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Re: Larger memory option for VAXstations

On 2015-08-19 16:01, emanuel stiebler wrote:
On 2015-08-19 04:50, Johnny Billquist wrote:
On 2015-08-18 22:06, John Klos wrote:
Faster SCSI wouldn't be so bad, too :)

But you like to keep all your old drives too, right?
So not knowing, what nemonix really did, they probably just plugged in a
second SCSI controller into the system with something like 53c875,
and wrote additional drivers to access it ...

Hmm. I don't think Nemonix required any changes to the system, so I would be surprised by a new driver. That said, it might just work like the standard SCSI controller, so the standard driver would work. And wide/fast SCSI can still deal with old/slow drives on the bus, so I don't think you actually need a second controller. That could be the only one and you could be happy. But I'm just making guesses.

But from a CPU point of view, there is nothing speical about
going to 512 Megs. Or even more. But if you go for more physical memory,
you need an NVAX (which I think the 4000 machines have), and the OS
needs to change the mode of the CPU, which I suspect VMS will not do on
a 4000 machine, as they would not expect you to have that amount of
physical memory that would require changing from the default mode.

The firmware tells the OS, how much memory you have, right?

Yes, through VMB. And VMB probes the available memory. So just having memory expanded do not need a different firmware. VMB should already handle things. The possible issue would be if VMB on the 4000 always stops at (say) 128M, since it would "know" that there can't be any more.

Of course, we could do that in NetBSD, but I don't think we support a
single NVAX type machine yet...

4000/90 and up are supported, aren't they?

Yikes. My mistake. I even have NetBSD installed on my 4000/90. :-)


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