On 05/27/2017 09:15 PM, Josh Dersch via cctalk wrote: > So I had a random thought in the wee hours this morning and I leave it > to you, the cctalk braintrust, to tell me exactly how stupid this idea > is: > > I have a VAX-11/750, an Able QNiverter (UNIBUS->Qbus adapter), a > 22-bit Qbus backplane, and a VCB02 (QDSS) 4-bit graphics boardset. > > Theory: With an appropriately modified NetBSD driver for the VCB02, > such that it provides only 18-bit addresses to the VCB02's DMA engine, > I can get X running on the VCB02 on the 11/750. > > That is, the configuration is: 11/750->Unibus->QNiverter->Qbus->VCB02. >
Should work with one thing I can think of the VCB02 is Q22 not Q18. Its 22bit. The VAX hardware is for memory 32bit and for IO only 16bit. ( A 16 bit segment mapped to IO.) The bit map is mapped as Q22 memory. > Obviously the console functionality of the VCB02 won't work since that > requires support on the VAX side of things that won't be present, but > I think everything else should work. I've browsed the technical > manual and I don't see anything that should get in the way, I'll just > need to hack up the driver appropriately. > It works in a Qbus microVAX! However starting up you will need a terminal until it all works. Part of getting it all working is a NETBSD build for the odd concoction. > But this is something that randomly popped into my head (I was > inspired by a research paper, "A VAX Based Data Acquisition Computer > System at the Nuclear Structure Research Laboratory" wherein a Matrox > QRGB Qbus graphics board was lashed to an 11/750 in a similar manner... > > What say you all? > > - Josh >