card that works in an 8 bit slot and has 9 and 15 pin connectors.
The card will drive a VGA display through the 15 pin and CGA/EGA/MDA displays through the 9 pin connector.

ibmapc
May 2nd, 2010, 04:23 PM
The "ATI VGA Wonder 16" is one 16 bit card that works in an 8 bit slot and has 9 and 15 pin connectors.
The card will drive a VGA display through the 15 pin and CGA/EGA/MDA displays through the 9 pin connector.

There must be a way to get a composite signal from the CGA portion of the "ATI VGA Wonder 16", right? I'm assuming here since the IBM CGA Card has the pins for the composite monitor on the card but I don't see that on the "ATI VGA Wonder ". Maybe something could be soldered to the appropriate places on the card or connector? Please chime in if you can help me. Remember, my objective is to upgrade the external monitor capabilities without losing the internal monitor.

Greg

vwestlife
May 2nd, 2010, 04:54 PM
The ATI Small Wonder card has the pin header for the 5155's internal monitor. Many other CGA cards do as well, even if they don't have the RCA jack for an external composite monitor.

With an aftermarket CGA card, you don't gain anything in resolution, but you do eliminate the "snow" that the original IBM CGA board is plagued with. Some (like the Small Wonder) also can eliminate the composite color burst, so that colors are rendered as pure grayscales (or "amber-scales") on the 5155's display, rather than as gritty patterns which can render the characters unreadable (typing MODE BW80 will fix this, but some programs ignore this setting).

ibmapc
May 2nd, 2010, 05:33 PM
What!? no SNOW?! But that's part of the personality of these old machines. For that reason onlly, I'll keep my old CGA card in a box, so that I can put it back in if I get nostalgic!!

Chuck(G)
May 2nd, 2010, 06:04 PM
That V& VEGA VGA that I have is similar to this one (http://stason.org/TULARC/pc/graphics-cards/U-Z/VIDEO-SEVEN-XVGA-V7-VEGA-VGA.html) but is an 8 bit card.

On its own, it can emulate a VGA, EGA, HGC or CGA. Co-resident with a CGA, it can emulate HGC or EGA. Regardless, the two output connectors are analog and digital--the digital can support MD, CGD, EGA or multisync EGA. The analog output can support VGA, SVGA, IBM 8503, 8512, 8513 or 8514.

I'm quoting from the manual.