Looking for info on *REALLY* old graphics card...

[laserhawk64]

NOTE 1: This is a (more or less) cross-post from here:
http://www.old-computers.com/f...rum_posts.asp?TID=5413
I wasn't getting any replies there, so I thought I'd try somewhere else.

NOTE 2: I will be cross-posting on HardForum if and when I resolve a small email issue with them... just trying to get all the info I can...

NOTE 3: This is a LONG post. I apologize for that. I'm trying to give all the info I have, so that you folks can tell me what I'm holding.

--------

That said... I have an ancient (and I do mean *ancient* ISA-8 graphics card. It's stamped with "1501483 XM" and all Google will tell me is that it's made by IBM and that it is, in fact, some sort of primitive attempt at making a computer display information on something other than a TV or front-panel blinkies.

Pictures of the card are here:
Hi-Res (200 dpi) -
http://img444.imageshack.us/im...1483xmvidcardhires.jpg
Lo-Res (72 dpi) -
http://img21.imageshack.us/img...1483xmvidcardlores.jpg

I don't have any idea if the card works; and with neither a compatible monitor nor an oscilloscope, I have no way of testing it. I don't have a suitable PC-side interface, either. All I've got is in the pics -- the card itself.

What I know (and what I suspect) is as follows:

The card has a Motorola 68xx MPU and almost all of the other chips are 74xx / 74xxx TTL discrete logic ICs (e.g. 7408 quad 2-input AND gate); there appear to also be several chips numbered 2114 (I seem to recall from *somewhere* that these are RAM chips, but I'm not entirely sure). *ALL* of the chips are in the classic '80s DIP package, except the clock chip.

The clock chip reads to be a 16.257MHz crystal oscillator. I believe that it is a quartz clock chip and *not* a "crystal resonator"... but I don't know.

There is a socketed chip next to the MPU; all I can tell from the chip is that it is made by AMD.

There are two connectors on the bracket. Neither one has a label. One is a DB25F (think "Parallel" / LPT port) and the other is a DB9F (think COM port). My best guess is that the DB9F is the video out.

There are several (significantly less prominent) markings elsewhere on the card. They are:
- Near the ISA-8 connector, it says "BLACK & WHITE/PARALLEL".
- Near that marking, and next to a capacitor labeled C1, the number "706" has been stamped on.
- On the reverse side of the board (not in pics) there are two labels under the port connections. One says "1501450", and the other says "MC2VO 339".

Also, there is a strikingly similar card pictured on this Wikipedia page. That card appears to be identical in terms of chip placement, but it has a different model number.

What I want to know is as follows:

- What kind of card is this? Is it, in fact, a graphics/display card of some sort, or is Google telling me wrong?
- What does it do? What protocol does it use, and how, exactly, does it go about its business?
- Where did this card likely come from? (I no longer recall exactly how I acquired the card...) What sort of system would even *use* this thing?
- How rare is this card? Is it common? Uncommon? "Hens' Teeth" rare?

Please help me with this, I'm very interested, and I can't find a thing that is for certain (other than what I've said so far). I'll be glad to take more pics if anyone needs them, and I can supply a list of chip numbers and quantities if I absolutely have to. I don't recognize all of them, but maybe someone else will....

Thanks, folks! (...and sorry that the post is this long...)

 

[Sahakiel]

From the Wikipedia link:
http://www.seasip.info/VintagePC/mda.html

Quick glance, it seems the CRT controller has the same model number: MC6845SP
As I recall, outsourcing external logic chips to whomever had the lowest bid wasn't uncommon. Suppliers didn't always have contracts or capability to support mass manufacturing, so the chips on cards would vary.
The AMD chip looks to be the character ROM. If I remember correctly, AMD started life manufacturing memory in competition with Intel.
Pinouts for both ports are through the link. DB9 is video, DB25 is printer. The "BLACK & WHITE/PARALLEL" label is probably a reference.

 

[laserhawk64]

Useful info! I had already found that link... however, it does not *confirm* this card directly as an MDA. In lawyerspeak (my mother is an attorney, not me), it's "circumstantial evidence". It points, in this case, further towards the possibility of this card being an MDA. It does not, however, say explicitly anywhere that the card *is* (like, for totally sure) an MDA.

Note that in my original post, I said this:

Also, there is a strikingly similar card pictured on this Wikipedia page. That card appears to be identical in terms of chip placement, but it has a different model number.

Since the two have similar chip placement, but are different models (probably even different manufacturers), I can only say that my card *might* be the same type. Is it likely? Yes. Is it *highly* likely? Yes. Can I be completely, 100% certain? No.

Not trying to argue, just saying that I'm still not sure what I've got.

 

[OVerLoRDI]

Out of pure curiosity, and sorry I am no help to you in your quest of figuring out what this card is, but was it common back in the day to have printer ports on video cards?

Edit: Actually wait, that makes a huge amount of sense. The video card would basically just dump its buffer to the print and it would print a screen shot, seems like it would fit given the GUIs (or well lack there of) of the time.

 

[nitromullet]

Perhaps a vendor for the Motorola MC6845P chip may have more information or access to spec sheets for the chip.

http://octopart.com/info/Motorola/MC6845P

If you want anyone online to be able to tell you more about the any of the other chips, you are probably going to have to take a better picture. Most of the chip markings are illegible in your photo.

 

[zephyrprime]

There weren't that many different types are cards running around back then. There cga (which I had and this isn't since it has two ports), and later hercules (which also only had one port). Since the layout is so similar to the mda picture you found, it's almost certainly mda.

 

[Sahakiel]

Originally posted by: laserhawk64
Useful info! I had already found that link... however, it does not *confirm* this card directly as an MDA. In lawyerspeak (my mother is an attorney, not me), it's "circumstantial evidence". It points, in this case, further towards the possibility of this card being an MDA. It does not, however, say explicitly anywhere that the card *is* (like, for totally sure) an MDA.

Note that in my original post, I said this:

Also, there is a strikingly similar card pictured on this Wikipedia page. That card appears to be identical in terms of chip placement, but it has a different model number.

Since the two have similar chip placement, but are different models (probably even different manufacturers), I can only say that my card *might* be the same type. Is it likely? Yes. Is it *highly* likely? Yes. Can I be completely, 100% certain? No.

Not trying to argue, just saying that I'm still not sure what I've got.

100% certain just doesn't exist except under constrained conditions, especially in regards to electronics. I'm almost willing to bet you believe the sun will rise tomorrow with 100% certainty.
Since you seem rather fond of taking an idea and running it out of bounds, I suggest you look into the engineering concept of black boxes. In short, all that matters is what goes in and what comes out. What's actually inside doesn't enter the equation at all.
That explains why you will never be 100% sure short of breaking out the microscope and scanning every single die inside every single chip on that pcb and comparing them to their corresponding masks; assuming IBM still has them. Technically, equal functionality can be emulated through different means so even if you had a compatible system to test the card, the software is still suspect.
Aside from a couple edge cases, your mystery card is a MDA/printer combination. You're welcome to keep pursuing your endeavor, though. As far as I'm concerned, you already have your answer.

 

[deimos3428]

Originally posted by: OVerLoRDI
Out of pure curiosity, and sorry I am no help to you in your quest of figuring out what this card is, but was it common back in the day to have printer ports on video cards?

Yes. Various types of "I/O" were placed on the same card, and video wasn't considered particularly special then (because it wasn't).

 

[deimos3428]

These were used in the IBM PC Model 5150, which were fairly popular at the time. By now their rarity has surely increased, but their value would be minimal except to a collector or enthusiast in search of one.

 

[VirtualLarry]

I've got a bin full of mono/parallel 8-bit ISA cards, if anyone needs one.

That being said, they're not really worth much of anything, not even for scrap.

 

[nitromullet]

Originally posted by: deimos3428
These were used in the IBM PC Model 5150, which were fairly popular at the time. By now their rarity has surely increased, but their value would be minimal except to a collector or enthusiast in search of one.

Looks like $30 would get you one. http://cgi.ebay.com/IBM-PC-515...44132526QQcmdZViewItem