[Info-vax] [OT] Portable operating systems, was: Re: PowerX Roadmap -

[Scott Dorsey]

In article <nrsf1n$ft1$2 at dont-email.me>, GreyCloud  <mist at cumulus.com> wrote:
>On 09/20/16 14:18, Scott Dorsey wrote:
>> In article<nrrrl7$84n$1 at dont-email.me>, GreyCloud<mist at cumulus.com>  wrote:
>>>
>>> Not totally true on the modes.  Why did Data Generals machines have 8 modes?
>>> I know they went out of business, but why 8?
>>
>> Because if you want five modes, you might as well just make eight because
>> it takes the same number of bits in your opcode.
>
>Now that sounds like more of a plausible answer.

That is, in fact, the answer.  However, it brings up the question of why you
would want five rather than four.  (If your kernel can trust your drivers then
you really only need two, but who can trust drivers?)
--scott
-- 
"C'est un Nagra. C'est suisse, et tres, tres precis."