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per
September 30th, 2009, 01:49 PM
If I was offered an non-tested IBM Professional Graphics Controller for $80, should I take it?

I have no idea if it works or not, but figuring therse are getting hard to find... Is it worth $80?

I know it is pretty easy to make a PGA-VGA cable, but actually how do I do this?

IBMMuseum
September 30th, 2009, 01:52 PM
...I know it is pretty easy to make a PGA-VGA cable, but actually how do I do this?

That would be my question too, as I have the boards, but not the monitor...

per
September 30th, 2009, 02:01 PM
That would be my question too, as I have the boards, but not the monitor...

I think Trixter was the one that wrote about such an adapter once, stating something about the "crispiest colors you'll ever see on a VGA monitor". I may be wrong, but I have certanly read about an adapter.

BTW, how much did you pay for yours, or did it just accidentally fall into your hands?

per
September 30th, 2009, 02:32 PM
From the IBM PC PGC Tech Ref, p/n 6138661, 8/15/84:

1 Red
2 Green
3 Blue
4 Horizontal and Vertical Sync
5 Mode Control (400-line / 480-line)
6 Ground for Pin 1
7 Ground for Pin 2
8 Ground for Pin 3
9 Ground for Pins 4 and 5


Seems like it is using a composite sync signal. But why doesn't it combine the video outputs into one composite output?

Chuck(G)
September 30th, 2009, 02:54 PM
Seems like it is using a composite sync signal. But why doesn't it combine the video outputs into one composite output?

Quality. Composite (CVBS) video is really a low-quality method of transmitting video. It has plenty of quirks and issues. It would be pointless to do it on something like PGA; you'd be back in CGA territory if you did. On the other hand, combining sync is a good idea--the H and V signals are essentially digital and do not interfere with each other.

A bit on the why's and wherefore's of composite video decoding (http://www.intersil.com/data/an/an9644.pdf)

per
September 30th, 2009, 03:02 PM
Quality. Composite (CVBS) video is really a low-quality method of transmitting video. It has plenty of quirks and issues. It would be pointless to do it on something like PGA; you'd be back in CGA territory if you did. On the other hand, combining sync is a good idea--the H and V signals are essentially digital and do not interfere with each other.

A bit on the why's and wherefore's of composite video decoding (http://www.intersil.com/data/an/an9644.pdf)

But does it use standard RGB on the video data pins then? and if so, is it possible to drive a VGA monitor just with the composite sync signal (connected to hsync of the VGA monitor) and the video data signals?

Anyways, is it still worth $80 even if I buildt an adapter?

southbird
September 30th, 2009, 03:29 PM
But does it use standard RGB on the video data pins then? and if so, is it possible to drive a VGA monitor just with the composite sync signal (connected to hsync of the VGA monitor) and the video data signals?

My GUESS answer would be MAYBE. It seems different monitor makes and models can do different things. But failing that, this page (http://www.epanorama.net/documents/vga2rgb/scart.html) talks about sync separation and includes a demo circuit (that I'm probably going to build and try out in the near future) that supposedly can split the signals. I don't know if it's necessary in your case, but it's interesting...

IBMMuseum
September 30th, 2009, 04:59 PM
...BTW, how much did you pay for yours, or did it just accidentally fall into your hands?

I acquired it years ago, probably not just by itself...

Chuck(G)
September 30th, 2009, 05:09 PM
My GUESS answer would be MAYBE. It seems different monitor makes and models can do different things. But failing that, this page (http://www.epanorama.net/documents/vga2rgb/scart.html) talks about sync separation and includes a demo circuit (that I'm probably going to build and try out in the near future) that supposedly can split the signals. I don't know if it's necessary in your case, but it's interesting...

The NEC LCD I'm sitting in front of can accept separate sync, combined sync and sync-on-green. But then, the VGA cable is connected to 5 BNC connectors...

Most high-end VGA monitors can accept a variety of sync configurations.

Chuckster_in_Jax
September 30th, 2009, 08:22 PM
If I was offered an non-tested IBM Professional Graphics Controller for $80, should I take it?

I have no idea if it works or not, but figuring therse are getting hard to find... Is it worth $80?

