How to connect an external montor to IBM 5155 portable?

[Jason.]

This IBM 5155 has 640k memory and a standerd CGA card. I saw "It could however, display color if connected to an external monitor " when I google "IBM 5155 protable ". Is there some jumpers should be changed when I plug in a external monitor ? Will this fry the card or something? Any Help will be appreciated.

[southbird]

It's just a standard IBM CGA card (unless it was replaced or something.) Just plug in a CGA-compatible monitor to the DB-9 port.

[IBMMuseum]

Originally Posted by southbird

It's just a standard IBM CGA card (unless it was replaced or something.) Just plug in a CGA-compatible monitor to the DB-9 port.

Agreed, I was just reviewing the PPC GTO last night that OJ traded me...

You don't have to change motherboard switches or connections from the internal screen...

On the same bracket that has the RCA plug (which is composite video, something to try to something like a TV)...

[Jason.]

What happend to the internal monitor when I plug in the external one? Will it still keep working? I just want to make sure nothing unexpected happend, because a friend of mine told me this
"Note that you need to plug in the jumper wire from the internal monitor. If I was to plug in an external monitor, it'd be color. Make sure the jumpers on the motherboard are set to the correct monitor or you will surely fry the card."
So I am confused now Does anyone have done this before ?

[Jason.]

the build in monitor
it's cool

[mikey99]

Originally Posted by Jason.

the build in monitor
it's cool

Yes, I agree with that I found a 5155 locally on craigslist for free
awhile back. I added a Seagate 225 hard drive. The guy I got it from
even kept my number and called me a few months later when he found
all the manuals and a bunch of software for it.

I've never tried attaching an external monitor though. Since the built
in monitor is actually composite CGA, I think the motherboard switches
should be set for CGA card with a color monitor. They probably already
are set that way but its a good idea to check.

[southbird]

In any case, you won't "fry the card" as long as you're hooking up a compatible monitor. At worst you'll have wrong or no output. But yes, AFAIK, the 5155 is set as a color CGA; the built-in monitor is just a composite screen without color (though it does support "shades" of amber, and I have hooked both standard NTSC TV output and converted VGA output through it before.) So the data is already in "color." After all, the point is that you just "plug n' play" an external monitor for full color.

[Fallo]

Originally Posted by southbird

In any case, you won't "fry the card" as long as you're hooking up a compatible monitor. At worst you'll have wrong or no output. But yes, AFAIK, the 5155 is set as a color CGA; the built-in monitor is just a composite screen without color (though it does support "shades" of amber, and I have hooked both standard NTSC TV output and converted VGA output through it before.) So the data is already in "color." After all, the point is that you just "plug n' play" an external monitor for full color.

Of course, you do have the problem that color appears as ugly vertical striping due to the internal monitor's inability to utilize the chroma signal. You can see a similar effect when using a color composite monitor. Faint vertical bars appear on the screen because of chroma being interpreted as luminance. Ordinarily this would produce dot crawl, but on CGA the phase shift stays constant from line to line, hence you get bars rather than a checkerboard pattern.

[IBMMuseum]

Ok, I just found a thread from almost a year ago, where connecting the internal screen to an ATI EGA Wonder was discussed. The OP (whom has still posted here within a few days ago) never said whether he was able to get it working however. As I have both components here, I might give it a try soon.

I don´t know which version of the card I have, one that apparently uses some kind of daughtercard attaching by the 8-bit I/O bus, and a header to use the onboard LPT port...

[MikeS]

Originally Posted by IBMMuseum

Ok, I just found a thread from almost a year ago, where connecting the internal screen to an ATI EGA Wonder was discussed. The OP (whom has still posted here within a few days ago) never said whether he was able to get it working however. As I have both components here, I might give it a try soon.

I don´t know which version of the card I have, one that apparently uses some kind of daughtercard attaching by the 8-bit I/O bus, and a header to use the onboard LPT port...

You're not thinking of the Graphics Solution card? I have several of those and one does have the I/O port daughterboard, but I've not seen an EGA Wonder like that; mine don't, but of course that doesn't mean they didn't exist.

FWIW, the manuals are pretty clear that they both work in a PC Portable, and they also support certain combinations of dual (different mode) displays as long as they don't use the same video memory.