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View Full Version : need help - Vermont Microsystems dual slot graphics card



Chris2005
March 7th, 2005, 05:34 PM
I obtained this thing a number of years ago. I did plug it in once or twice, did bring up a display (I imagine on my original Multisync II). I'm thinking this thing is sort of along the lines of an IBM Professional Graphics card, and may even have been a competitor back in those days. If anyone knows anything about the company, if they're still around, or prefererably has info on the card or perhaps (year right) drivers, I'd love to hear from you. The thing has an 80186 uP onboard. Those were the days...

rdwells
August 17th, 2006, 11:25 AM
I obtained this thing a number of years ago. [...] I'm thinking this thing is sort of along the lines of an IBM Professional Graphics card, and may even have been a competitor back in those days. If anyone knows anything about the company, if they're still around, or prefererably has info on the card or perhaps (year right) drivers, I'd love to hear from you. The thing has an 80186 uP onboard. Those were the days...

I hope it's okay to reply to a year-old post...

You're right about the VMI card being "along the lines of" the PGC; in fact, the PGC is the first version of the VMI card. VMI gave IBM exclusive rights for a year or so, and then VMI came out with their own (more powerful) version. (There's more to that story; let me know if you want to hear it.)

If you can program a PGC, you can program the VMI card. IIRC, there are 3 2-byte buffer pointers at C800:0000 (or maybe C400:0000), and the 256-byte circular buffers are at C800:0100, C800:0200, and C800:0300 (again, those segment addresses may be C400). One buffer is for input, one is for output, and the third is for error information.

Each buffer point pair consists of a read pointer and a write pointer. To send a command, you would get the write pointer, write a byte to that offset of the input buffer, and increment the write pointer (since it was a single byte, it would wrap at the end of the buffer).

One minor difference between the VMI and PGC boards, which I found out the hard way: The VMI board would allow you to read the read/write buffer pointers as a single 16-byte read. The PGC did not allow this. I actually impressed an IBM engineer when I explained how I figured this out....

Let me know if you still want more info, and I'll see what more I can dig out of these long-abandoned recesses of my memory.

- Rich

dreddnott
August 17th, 2006, 11:35 AM
In anycase, welcome to the forum!

Lucky for you Chris2005 still frequents these parts.

Chris2005
August 23rd, 2006, 01:26 PM
yes any relevant info would be welcome. I actually have a line on a PGA card, got the monitor already. Got to get those gears in motion...

dressler17
July 21st, 2010, 08:47 AM
I just found this 2005 post. If anyone is still interested, I was a design engineer at VMI and have internal information about the cards somewhere still on an old disk drive, as well as several of the earlier cards (a couple of product lines) themselves. It is true that we extended the original IBM card and some of the leading design engineers are prominent players in the graphics industry in other companies today. Contact me at david_ressler@yahoo.com for additional information if you are interested.