[Info-vax] VMS port to x86

[Johnny Billquist]

On 2012-03-21 20.32, Bob Koehler wrote:
> In article<jkcjcn$p3r$3 at Iltempo.Update.UU.SE>, Johnny Billquist<bqt at softjar.se>  writes:
>>
>> No, they don't.
>
>     Intel, not to mention every other reference I've seen, says they do:
>
> http://www.intel.com/Assets/en_US/PDF/manual/253668.pdf?wapkw=cpu+architecture+mode+ring
>
>     Intel. 64 and IA-32 Architectures
>     Software Developer.s Manual
>     Volume 3A:
>     System Programming Guide, Part 1
>
>     "The processor.s segment-protection mechanism recognizes 4 privilege
>      levels, numbered from 0 to 3."

My bad. Anyway, you do not need four hardware levels in order p[ 
implement VMS. Two is what really is needed. The rest can be solved in 
software, although having hardware makes it easier/more efficient.

	Johnny