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IBM 3270 PC/G Video Card?

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willmurray461

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I recently acquired this vintage IBM card because its top card connector slots interested me. Usually, these are exclusive the IBM 3270 PC machines, and since I have a 3270 PC, I decided to test it. However, when I booted the machine up, it gave me a video card error. The diagnostics disk recognized it as an All Points Addressable board, but gave me a memory error when I attempted to test it. There are some differences between my older APA board and this one. This one has two card connectors as opposed to the one on my other APA card, and features two large chips. I read somewhere that the hardware in the IBM 3270 PC/G and PC/GX were incompatible with the plain old 3270 PC. Could this be a card from a 3270 PC/G or GX, or perhaps a 3270 PC AT? On the metal slot cover, there is the letter "g" printed on it. Also, does anyone here own or have pictures of a 3270 PC/G or PC/GX?IMG_0169.jpgIMG_0171.jpgIMG_0173.jpg

Hi-Res versions here: https://drive.google.com/drive/folders/1qtpSd3yT8nadQsoCyWRbbbbU5nBwBpmF?usp=sharing
 
I have the programmed symbols board for the AT variant of the 3270 pc. The installation manual for it describes two different possibilities depending on the presence of a card with a “g” printed on the plate; I think this is that card. IBM referred to it as the expanded graphics adapter. Information is scarce but John Elliott’s page on the 3270 pc indicates it would still use the 5151 or 5272 monitors suggesting this isn’t for the g or gx variants.
 
John Elliott's page only covers the 5271, neither the 5273 (PC/G/GX), nor the 5371/5373 (AT & AT/G/GX). I tried it with my fully functional 3270 PC (5271), but it would not work. I have both the 5272 and 5151. If your documentation suggests that a board with the "g" on it is the expanded graphics adapter, then I would assume that the card I own is a card for the 3270 PC G/GX, or AT/G/GX. By the way, what equipment do you have with your 3270 AT (e.g. unit #(5371 or 5373), monitor(5271, 5151, 5279, 5379), keyboard(AT or F122), cards)?
 
Near the bottom of the page there is a section for related PCs, mention of the graphics adapter is in the table there.
I only have the 5271, not the AT version. I picked up the PS board without realizing it wasn't the 5271 version. On a side note, as far as I can tell the only visible difference between mine and the normal one is that the card edge connector is shaped to fit in an AT. Also, since both the PS and "g" cards have two top connectors, this setup uses a three position top connector.
 
That's what I thought, unless there was some kind of PS card with only one top connector. Does your installation guide mention a three position connector?
 
AFAIK the PS and APA options were combined on one card for the 5273, and this is the board. The G and GX both use an external graphics processor; there is no display adapter in the system unit (unless you count the bus interface for the external box).
 
Interesting. That would explain why there were two top connectors on this card, given that there are only three on the display adapter and the PS takes up two. However, why would the PS for the AT mention this card, if installing it in a system with a "g" card would unnecessarily give you two PS's. Cfsimmons, is there any way you could scan the part mentioning the "g" card? Also, what would be the purpose of the top connectors if there was an external graphics unit, meaning no display adapter to plug into? What would they connect to? Also, where would the external graphics unit plug into?
 
There is no base 527x display adapter in the G or GX and consequently no top connectors for anything. The PS and APA are irrelevant. There is a bus adapter for the external unit, instead.
 
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Unfortunately I won't have access to the board or the documentation for a couple weeks. When I do, I will post them for the sake of documenting these strange card.
My current understanding is that PS board I have can be installed either with or without the G card, and thats why the installation instructions mention it. If the whole sweet of cards is installed a three position connector is used to share one of the three connectors on the main board. There is also a long two position connector for the PS board that goes over the G board for the PS's other connector.

You can also refer to pages 52 and 53 here...
http://bitsavers.org/pdf/ibm/pc/PS2_and_IBM_PC_Product_Reference_Version_4.0_Apr87.pdf
 
"AFAIK the PS and APA options were combined on one card for the 5273, and this is the board."
"There is no base 527x display adapter in the G or GX and consequently no top connectors for anything."
I'm a bit confused. You said this card is for the 5273 (G/GX), however it does have top connectors. So is it not for the 5273, or does it connect to something else?
 
willmurray461 said:
"AFAIK the PS and APA options were combined on one card for the 5273, and this is the board."
"There is no base 527x display adapter in the G or GX and consequently no top connectors for anything."
I'm a bit confused. You said this card is for the 5273 (G/GX), however it does have top connectors. So is it not for the 5273, or does it connect to something else?
Click to expand...

5273 == AT 3270. G and GX are options. Wikipedia indicates G/GX are 537x, but IBM marketing suggests the 537x are 5250 based. I've never seen the G, the GX, the 5371, or the 5373, so I can't comment on that.
 
Oops, mixed up 5273 and 5371. I understand now. I'm still curious about the reason why this card would be installed alongside a PS, if it had the same functionality. Maybe someone would need 16 additional font sets? The document that cfsimmons posted does confirm that the G/GX versions were referred to as 537x. It also mentions a "display attachment unit," which is probably the external graphics unit you talked about.
 
willmurray461 said:
I'm still curious about the reason why this card would be installed alongside a PS, if it had the same functionality.
Click to expand...

I will have to see if I can find the source of my suspicion that the so-marked "G" board combines PS and APA functionality on a single board. In that case, you wouldn't install it alongside a PS, you'd install it instead of one.

Pretty sure though it's something different than the 3270/G.
 
So I just bought this information booklet about the 3270 PC and it's got some really interesting information about the 3270 PC series/ Unfortunately it's in German, so I'm going to have to google translate everything. However, from what I can tell from the pictures, the PC 3270/G does not have an external graphics unit, however the 3270 PC/GX does. This card could still theoretically be from a 3270 PC/G. However, I would still like to see the documentation about the PS/APA combo card. The brochure also has some interesting information about special graphics tablets, optical mice, and special plotters.IMG_0326.jpgIMG_0327.jpg
 
You mean to say it's integrated into the monitor? The booklet has another picture of just the monitor and it does not seem detachable. The booklet shows each of the monitors 5272, 5279, 5279 on their own, and the 5279 (the one that came with the 3270-PC/G) has that grill on the bottom. Maybe it was for ventilation or just aesthetics. I'll have to translate more of the brochure to find out. Anyway, the booklet seems to describe how the enhanced graphics offered on the G/GX models is the feature of "Vector to Raster" conversion. I don't know what this means, but apparently that's what the graphics units were used for.
 
Yeah, I was wrong again. That thing on the bottom of the monitor seems to be another display unit. It also looks like this might be an Extended Graphics Adapter. Those are only for the 3270-PC and 3270-AT, which would make sense.
 
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