[Info-vax] HP adds OpenVMS Mature Product Support beyond the end of Standard Support

[Johnny Billquist]

On 2014-02-02 10:24, Bill Gunshannon wrote:
> In article <lcl27t$8nd$2 at iltempo.update.uu.se>,
> 	Johnny Billquist <bqt at softjar.se> writes:
>> Eh.. What? Any "modern" PDP-11 already have 22 address lines...
>> My PDP-11 at home have 4 megs of ram.
>> Have you never seen a PDP-11 with that? Under which rock have you been
>> the last 40 years, Bill? :-)
>
> Of course I have.  I have an 11/93.  Only has 2meg and I have never been
> able to find any PMI for it.  But I want more!!  My comment on the 6809
> was only to show that 16 address lines didn't limit it to 64K so why
> should 22bist limit the PDP-11 to a measly 4meg.  :-)

You cannot use PMI memory on the 11/93. But you can just solder in the 
missing chips to get to 4 Meg. I've done that on several boards.

As for getting more than 64K for a program on a PDP-11 in a way 
comparable to the 6809, that is truly what overlays do, in a very 
similar way. Or atleast it can under RSX. I'm not so sure with Ultrix...

In RSX, overlays can be of two sorts. You can either have disk resident 
overlays, in which the "right" code gets read in to your 64K address 
space as needed, and the other parts get written over, or you can have 
memory resident overlays, in which the MMU remaps your 64K address space 
to the right pieces of code, as needed.

If you need more that 64K of data, you can do that to. That is what the 
PLAS system calls are for. You just grab a large chunk of memory, and 
then request the MMU to map to whatever section of that memory space you 
want to play with.

> I guess it's really is true.  This is not the medium for subtle humor.

When it comes to PDP-11s, I take almost everything serious. :-)

	Johnny