I know it is pretty easy to make a PGA-VGA cable, but actually how do I do this?

I don't think so. Prices are really low right now for eBay items. You might take the $80.00 and buy a really nice computer that is complete and in working condition.

Unknown_K
September 30th, 2009, 08:58 PM
Your best bet is to get a tested PGA video card and the monitor it was meant to work with (unless you just want the card as a checklist item to sit on the shelf and collect dust).

The cards are rare and I asume the monitors are more rare.

lutiana
September 30th, 2009, 09:10 PM
Hmm, this seems to delve into the A/V arena of things.

RGBHV is what that PGA seems to output, almost all VGA monitors will accept this and be ok with it.

So the question is what type of connector(s) are found on the back of the card? If they are BNC as I suspect them making and adapter cable is VERY easy, in fact you can buy them from any pro A/V dealer. Here (http://www.extron.com/product/product.aspx?id=syvgamalefibncmaleca&subtype=58&s=4) are some pre-made ones.

*Edit* its not BNC outs, its a DE-9 connector, so some soldering would need to be done.

per
October 1st, 2009, 12:16 AM
RGBHV is what that PGA seems to output, almost all VGA monitors will accept this and be ok with it.

No, RGBHV is what VGA uses. the PGC uses RGBS (composite sync).

At least, it is a standard, mening there is hope. All we have to do now is to find what monitors support RGBS.

lutiana
October 1st, 2009, 08:27 AM
At least, it is a standard, mening there is hope. All we have to do now is to find what monitors support RGBS.

Well most VGA monitors should run fine with RsGsBs (sync data is encoded with the color data) or RGsB (sync data is on the green wire) and even RGBS.

Your different video signals (in order of quality) are:
RGBHV -> RGBS -> RGsB or RsGsBs -> Component (C and Y) -> S-Video -> Composite. Almost all recorded video starts out as RGBHV and is downscaled from there.

So you would need to wire it up like this:
PCG to VGA
1 to 1 (R)
2 to 2 (G)
3 to 3 (B)
4 to 13 (Composite Sync data)
5 N/C
6 to 6 (R return or ground)
7 to 7 (G return or ground)
8 to 8 (B return or ground)
9 to 5 (Composite Sync data ground)

per
October 1st, 2009, 08:54 AM
Well most VGA monitors should run fine with RsGsBs (sync data is encoded with the color data) or RGsB (sync data is on the green wire) and even RGBS.

Your different video signals (in order of quality) are:
RGBHV -> RGBS -> RGsB or RsGsBs -> Component (C and Y) -> S-Video -> Composite. Almost all recorded video starts out as RGBHV and is downscaled from there.

So you would need to wire it up like this:
PCG to VGA
1 to 1 (R)
2 to 2 (G)
3 to 3 (B)
4 to 13 (Composite Sync data)
5 N/C
6 to 6 (R return or ground)
7 to 7 (G return or ground)
8 to 8 (B return or ground)
9 to 5 (Composite Sync data ground)

BTW, the school's throwing out stuff again, and I piced up a cable with a male 9-pin D-shell connector on one side and a normal male VGA connector on the other. Maybe that will work, at least, the only difference is that pin 5 of the PGA plug will be connected to pin 14 of the VGA monitor.

per
October 5th, 2009, 10:24 AM
Update
Made an offer and got the card for $45. I also bougth an IBM Analog input card (AKA.: Game-controller/Joystic adapter) along with it for $15 extra.

When I get it, it will be interesting to see if it actually works.

Chuck(G)
October 5th, 2009, 11:11 AM
Your best bet is to get a tested PGA video card and the monitor it was meant to work with (unless you just want the card as a checklist item to sit on the shelf and collect dust).

The cards are rare and I asume the monitors are more rare.

...and while the card has CGA emulation, software to use the PGA is even rarer, in my experience. The product window was too short--it wasn't that long before EGA and VGA arrived on the scene.

per
October 5th, 2009, 11:46 AM
...and while the card has CGA emulation, software to use the PGA is even rarer, in my experience. The product window was too short--it wasn't that long before EGA and VGA arrived on the scene.

What's less fun than writing your own software! If only I get it to work with a monitor first...