Every MINC system came with a GPIB – IEEE488 interface, and it is described in a dedicated volume in the MINC manual set – book 5. So, obviously, the PDP2011 MINC has to have GPIB too.
And if that wasn’t reason enough, the XXDP disk packs have chains of tests specific to the MINC that include testing the GPIB hardware, and it’d be too cool to be able to run those without error messages, hangs, or changes. So I’ve added another MINC module called ibv11.vhd that implements the logic for the GPIB interface.
It passes the VIBB MAINDEC test – that was the whole point of adding it. But it doesn’t have the external signals that a ‘real’ GPIB interface would have yet, and I don’t know if it would actually work with real GPIB hardware. And there’s a very simple reason for that: I don’t own or have access to any hardware that has GPIB interfaces, and everything I’ve found so far is prohibitively expensive, not guaranteed to work properly, or so obsolete it’d require a significant project to restore it – and mostly all of that at the same time.
What I’d need is a working setup of a master (something like a pc card and some software, probably, but it could be anything really) and an instrument – so as to have something to compare to as well as something to test against. And cables to connect the various items – the reason I’m mentioning that is that I’ve seen those listed for hundreds of dollars too.
That’s where it is – the logic is there, it passes the test, and it is probably near 80% of what a real implementation would need. And the only purpose it serves now is that it allows running the original test chains. But only if you configure it to be included – like everything in PDP2011, if you don’t configure it, it won’t be included, won’t take any resources, or even be observable in the compiled system. A stub, if you will, ready to be expanded if and when I might find the hardware I’d need.