[Simh] More VAX Simulators

[Johnny Billquist]

On 2019-04-21 16:13, Timothy Stark wrote:
> Wow!  I try that new simh emulator soon.

Definitely sounds interesting, yes...

> Have you try implementing VAX 3100 M96/M98, VAX 4000 M106/M108, and VAX 
> 4000 M90 yet?
> 
> How about VAX 66x0 that provides full 32-bit addressing for up to 3.5 GB 
> main memory?

You know that technically, it supports 34-bit physical addresses, right? 
However, I'm not sure DEC ever built any VAX model capable of using it, 
nor do I know if VMS supports it.

Virtual address space would still be 32 bits, of course.
And as far as I know, only NVAX supported the 34-bit physical address 
space, and it does require changing some registers before the MMU page 
address registers go to 25 bits. But it might be that you also need to 
go to that mode in order to use 3.5G of physical memory. I can't 
remember for sure...

The 66x0 machine I'm pretty sure didn't allow for more than 32-bit 
physical addresses. But I'm wondering about the 7000 models...
Not sure if you could even go to 3.5G on the 66x0 machines. The CPU can 
do it, but I wonder about the bus structure.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol