Re: rtVAX300 .. need help..

[christos%astron.com@localhost (Christos Zoulas)]

In article <759FA549-4B6A-49AA-B9DD-5C1CAC4F5D46%comcast.net@localhost>,
Paul Koning  <paulkoning%comcast.net@localhost> wrote:
>
>On Jan 10, 2013, at 4:33 PM, Rhialto wrote:
>
>> On Thu 10 Jan 2013 at 04:29:36 +0100, Johnny Billquist wrote:
>>> Just a few short comments. The VAX internal registers are not memory
>>> mapped, ever. That would be against the architecture specification.
>> 
>> Well, the thought isn't that strange. Iirc, the PDP-11 has its CPU
>> registers mapped (somewhere in high memory?) and the PDP-10 too (at
>> address 0, iirc).
>
>PDP-11 CPU internal registers appear in I/O address space, with some
>exceptions: the general registers are not visible there except in the
>11/10.  (They have listed addresses, but those only work from the
>console, not from programs, with that one exception.)  And yes, on the
>PDP-10, the general registers live at memory addresses 0 to 017.  

This is why we should modify c to allow:

        register int i;
        int *x = &i;

christos